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NATURAL HISTORY, GENERAL AND PARTICULAR, BY THE COUNT DE BUFFON, TRANSLATED INTO ENGLISH.
ILLUSTRATED WITH ABOVE 260 COPPER-PLATES, AND OCCASIONAL NOTES AND OBSERVATIONS BY THE TRANSLATOR.
VOLUME I.
EDINBURGH: Printed for WILLIAM CREECH. M,DCC,LXXX.
YOU did me honour by permitting me to ad⯑dreſs to you my Tranſlation of your illu⯑ſtrious work; and I am now proud to exerciſe the privilege you ſo politely conferred upon me. The important Information it contains, and the Eloquence of its Compoſition, joined to the Ingenuity, Taſte, and Erudition with which it every where abounds, [ii] induced me to think that a Verſion of it into the Engliſh language, by diffuſing the knowledge of Nature, would increaſe the number of her ad⯑mirers. The taſk, it muſt be acknowledged, was arduous; but your approbation and encourage⯑ment, by redoubling my vigour, diminiſhed the difficulty of the labour.
It was with the livelieſt pleaſure that I re⯑ceived your Communications reſpecting the valu⯑able Performances you have already publiſhed, and concerning thoſe undertakings which now engage your attention and cares. I failed not to announce to your friends in this country the ad⯑vantages which Science and Literature have yet to expect from you; and I need hardly obſerve, that their wiſhes and my own, for the accom⯑pliſhment of your purpoſes, are in proportion to the greatneſs of your talents.
The ſucceſs which the Tranſlation met with, when publiſhed ſeparately in volumes, I imputed [iii] to the celebrity of your name, and to the high value of the original; and theſe cauſes, I truſt, will juſtify my anxious attention in laying it be⯑fore the Public in its collected and more perfect form.
NATURAL HISTORY is the moſt extenſive, and perhaps the moſt inſtructive and en⯑tertaining of all the ſciences. It is the chief fource from which human knowledge is deri⯑ved. To recommend the ſtudy of it from mo⯑tives of utility, were to affront the underſtand⯑ing of the reader. Its importance, accordingly, in the arts of life, and in ſtoring the mind with juſt ideas of external objects, as well as of their relations to the human race, was early percei⯑ved by all nations in their progreſs from rudeneſs to refinement.
But, notwithſtanding the great advantages a⯑riſing from the knowledge of Nature, Ariſtotle is the only antient writer on ZOOLOGY who me⯑rits attention. Inſtead of retailing fictions, or facts founded upon ignorance and credulity, he inveſtigated the relations and diſcrepances which connect and diſtinguiſh the various tribes of a⯑nimals. [vi] What had been only a chaos of de⯑tached, uncertain, and often fabulous narrations and deſcriptions, he reduced into a ſcientific form, with a ſucceſs ſo amazing, that, to this hour, no ſyſtematic view of animated beings has been attempted, the principles of which have not been adopted from Ariſtotle's hiſtory of ani⯑mals. His analogies and diſtinctions are taken not only from the inſtruments of motion, the teeth, the eyes, the heart, or other external and internal organs of the body, to which the atten⯑tion of our modern methodiſts has been chiefly confined, but from magnitude, figure, manners, faculties and diſpoſitions of mind. He attempt⯑ed not to arrange and define every known ſpe⯑cies. This labour he left to men of leſs geni⯑us and more patience. His work conſiſts entire⯑ly of philoſophical diſſertations on the gene⯑ral ſtructure, manners, and diſpoſitions of ani⯑mals; and his particular facts are always employ⯑ed to ſupport the principles which he is endea⯑vouring to eſtabliſh.
Pliny and Aelian, though they had the illu⯑ſtrious example of Ariſtotle before them, produ⯑ced nothing but crude collections, without diſ⯑covering much taſte, judgment, or knowledge of the ſubject.
From this period, till the voluminous Geſner and Aldrovandus appeared, the knowledge of Nature, like other branches of literature, was in⯑volved in the general gloom of ignorance and ſuperſtition. It was the object of theſe authors [vii] to amaſs every thing that had been ſaid of ani⯑mals by poets, ſhepherds, grammarians, philo⯑ſophers, phyſicians, and old women. Their pro⯑lixity, of courſe, is inſufferable. Their labours, however, may be regarded as rude quarries, from which ſome valuable materials may be dug up; but the expence of removing the rubbiſh will, perhaps, overbalance their intrinſic value.
In the ſame claſs, with little exception, may be ranked, Wotton, Belon, Rondeletius, Salvia⯑nus, Johnſon, and a multitude of ſimilar writers. They all tranſcribed, and ſometimes abridged, the labours of their predeceſſors; but they uni⯑formly loſt ſight of philoſophy and ſcience.
This race of phlegmatic writers was ſuc⯑ceeded by our celebrated countrymen Mr Ray and Mr Willoughby, who were admirers of Nature, and lamented the ſlovenly dreſs in which ſhe had been generally exhibited. They knew the value of her treaſures, and wiſh⯑ed to ſhow them in their native brilliancy. They rejected dubious and fictious relations. They added, from obſervation and experiment, many new facts: They arranged animals under proper claſſes and ſubdiviſions: They deſcribed with accuracy and preciſion: They pointed out the importance of the ſcience, and recommended the ſtudy of it by the ſolidity and clearneſs of their views, and by the brevity and perſpicuity of their compoſitions. This taſte continued ſome time, and produced the works of Reaumur, Trembley, Buffon, and ſimilar publications.
[viii] From beginnings ſo proſperous much was to be expected. But the excellency of method was no ſooner recogniſed, than the philoſophy of the ſcience was nearly extinguiſhed by a profuſion of new terms and arrangements. The juſtly ce⯑lebrated Linnaeus, by perſevering induſtry, join⯑ed to the utility of his technical Dictionary*, unfortunately turned the attention of moſt na⯑turaliſts, though contrary to the learned author's deſign, from the great views of Nature to the humble ambition of ſyſtem-making. It is need⯑leſs to ſpecify examples. Every philoſopher muſt have obſerved, with regret, that inundation of methodical diſtributions which have ſucceſ⯑ſively appeared during the courſe of theſe laſt thirty or forty years. Since the publiſhing of Linnaeus's works, the attention of Naturaliſts has been principally occupied with criticiſing former arrangements, and fabricating new ones. The philoſophy of the ſcience has, of courſe, been almoſt totally neglected. It has been ex⯑hibited in its moſt forbidding aſpect, which has limited the ſtudy of it to a few, and thoſe often not of the moſt brilliant talents; for it has been remarked, that the parade of learning, reſulting from technical phraſes and definitions, allure ſome men to become what is called great natu⯑raliſts, whoſe chief knowledge of Nature con⯑ſiſts [ix] in the knack of being able to name, with facility, a great number of her productions.
This propenſity toward multiplying metho⯑dical diſtributions, and diſputing about their re⯑ſpective merits, has brought much obloquy on the ſcience of Nature. Men of ſenſe perceive the folly of diſcuſſions concerning the local ſi⯑tuation of an animal in a book. They conſider the authors as learned triflers; and, what is worſe, they are apt to regard a ſubject, which affords no better entertainment or information, as barren and unprofitable. To no other ſource are to be aſcribed the following ſentiments, ſo frequently expreſſed by men of no inconſide⯑rable talents: 'That natural hiſtorians have ſel⯑dom diſcovered extenſive views; that they confine their chief attention to the mere tech⯑nical part of the ſcience; that they rarely take notice of manners and inſtincts, or the cauſes and oeconomy of animal action; and that they never purſue theſe great and uſeful objects with a degree of taſte and philoſophical ac⯑curacy, proportioned to the importance of the ſubject.' Theſe ſtrictures are common: It were to be wiſhed that they had no foundation in truth.
In natural hiſtory, two ends only can be at⯑tained by ſyſtem. Both of them are uſeful, but extremely different in their kinds. Syſtem may be employed either to facilitate the diſtinc⯑tion [x] of objects, or to aſcertain their relations in the ſcale of being.
The firſt ſpecies of ſyſtem, it is obvious, muſt conſiſt entirely of a ſeries of external or inter⯑nal characters. It is of little moment, whe⯑ther the objects ranked under particular OR⯑DERS be mutually connected; becauſe, if we may judge from the many laborious, but a⯑bortive attempts which have been made, Na⯑ture ſeems not to have expreſſed ſuch con⯑nections in characters recogniſable by our ſenſes. A ſyſtem ſo limited in its principles and deſign, can never aſſume any other form than that of a technical index or dictionary. If the general and particular characters be ſo marked, that a ſtudent, after learning the diviſions and language of the author, can inveſtigate the proper names of the objects preſented to him, then is this ſy⯑ſtem perfect; becauſe its ſole and primary in⯑tention is fulfilled.
Were every naturaliſt of the ſame ſentiments with regard to this point, many incumbrances, which now load the ſcience, would be removed; the tyro would not be diſguſted and retarded by an infinity of ſynonimes; natural hiſtory would acquire a more ſimple and intelligible form; and the number of its votaries would ſoon be aug⯑mented.
The ſecond ſpecies of ſyſtem is more elevated and ſublime. But, as it includes the whole phi⯑loſophy of Nature, it requires a depth of judg⯑ment, a ſuperiority of genius, an extent of know⯑ledge, [xi] which are ſeldom united in the ſame perſon. Natural objects are wonderfully diver⯑ſified in their ſtructure, oeconomy, and faculties. But, in theſe, as well as in many other circum⯑ſtances, they are no leſs wonderfully connected. Here, then, are foundations for conſtructing the ſyſtem of Nature. To mark the diſtinctions, to inveſtigate the relations, to aſcertain the great chain that unites the numerous tribes which people and adorn the univerſe, would demand talents ſuperior, perhaps, to thoſe of humanity. We ought not, however, to deſpair. Hardly any bounds can be ſet to the combined force of different minds acting ſucceſſively upon the ſame ſubject. Something has already been done. More may in time appear: Nature, in ſome fu⯑ture period, may happily unite Philoſophy and Natural Hiſtory, a phaenomenon which has hi⯑therto been but partially exhibited.
Among thoſe authors, whether antient or mo⯑dern, who have contributed to unfold the phi⯑loſophy of Natural Hiſtory, the COUNT DE BUFFON holds the moſt diſtinguiſhed rank. This learned and eloquent writer has introduced into his ſubjects a greater variety of diſquiſition, and given more comprehenſive views of Nature, than any preceeding or contemporary hiſtorian. His facts are, in general, collected with judg⯑ment and fidelity; and his reaſonings and in⯑ferences are not only bold and ingenious, but adorned with all the beauties of expreſſion, and [xii] all the charms of novelty. They every where lead to reflections which are momentous and in⯑tereſting. They expand the mind and baniſh prejudices. They create an elevation of thought, and cheriſh an ardour of inquiry. They open many great and delightful proſpects of the oeco⯑nomy of Nature, of the alterations and acci⯑dents to which ſhe is liable, of the cauſes of her improvement or degeneration, and of the gene⯑ral relations that connect the whole, and give riſe to all the diverſities which characteriſe and conſtitute particular orders of exiſtence*.
[xiii] The original work, of which a tranſlation is now attempted, was undertaken and carried in⯑to execution under the munificent encourage⯑ment of a great monarch. The deſign was to compoſe a hiſtory which ſhould record not only every phaenomenon in the univerſe that was al⯑ready known; but to examine, deſcribe, and delineate from the life, all the animals which could be procured by royal influence. A plan ſo extenſive required the joint operation of, at leaſt, two perſon; the one to compoſe the hi⯑ſtorical part, the other to diſſect and minutely deſcribe every animal, both native and foreign, that ſhould be obtained. The literary character and philoſophic talents of the COUNT DE BUF⯑FON pointed him out for the execution of the firſt department, and the acuteneſs and anato⯑mical ſkill of M. DAUBENTON, recommended him for that of the ſecond.
Three volumes of this great work were given to the public in the year 1749. Theſe volumes exhibited ſuch diſplays of learning, taſte, genius, and eloquence, as procured to the author un⯑common admiration, and excited a ſtrong and general deſire for the completion of his plan; which however, from various cauſes, was not accompliſhed till the year 1767.
[xiv] The COUNT DE BUFFON, in the year 1776, favoured the world with a ſupplementary vo⯑lume to his hiſtory of quadrupeds, which, beſide an ingenious diſſertation on Mules, contains re⯑lations and figures of ſeveral new animals, and valuable additions to moſt of thoſe deſcribed in the original publication.
It would be improper to enter more minutely into the hiſtory or contents of this magnificent work. Such is the fertility of the author's ge⯑nius, and ſuch his ardour for philoſophic inqui⯑ry, that, when treating of the moſt common a⯑nimals, he often aſtoniſhes his reader with the profoundneſs of his remarks, and the beauty of his analogical diſcuſſions.
But, though the publication was a great ac⯑quiſiſition to literature; yet the high price of SIXTEEN GUINEAS, which was an unavoidable conſequence of its ſplendour, and of the prodi⯑gious number of its elegant engravings, confined its utility to men of opulence. Senſible of this inconvenience, the COUNT DE BUFFON, a few years ago, publiſhed an edition in 12mo; and, to bring it within the reach of common purcha⯑ſers, he excluded from it the long and minute anatomical diſſections and menſurations.
After this ſhort ſketch of the COUNT DE BUFFON's Hiſtory of Nature, it may ſeem ſtrange that no decent tranſlation of it has hitherto ap⯑peared in the Engliſh language. To ſuch an undertaking, the great expence of the engravings [xv] was one ſolid objection. Another aroſe from the vaſt variety of learning employed by the author. When to theſe are added the exube⯑rance of his fancy, the eloquence and force of his diction, the delicacy and acuteneſs of his diſ⯑quiſitions, we ſhould rather wonder how any man could reconcile himſelf to a taſk ſo labo⯑rious, and which required the union of ſuch di⯑verſified talents.
The tranſlation which is now ſubmitted to the judgment and candour of the public, was projec⯑ted and begun about ſeven years ago. The tran⯑ſlator, unſuſpicious of rivals, proceeded with de⯑liberation. When the ingenious Dr Goldſmith's Natural Hiſtory appeared, ſome aſſiſtance was expected, as he tranſlates many paſſages from Buffon. But this expectation was abortive; for Dr Goldſmith, though he follows our author in general, omits and patches according to his own fancy, ſeldom giving any article entire, or in or⯑der, and never exerting thoſe talents as a tran⯑ſlator which he employs ſo ſucceſsfully in his o⯑riginal compoſitions.
Dr Goldſmith's Natural Hiſtory, however, ſuggeſted to ſome bookſellers the idea of a cheap tranſlation of Buffon's Hiſtory of Quadrupeds. The preſent tranſlator, knowing the difficulty and labour of his undertaking, was naturally alarm⯑ed [xvi] when he ſaw this new publication announced. But, upon the peruſal of it, he was ſurpriſed to find, that, in many places, it was nearly a literal tranſcript of the paſſages which Dr Goldſmith had tacked together to anſwer his own views, without intending to tranſlate, or to exhibit fully the ideas of Buffon*. By this manufacture, entire paſſages of the original, pages, ſometimes to the extent of ten or a dozen†, the whole ſupplementary Volume, all the ſynonimes and de⯑ſcriptions, and moſt of the authorities, are omit⯑ted. Of courſe, the reaſonings of the author are rendered inconcluſive; his narrative is thrown into confuſion; and his obſervations are rendered incoherent. Above 130 copper⯑plates are alſo omitted; all thoſe which illuſtrate [xvii] the experiments on generation being of this number. The Tranſlators, beſides, as is evident from a thouſand inſtances, were unacquainted with the ſubjects which were treated, and could not expreſs ſentiments which they did not under⯑ſtand* The ſtyle, too, is not only ſlovenly [xviii] and inaccurate, but often perfectly unintelligible. In a word, this tranſlation muſt be, and actually is, conſidered by every intelligent reader, as a [xix] mere literary impoſition. It is painful to mark the blunders of other men; and, were it not for a regard to literature, and to the reputation of the COUNT DE BUFFON, no notice ſhould have been taken of this ſtrange performance. But the examples given in the notes will fully juſti⯑fy the ſeeming ſeverity of theſe ſtrictures.
The following tranſlation comprehends what is contained in the original fifteen volumes in quarto, together with the ſupplementary volume to the hiſtory of quadrupeds, excepting the de⯑ſcription of the King's cabinet, the dry and un⯑intereſting anatomical diſſections and menſura⯑tions, which can be of little uſe but to profeſſed anatomiſts, and have been properly omitted by the author in the laſt Paris edition. The me⯑thod of ſtudying Natural Hiſtory; the repre⯑henſion of methodical diſtributions; and the mode of deſcribing animals, are likewiſe omitted. The chief intention of theſe diſcourſes is to ridi⯑cule the authors of ſyſtematic arrangements, and particularly the late ingenuous and indefatigable Sir Charles Linnaeus, whoſe zeal and labours in promoting the inveſtigation of natural objects merit the higheſt applauſe. There is a ſtronger reaſon for this omiſſion: The ſame remarks and arguments are, perhaps, too frequently repeated in the hiſtory of particular animals.
To render this Engliſh verſion more valuable, the tranſlator has added ſhort diſtinctive deſcrip⯑tions to each ſpecies of quadrupeds. For theſe [xx] he has been indebted to the labours of the learn⯑ed and ingenious Mr Pennant, who has alſo, with that politeneſs, and diſintereſted regard to ſcience, which ought always to adorn the gentle⯑man and the ſcholar, frankly permitted the en⯑graving of ſeveral new animals from his excel⯑lent Synopſis*. Beſide theſe uſeful additions, the ſynonimes, and the generic and ſpecific cha⯑racters given by Linnacus, Klein, Briſſon, and other naturaliſts, are ſubjoined to the deſcrip⯑tion of each ſpecies.
Where the author commits miſtakes, or where he recommends practices, regarding the ma⯑nagement of particular animals, which differ from thoſe obſerved in this country, the tranſla⯑tor has taken the liberty of animadverting upon ſuch paſſages in notes: But he has ſeldom ta⯑ken any notice of peculiar theories or doctrines. Theſe muſt reſt upon the facts and arguments employed by the author. It was not the inten⯑tion of the tranſlator to write a commentary upon his original.
The great variety of ſubjects diſcuſſed by the Count de Buffon, has already been mentioned. It is unneceſſary to remark, that every ſubject demands a peculiar ſtyle. A bare enumera⯑tion of facts, or deſcriptions of the dimenſions, figure, and colour of animals, admit of no other ornament than that of perſpicuity. Topics of philoſophy and argument require a higher and [xxi] more figurative expreſſion: And addreſſes to the paſſions, and the finer feelings of men, give full ſcope to the exerciſe of genius and taſte. Of theſe different ſpecies of writing, the examples are numerous in the works of the COUNT DE BUFFON. The tranſlator has endeavoured to follow the original, as far as his abilities would permit. The degree of ſucceſs he has attained muſt be ſubmitted to the impartial determination of the public. He ſhall only ſay, that his ap⯑prehenſions, though he is conſcious of no vo⯑luntary negligence, are much greater than his hopes.
In the dimenſions of animals, the tran⯑ſlator has retained the French meaſures. The differences between the foot or inch of England and France are ſo inconſiderable, when applied to in⯑dividual animals, that he thought it unneceſſary to reduce them to the preciſe Engliſh ſtandard, eſpecially as the dimenſions are Engliſh in the deſcriptions added in the notes.
EDIN. Jan. 10. 1780.
THE figure of the earth*, its motions, or the external relations which ſubſiſt be⯑tween it and the other parts of the univerſe, be⯑long not to our preſent inquiry. It is the inter⯑nal ſtructure of the globe, its form and manner of exiſtence, that we here propoſe to examine. The general hiſtory of the earth ought to precede that of its productions. Details of particular facts relating to the oeconomy and manners of animals, or to the culture and vegetation of plants, are not, perhaps, ſo much the objects of natural hiſtory, as general deductions from the obſervations that have been made upon the dif⯑ferent materials of which the earth itſelf is com⯑poſed; as its heights, depths, and inequalities; the motions of the ſea, the direction of moun⯑tains, the ſituation of rocks and quarries, the ra⯑pidity and effects of currents in the ocean, &c. [2] This is the hiſtory of nature at large, and of her principal operations, by which every other infe⯑rior or leſs general effect is produced. The the⯑ory of theſe effects conſtitutes what may be cal⯑led the primary ſcience, upon which a preciſe knowledge of particular appearances, as well as of terreſtrial ſubſtances, ſolely depends. This ſpecies of ſcience may be conſidered as apper⯑taining to phyſics; but, is not all phyſical know⯑ledge, where ſyſtem is excluded, a part of the hiſtory of nature?
In ſubjects of an extenſive kind, the relations of which it is difficult to trace, where ſome facts are but partially known, and others ob⯑ſcure, it is more eaſy to form a fanciful ſyſtem, than to eſtabliſh a rational theory. Thus the theory of the earth has never hitherto been treated but in a vague and hypothetical manner. I ſhall, therefore, exhibit only a curſory view of the notions of ſome authors who have writ⯑ten upon this ſubject.
The firſt hypotheſis I ſhall mention is more conſpicuous for its ingenuity than ſolidity. It is the production of an Engliſh aſtronomer*, who was an enthuſiaſtic admirer of Sir Iſaac Newton's ſyſtem of philoſophy. Convinced that every poſſible event depends upon the mo⯑tions and direction of the ſtars, he endeavours to prove, by means of mathematical calculations, [3] that all the changes this earth has undergone have been produced by the tail of a comet.
For another hypotheſis we are indebted to a heterodox divine*, whoſe brain was ſo fully im⯑pregnated with poetical illuſions, that he ima⯑gined he had ſeen the univerſe created. After telling us the ſtate of the earth when it firſt ſprung from nothing, what changes have been introduced by the deluge, what the earth has been, and what it now is, he aſſumes the prophetic ſtyle, and predicts what will be its condition af⯑ter the deſtruction of the human kind.
A third writer†, a man of more extenſive ob⯑ſervation than the two former, but equally crude and confuſed in his ideas, explains the principal appearances of the globe by the aid of an im⯑menſe abyſs in the bowels of the earth; which, in his eſtimation, is nothing but a thin cruſt in⯑cloſing this vaſt ocean of fluid matter.
Theſe unſtable hypotheſes are all conſtructed on tottering foundations. The ideas they con⯑tain are indiſtinct, the facts are confounded, and the whole is amotely jumble of phyſics and fa⯑ble. They, accordingly, have never been a⯑dopted but by people who embrace opinions without examination, and who, incapable of diſtinguiſhing the degrees of probability, are more deeply impreſſed with marvellous chime⯑ras than with the force of truth.
[4] Our ideas on this ſubject will be leſs extraor⯑dinary, and may appear unimportant when com⯑pared with the grand ſyſtems juſt mentioned. But it ought not to be forgotten, that it is the buſineſs of an hiſtorian to deſcribe, not to in⯑vent; that no gratuitous ſuppoſitions are to be admitted in ſubjects that depend upon fact and obſervation; and that, in hiſtorical compoſitions, the imagination cannot be employed, unleſs for the purpoſe of combining obſervations, of ren⯑dering facts more general, and of forming a connected whole, which preſents to the mind clear ideas, and probable conjectures: I ſay, pro⯑bable; for it is impoſſible to give demonſtrative evidence on this ſubject. Demonſtration is con⯑fined to the mathematical ſciences. Our know⯑ledge in phyſics and natural hiſtory depends en⯑tirely on experience, and is limited to the me⯑thod of reaſoning by induction.
With regard to the hiſtory of the earth, there⯑fore, we ſhall begin with ſuch facts as have been univerſally acknowledged in all ages, not omit⯑ting thoſe additional truths that have fallen with⯑in our own obſervation.
The ſurface of this immenſe globe exhibits to our obſervation heights, depths, plains, ſeas, marſhes, rivers, caverns, gulfs, volcano's; and, on a curſory view, we can diſcover, in the diſ⯑poſition of theſe objects, neither order nor re⯑gularity. If we penetrate into the bowels of the earth, we find metals, minerals, ſtones, bitumens, [5] ſands, earths, waters, and matter of every kind, placed as it were by mere accident, and without any apparent deſign. Upon a nearer and more attentive inſpection, we diſcover ſunk moun⯑tains*, caverns filled up, ſhattered rocks, whole countries ſwallowed up, new iſlands emerged from the ocean, heavy ſubſtances placed above light ones, hard bodies incloſed within ſoft bo⯑dies; in a word, we find matter in every form, dry and humid, warm and cold, ſolid and brittle, blended in a chaos of confuſion, which can be compared to nothing but a heap of rubbiſh, or the ruins of a world.
Theſe ruins, however, we inhabit with per⯑fect ſecurity. The different generations of men, of animals, and of plants, ſucceed one another without interruption: The productions of the earth are ſufficient for their ſuſtenance; the mo⯑tions of the ſea, and the currents of the air, are regulated by fixed laws†; the returns of the ſea⯑ſons are uniform, and the rigours of winter in⯑variably give place to the verdure of the ſpring. With regard to us, every thing has the appear⯑ance of order: The earth, formerly a chaos, is now a tranquil, an harmonious, a delightful ha⯑bitation, where all is animated and governed by ſuch amazing diſplays of power and intelligence, [6] as fill us with admiration, and elevate our minds to the contemplation of the great Creator.
But, let us not decide precipitantly concern⯑ing the irregularities on the ſurface of the earth, and the apparent diſorder in its bowels: We ſhall ſoon perceive the utility, and even the neceſſity of this arrangement. With a little attention, we ſhall perhaps diſcover an order of which we had no conception, and general relations which cannot be apprehended by a ſlight examination. Our knowledge, indeed, with regard to this ſub⯑ject, muſt always be limited. We are entirely unacquainted with many parts of the ſurface of this globe*, and have but very partial ideas con⯑cerning the bottom of the ocean, which, in ma⯑ny places, has never been ſounded. We can only penetrate the rind of the earth. The greateſt caverns†, the deepeſt mines‡, deſcend not above the 8th thouſandth part of its diame⯑ter. Our judgment is therefore confined to the upper ſtratum, or mere ſuperficial part. We know, indeed, that, bulk for bulk, the earth is four times heavier than the ſun: We likewiſe know the proportion its weight bears to that of the other planets. But ſtill this eſtimation is only relative. We have no ſtandard. Of the real weight of the materials we are ſo ignorant, that the internal part of the globe may be either [7] a void ſpace, or it may be compoſed of matter a thouſand times heavier than gold. Neither is there any method of making farther diſcoveries on this ſubject. It is even with difficulty that rational conjectures can be formed*.
We muſt therefore confine ourſelves to an ac⯑curate examination and deſcription of the ſurface of the earth, and of ſuch inconſiderable depths as we have been able to penetrate. The firſt object which attracts the attention, is that im⯑menſe body of water with which the greateſt part of the globe is covered. Theſe waters oc⯑cupy the loweſt grounds; their ſurface is always level; and, notwithſtanding their uniform ten⯑dency to equilibrium and reſt, they are kept in perpetual agitation by a powerful agent†, which counteracts their natural tranquility, which com⯑municates to them a regular periodic motion, al⯑ternately elevating and depreſſing their waves, and which produces a concuſſion or vibration in the whole maſs, even to the moſt profound depths. This motion of the water is coeval with time, and will endure as long as the ſun and and moon, which are the cauſes of it.
In examining the bottom of the ſea, we per⯑ceive it to be equally irregular as the ſurface of the dry land‡. We diſcover hills and valleys, plains and hollows, rocks and earths of every [8] kind*: We diſcover, likewiſe, that iſlands are nothing but the ſummits of vaſt mountains, whoſe foundations are buried in the ocean†; we find other mountains whoſe tops are nearly on a level with the ſurface of the water; and rapid currents which run contrary to the gene⯑ral movement‡. Theſe currents ſometimes run in the ſame direction; at other times their mo⯑tion is retrograde‖; but they never exceed their natural limits, which ſeem to be as immutable as thoſe which bound the efforts of land-rivers. On one hand, we meet with tempeſtuous re⯑gions, where the winds blow with irreſiſtible fury, where the heavens and the ocean, equally convul⯑ſed, are mixed and confounded in the general ſhock; violent inteſtine motions, tumultuous ſwel⯑lings§, water-ſpouts**, and ſtrange agitations, produced by volcano's, whoſe mouths, though many fathoms below the ſurface, vomit forth torrents of fire, and puſh, even to the clouds, a thick vapour, compoſed of water, ſulphur, and bitumen; and dreadful gulphs or whirl⯑pools††, which ſeem to attract veſſels for no o⯑ther purpoſe than to ſwallow them up. On the other hand, we diſcover vaſt regions of an [9] oppoſite nature, always ſmooth and calm, but equally dangerous to the mariner*. Here the winds never exert their force; the nautical art is of no utility; the becalmed voyagers muſt re⯑main immoveably fixed, till death relieve them from miſery. To conclude, directing our eyes toward the ſouthern or northern extremities of the globe, we diſcover huge maſſes of ice†, which, detaching themſelves from the polar re⯑gions, advance, like floating mountains, to the temperate climates, where they diſſolve and va⯑niſh from our view‡.
Beſide theſe grand objects, the ocean preſents us with myriads of animated beings, almoſt in⯑finite in variety: Some clothed in light ſcales, ſwim with amazing ſwiftneſs; others, loaded with thick ſhells, trail heavily along, leaving their traces in the ſand: To others nature has given ſins reſembling wings, with which they ſupport themſelves in the air, and fly before their enemies to conſiderable diſtances. Laſtly, the ſea gives birth to other animals, that, totally deprived of motion, live and die immoveably fixed to the ſame rocks: All, however, find a⯑bundance of food in this fluid element. The bottom of the ocean, and the ſhelving ſides of rocks, produce plentiful crops of plants of many different ſpecies; its ſoil is compoſed of ſand, gravel, rocks, and ſhells; in ſome places, it is a fine clay, in others, a compact earth; and, in gene⯑ral, [10] the bottom of the ſea has an exact reſem⯑blance to the dry land which we inhabit.
Let us next take a view of the land: What prodigious differences take place in different climates? What a variety of ſoils! what inequa⯑lities in the ſurface! But, upon a more attentive obſervation, we will perceive, that the great chains of mountains lie nearer the equator than the poles*; that, in the Old Continent, their di⯑rection is more from eaſt to weſt than from ſouth to north; and that, on the contrary, in the New Continent, they extend more from north to ſouth than from eaſt to weſt. But, what is ſtill more remarkable, the figure and direction of theſe mountains, which have a moſt irregular appearance†, correſpond ſo wonderfully, that the prominent angles of one mountain are conſtant⯑ly oppoſite to the concave ‡ angles of the neigh⯑bouring mountain‖, and of equal dimenſions, whether they be ſeparated by an extenſive plain, or a ſmall valley. I have further remarked, that oppoſite hills are always nearly of the ſame height; and that mountains generally occupy the middle of continents, iſlands, and promon⯑tories, dividing them by their greateſt lengths§. I have likewiſe traced the courſes of the princi⯑pal rivers, and find that their direction is near⯑ly perpendicular to the ſea-coaſts into which they empty themſelves; and that, during the [11] greateſt part of their courſes, they follow the direction of the mountains from which they de⯑rive their origin*. The ſea-coaſts are general⯑ly bordered with rocks of marble, and other hard ſtones, or rather with earth and ſand accumu⯑lated by the waters of the ſea, or brought down and depoſited by rivers. In oppoſite coaſts, ſepa⯑rated only by ſmall arms of the ſea, the different ſtrata or beds of earth are of the ſame materials†. I find that volcano's never exiſt but in high mountains‡; that a great number of them are entirely extinguiſhed; that ſome are connec⯑ted to others by ſubterranean paſſages, and their eruptions not unfrequently happen at the ſame time‖. There are ſimilar communications be⯑tween certain lakes and ſeas. Some rivers ſud⯑denly diſappear§, and ſeem to precipitate them⯑ſelves into the bowels of the earth. We likewiſe find certain mediterranean or inland ſeas, that con⯑ſtantly receive, from many and great rivers, pro⯑digious quantities of water, without any aug⯑mentation of their bounds, probably diſcharging by ſubterraneous paſſages all thoſe extraneous ſupplies. It is likewiſe eaſy to diſtinguiſh lands which have been long inhabited, from thoſe new countries where the earth appears in a rude ſtate, where the rivers are full of cataracts, where the land is either nearly overflowed with water, or burnt up with drought, and where every place [12] capable of producing trees is totally covered with wood.
Proceeding in our examination, we diſcover that the upper ſtratum of the earth is univerſal⯑ly the ſame ſubſtance*; that this ſubſtance, from which all animals and vegetables derive their growth and nouriſhment, is nothing but a compoſition of the decayed parts of animal and vegetable bodies, reduced into ſuch ſmall particles that their former organic ſtate is not diſtinguiſhable. Penetrating a little deeper, we find the real earth, beds of ſand, lime-ſtone, clay, ſhells, marble, gravel, chalk, &c. Theſe beds are always parallel to each other†, and of the ſame thickneſs through their whole extent. In neighbouring hills, beds or ſtrata of the ſame materials are uniformly found at the ſame le⯑vels, though the hills be ſeparated by deep and large valleys. Strata of every kind, even of the moſt ſolid rocks, are uniformly divided by per⯑pendicular fiſſures‡. Shells, ſkeletons of fiſhes, marine plants, &c. are often found in the bowels of the earth, and on the top of mountains‖, even at the greateſt diſtances from the ſea. Theſe ſhells, fiſhes, and plants, are exactly ſimilar to thoſe which exiſt in the ocean. Petrified ſhells are to be met with, almoſt every wher, in prodigious quantities: They are not only in⯑cloſed in rocks of marble and lime-ſtone, as [13] well as in earths and clays, but are actually in⯑corporated and filled with the very ſubſtances in which they are incloſed. In fine, I am con⯑vinced, by repeated obſervation, that marbles, lime-ſtones, chalks, marles, clays, ſand, and al⯑moſt all terreſtrial ſubſtances, wherever ſitua⯑ted, are full of ſhells and other ſpoils of the ocean*.
Having enumerated theſe facts, let us try what concluſions can be drawn from them.
The changes which the earth has undergone, during the laſt two or three thouſand years, are inconſiderable, when compared with the great revolutions which muſt have taken place in thoſe ages that immediately ſucceeded the creation. For, as terreſtrial ſubſtances could not acquire ſolidity but by the continued action of gravity, it is eaſy to demonſtrate, that the ſurface of the earth was at firſt much ſofter than it is now; and, conſequently, that the ſame cauſes which at preſent produce but ſlight, and almoſt imperceptible alterations during the courſe of many centuries, were then capable of produ⯑cing very great revolutions in a few years. It appears, indeed, to be an uncontravertible fact, that the dry land which we now inhabit, and even the ſummits of the higheſt mountains, were formerly covered with the waters of the ſea; for ſhells, and other marine bodies, are [14] ſtill found upon the very tops of mountains. It likewiſe appears, that the waters of the ſea have remained for a long track of years upon the ſur⯑face of the earth; becauſe, in many places, ſuch immenſe banks of ſhells have been diſcovered, that it is impoſſible ſo great a multitude of ani⯑mals could exiſt at the ſame time. This circum⯑ſtance ſeems likewiſe to prove, that, although the materials on the ſurface of the earth were then ſoft, and, of courſe, eaſily diſunited, moved, and tranſported, by the waters; yet theſe tranſportations could not be ſuddenly ef⯑fected. They muſt have been gradual and ſuc⯑ceſſive, as ſea-bodies are ſometimes found more than 1000 feet below the ſurface. Such a thickneſs of earth or of ſtone could not be ac⯑cumulated in a ſhort time. Although it ſhould be ſuppoſed, that, at the deluge, all the ſhells were tranſported from the bottom of the ocean, and depoſited upon the dry land; yet, beſide the difficulty of eſtabliſhing this ſuppoſition, it is clear, that, as ſhells are found incorporated in marble, and in the rocks of the higheſt moun⯑tains, we muſt likewiſe ſuppoſe, that all theſe marbles and rocks were formed at the ſame time, and at the very inſtant when the deluge took place; and that, before this grand revolu⯑tion, there were neither mountains, nor marbles, nor rocks, nor clays, nor matter of any kind ſi⯑milar to what we are now acquainted with, as they all, with few exceptions, contain ſhells, [15] and other productions of the ocean. Beſide, at the time of the univerſal deluge, the earth muſt have acquired a conſiderable degree of ſolidity, by the action of gravity for more than ſixteen centuries. During the ſhort time the deluge laſted, it is, therefore, impoſſible, that the waters ſhould have overturned and diſſolved the whole ſurface of the earth, to the greateſt depths that mankind have been able to penetrate.
But, without inſiſting longer on this point, which ſhall afterwards be more fully canvaſſed, I ſhall confine myſelf to known and eſtabliſhed facts. It is certain, that the waters of the ſea have, at ſome period or other, remained for a ſucceſſion of ages upon what we now know to be dry land; and, conſequently, that the vaſt continents of Aſia, Europe, Africa, and Ameri⯑ca, were then the bottom of an immenſe ocean, replete with every thing which the preſent ocean produces. It is likewiſe certain, that the diffe⯑rent ſtrata of the earth are horizontal, and pa⯑rallel to each other*. This parallel ſituation muſt, therefore, be owing to the operation of the waters, which have gradually accumulated the different materials, and given them the ſame poſition which water itſelf invariably aſſumes. The horizontal poſition of ſtrata is almoſt uni⯑verſal: In plains, the ſtrata are exactly horizon⯑tal. It is only in the mountains that they are inclined to the horizon; becauſe they have ori⯑ginally [16] been formed by ſediments depoſited up⯑on an inclined baſe. Now, I maintain, that theſe ſtrata muſt have been gradually formed, and are not the effect of any ſudden revolution; becauſe nothing is more frequent than ſtrata compoſed of heavy materials placed above light ones, which never could have happened, if, according to ſome authors, the whole had been blended and diſſolved by the deluge, and afterwards pre⯑cipitated. On this ſuppoſition, every thing would have had a different aſpect from what now appears. The heavieſt bodies would have deſcended firſt, and every ſtratum would have had a ſituation correſponding to its ſpecific gravity. In this caſe, we ſhould not have ſeen ſolid rocks or metals placed above light ſand, nor clay under coal.
Another circumſtance demands our attention. No other cauſe than the motion and ſediments or water could poſſibly produce the regular po⯑ſition of the various ſtrata of which the ſuperfi⯑cial part of this earth is compoſed. The higheſt mountains conſiſt of parallel ſtrata, as well as the loweſt valleys. Of courſe, the formation of mountains cannot be imputed to the ſhocks of earthquakes, or to the eruptions of volcano's. Such ſmall eminences as have been raiſed by volcano's or convulſions of the earth, inſtead of being compoſed of parallel ſtrata, are mere maſ⯑ſes of weighty material, blended together in the [17] utmoſt confuſion.*. But this parallel and hori⯑zontal poſition of ſtrata muſt neceſſarily be the operation of a uniform and conſtant cauſe.
We are, therefore, obliged to conclude, from repeated and uncontrovertible facts and obſer⯑vations, that the dry and habitable part of the earth has remained for a long time under the waters of the ſea, and muſt have undergone the ſame fluctuation and changes which are preſent⯑ly going on at the bottom of the ocean. To diſcover, therefore, what has formerly happen⯑ed to the dry land, let us examine what paſſes in the bottom of the ſea; and we ſhall ſoon be enabled to make ſome rational concluſions with regard to the external figure, and internal con⯑ſtitution of the earth.
The ocean, from the creation of the ſolar ſy⯑ſtem, has been conſtantly ſubject to a regular flux and reflux. This motion, which happens twice in twenty-four hours, is principally occa⯑ſioned by the action of the moon, and is greater in the equatorial regions than in other climates. The earth likewiſe performs a rapid motion on its axis, and, conſequently, has a centrifugal force, which is alſo greateſt at the equator. This laſt circumſtance, independent of actual obſervations, proves, that the earth is not a per⯑fect ſphere, but that it muſt be more elevated under the equator than at the poles. From theſe two combined cauſes, the tides, and the motion [18] of the earth, it may be fairly concluded, that, al⯑though this globe had been originally a perfect ſphere, its diurnal motion, and the ebbing and flowing of the tides, muſt neceſſarily, in a ſuc⯑ceſſion of time, have elevated the equatorial parts, by gradually carrying mud, earth, ſand, ſhells, &c. from other climates, and depoſiting them at the equator*. On this ſuppoſition, the greateſt inequalities on the ſurface of the earth ought to be found, and, in fact, are found, in the neighbourhood of the equator. Beſides, as the alternate motion of the tides has been con⯑ſtant and regular ſince the exiſtence of the world, is it not natural to think, that, at each tide, the water carries from one place to ano⯑ther a ſmall quantity of matter, which falls to the bottom as a ſediment, and forms thoſe hori⯑zontal and parallel ſtrata that every where ap⯑pear? The motion of the waters, in the flux and reflux, being always horizontal, the matter tranſported by them muſt neceſſarily take the ſame parallel direction after it is depoſited.
To this, it may be objected, that, as the flux is equal to, and regularly ſucceeded by the re⯑flux, the two motions will blance each other; or, that the matter brought by the flux will be carried back by the reflux; and, conſequently, that this cauſe of the formation of ſtrata muſt be chimerical, as the bottom of the ocean can never be affected by a uniform alternate motion [19] of the waters; far leſs could this motion change its original ſtructure, by creating heights, and other inequalities.
But, in the firſt place, the alternate motion of the waters is by no means equal; for the ſea has a continual motion from eaſt to weſt: Be⯑ſide, the agitations occaſioned by the winds, pro⯑duce great inequalities in the tides. It will like⯑wiſe be acknowledged, that, by every motion in the ſea, particles of earth, and other mate⯑rials, muſt be carried from one place, and de⯑poſited in another; and that theſe collections of matter muſt aſſume the form of parallel and horizontal ſtrata. Farther, a well known fact will entirely obviate this objection. On all coaſts, where the ebbing and flowing are diſ⯑cernible*, numberleſs materials are brought in by the flux, which are not carried back by the reflux. The ſea gradually increaſes on ſome places, and recedes from others, narrowing its limits, by depoſiting earth, ſand, ſhells, &c. which naturally take a horizontal poſition. Theſe materials, when accumulated and eleva⯑ted to a certain degree, gradually ſhut out the water, and remain for ever in the form of dry land.
But, to remove every doubt concerning this important point, let us examine more cloſely the practicability of a mountain's being formed at the bottom of the ſea, by the motion and ſe⯑diments [20] of the water. On a coaſt which the ſea waſhes with violence during the flow, ſome part of the earth muſt be carried off by every ſtroke of the waves. Even where the ſea is bounded by rock, it is a known fact, that the rock is gradually waſted by the water*; and, conſequently, that ſmall particles are carried off by the retreat of every wave. Thoſe particles of earth or ſtone are neceſſarily tranſported to ſome diſtance. Whenever the agitation of the water is abated, the particles are precipitated in the form of a ſediment, and lay the foundation of a firſt ſtratum, which is either horizontal, or inclined, according to the ſituation of the ſur⯑face upon which they fall. This ſtratum will ſoon be ſucceeded by a ſimilar one, produced by the ſame cauſe; and thus a conſiderable quantity of matter will be gradually amaſſed, and diſpoſed in parallel beds. In proceſs of time, this gradually accumulating maſs will be⯑come a mountain in the bottom of the ſea, ex⯑actly reſembling, both in external and internal ſtructure, theſe mountains which we ſee on the dry land. If there happened to be ſhells in that part of the bottom of the ſea where we have ſuppoſed the ſediments to be depoſited, they will be covered, filled, and incorporated with the depoſited matter, and form a part of the general maſs. Theſe ſhells will be lodged in different parts of the mountains, correſpon⯑ding [21] to the times they were depoſited. Thoſe which lay at the bottom, before the firſt ſtratum was formed, will occupy the loweſt ſtation; and thoſe which were afterwards depoſited, will be found in the more elevated parts.
In the ſame manner, when the bottom of the ſea, at particular places, is troubled by the agi⯑tation of the water, earth, clay, ſhells, and other matter, muſt neceſſarily be removed from theſe parts, and depoſited elſewhere. For we are aſ⯑ſured by all divers, that the bottom of the ſea, at the greateſt depths to which they deſcend*, is ſo ſtrongly affected by the agitation of the water, that earth, clay, and ſhells, are removed to great diſtances. Tranſportations of this kind muſt, therefore, be conſtantly going on in every part of the ocean; and the matters tranſported, after ſubſiding, muſt uniformly raiſe eminences ſimilar, in every reſpect, to the compoſition and ſtructure of our mountains. Thus the motions produced by the flux and reflux, by winds and currents, muſt uniformly create inequalities in the bottom of the ocean.
Further, we muſt not imagine that theſe matters cannot be carried to great diſtances, ſince we daily find grain, and other productions of the Eaſt and Weſt Indies, arriving on our coaſts† Theſe bodies are, indeed, ſpecifically lighter than water; but the other ſubſtances [22] are ſpecifically heavier. Still, however, as they are reduced to an impalpable powder, they may be kept long ſuſpended in the water, and, of courſe, tranſported to any diſtance.
It has been conceived, that the agitation pro⯑duced by the winds and tides is only ſuperficial, and does not affect the bottom, eſpecially when it is very deep. But it ought to be remember⯑ed, that, whatever be the depth, the whole maſs is put in motion by the tides at the ſame time; and that, in a fluid globe, this motion would be communicated even to the centre. The power which occaſions the flux and reflux is penetra⯑ting; it acts equally upon every particle of the maſs; ſo that the quantity of its force, at diffe⯑rent depths, may be determined by calculation. Indeed, this point is ſo certain, that it admits not of diſpute.
We cannot, therefore, heſitate in pronouncing, that the tides, the winds, and every other cauſe of motion in the ſea, muſt produce heights and inequalities in its bottom; and that theſe emi⯑nences muſt uniformly be compoſed of regular ſtrata, either horizontal or inclined. Theſe heights will gradually augment; like the waves which formed them, they will mutually reſpect each other; and, if the extent of the baſe be great, in a track of years, they will form a vaſt chain of mountains. Whenever eminences are formed, they interrupt the uniform motion of the waters, and produce new motions, known [23] by the name of currents. Between two neigh⯑bouring heights in the bottom of the ocean, there muſt be a current*, which will follow their common direction, and, like a river, cut a channel, the angles of which will be alternately oppoſite through the whole extent of its courſe. Theſe heights muſt continually increaſe; for, during the flow, the water will depoſite its or⯑dinary ſediment upon their ridges, and the wa⯑ters which are impelled by the current will force along, from great diſtances, quantities of matter, which will ſubſide between the hills, and, at the ſame time, ſcoup out a valley with correſponding angles at their foundation. Now, by means of theſe different motions and ſediments, the bot⯑tom of the ocean, though formerly ſmooth, muſt ſoon be furrowed, and interſperſed with hills and chains of mountains, as we actually find it at preſent. The ſoft materials of which the eminences were originally compoſed, would gradually harden by their own gravity. Such of them as conſiſted of ſandy and cryſtalline particles, would produce thoſe enormous maſſes of rock and flint in which we find cryſtals and other precious ſtones. Others, compoſed of ſto⯑ny particles mixed with ſhells, give riſe to thoſe beds of lime-ſtone and marble, in which vaſt quantities of ſea-ſhells are ſtill found incorpora⯑ted. Laſtly, all our beds of marle and chalk have derived their origin from particles of ſhells mix⯑ed [24] with a pure earth, collected and depoſited at particular places in the bottom of the ſea. All theſe ſubſtances are diſpoſed in regular ſtrata; they all contain heterogenous matter, and vaſt quantities of ſea-bodies ſituated nearly in pro⯑portion to their ſpecific gravities. The lighter ſhells are found in chalk; the heavier in clay and lime-ſtone. Theſe ſhells are uniformly fill⯑ed with the matter in which they are found, whether it be ſtone or earth; an inconteſtible proof, that they have been tranſported along with the matter which fills and ſurrounds them, and that this matter was then in the form of an impalpable powder. In a word, all thoſe ſub⯑ſtances, the horizontal ſituation of which has a⯑riſen from the waters of the ſea, invariably pre⯑ſerve their original poſition.
It may here be objected, that moſt hills whoſe ſummits conſiſt rocks of moor-ſtone, or of marble, are founded upon ſmall eminences, compoſed of leſs heavy materials, of clay, for ex⯑ample, or of light ſand, the ſtrata of which com⯑monly extend over the neighbouring plains. If the above theory be juſt, what could bring a⯑bout an arrangement ſo ſingular, ſo contrary to the laws of gravity? But this phaenomenon ad⯑mits of an eaſy and natural explication. The waters would operate firſt upon the upper ſtra⯑tum, either of coaſts, or the bottom of the ſea: This upper ſtratum conſiſts generally of clay or ſand; and theſe light ſubſtances, being carried [25] off and depoſited previous to the more denſe and ſolid, they would of courſe from ſmall eminen⯑ces, and become foundations for the more hea⯑vy particle to reſt upon. After the light ſuper⯑ficial ſubſtances are removed, the harder and more ponderous would next be ſubjected to the attrition of the water, reduced to a fine powder, and carried off and depoſited above the hillocks of ſand or clay. Theſe ſmall ſtony particles would, in a ſucceſſion of ages, form thoſe ſolid rocks which we now find on the tops of hills and mountains. As particles of ſtone are heavier than ſand or clay, it is probable that they were originally covered and preſſed by ſuperior ſtra⯑ta of conſiderable depth; but that they now oc⯑cupy the higheſt ſtations, becauſe they were laſt tranſported by the waves.
To confirm this reaſoning, let us inveſtigate more minutely the ſituation of thoſe materials which compoſe the ſuperficial part of the globe, the only part of which we have any adequate knowledge. The different ſtrata of ſtones in quarries are almoſt all horizontal or regualrly in⯑clined. Thoſe founded upon hard clay, or o⯑ther ſolid matter, are evidently horizontal, e⯑ſpecially in plains. The diſpoſition of quarries, where flint or browniſh free-ſtone are found in detached portions, is indeed leſs regular. But even here the uniformity of nature is not inter⯑rupted; for the horizontal or regularly inclining poſition of the ſtrata is apparent in granite and [26] brown free-ſtone, wherever they exiſt in large connected maſſes. This poſition is univerſal, excepting in flint and brown free-ſtone in ſmall detached portions, ſubſtances, the formation of which we ſhall demonſtrate to have been poſterior to thoſe juſt now mentioned. The ſtrata of gra⯑nite, vitrifiable ſand, clays, marbles, calcareous ſtones, chalk, and marles, are always parallel or equally inclined. In theſe the original forma⯑tion is eaſily diſcoverable; for the ſtrata are ex⯑actly horizontal, and very thin, being placed a⯑bove each other like the leaves of a book. Beds of ſand, of ſoft and hard clay, of chalk, and of ſhells, are likewiſe either horizontal or uniform⯑ly inclined. Strata of every kind preſerve the ſame thickneſs through their whole extent, which is often many leagues, and might, by proper obſervations, be traced ſtill farther. In a word, the diſpoſition of ſtrata, as deep as mankind have hitherto penetrated, is the ſame.
Thoſe beds of ſand and gravel which are waſhed down from mountains muſt, in ſome meaſure, be excepted from the general rule. They are ſometimes of a conſiderable extent in valleys, and are ſituated immediately under the ſoil, or firſt ſtratum. In plains, they are level, like the more antient and interior ſtrata. But near the bottom, or upon the ridges of hills, they have an inclination correſponding to that of the ground upon which they have been de⯑poſited. As theſe beds of ſand and gravel are [27] formed by rivers and brooks, which, eſpecially in the valleys, often change their channels, it is not ſurpriſing that they ſhould be ſo frequent. A ſmall rivulet is ſufficient, in a courſe of time, to ſpread a bed of ſand or gravel over a very large valley. In a champaign country, ſurround⯑ed with hills, whoſe baſe, as well as the upper ſtratum of the plain, conſiſted of a hard clay, I have often obſerved, that, above the origin of the brooks or rivers, the clay was ſituated imme⯑diately under the vegetable ſtratum; but, in the low grounds, there was a ſtratum of ſand, about a foot thick above the clay, extending to a great diſtance from the banks of the rivers. The ſtrata formed by rivers are not very antient; they are eaſily diſtinguiſhed by their frequent inter⯑ruptions, and the inequality in thickneſs, which is conſtantly varying; but the antient ſtrata uniformly preſerve the ſame dimenſions through their whole extent. Beſides, theſe modern ſtrata may be diſtinguiſhed, with certainty, by the form of the ſtones and gravel they contain, which bear evident marks of having been roll⯑ed, ſmoothed, and rounded by the motion of water. The ſame obſervation may be made with regard to thoſe beds of turf, and corrupted ve⯑getables, which are found in marſhy grounds, immediately below the ſoil: They have no claim to antiquity, but have derived their exiſtence from ſucceſſive accumulations of decayed trees, and other plants. The ſtrata of ſlime, or mud, [28] which occur in many places, are alſo recent pro⯑ductions, having been formed by ſtagnating wa⯑ters, or the inundations of rivers. They are not ſo exactly horizontal, or ſo uniformly inclined, as the more antient ſtrata, produced by the re⯑gular motions of the ſea. In ſtrata formed by rivers, we meet with river, but ſeldom with ſea ſhells; and the few that occur are broken, de⯑tached, and placed without order. But, in the antient ſtrata, there are no river-ſhells; the ſea⯑ſhells are numerous, well preſerved, and all pla⯑ced in the ſame manner, having been tranſport⯑ed and depoſited at the ſame time, and by the ſame cauſe. From whence could this beautiful regularity proceed? Inſtead of regular ſtrata, why do we not find the matters compoſing the earth huddled together without order? Why are not rocks, marbles, clays, marles, &c. ſcattered promiſcuouſly, or joined by irregular or vertical ſtrata? Why are not heavy bodies uniformly found in a lower ſituation than light ones? It is eaſy to perceive, that this uniformity of nature, this ſpecies of organization, this union of diffe⯑rent materials by parallel ſtrata, without regard to their weights, could only proceed from a cauſe equally powerful and uniform as the mo⯑tions of the ſea, produced by regular winds, or by the flux and reflux, &c.
Theſe cauſes act with ſuperior force under the equator than in other climates; for there the tides are higher, and the winds more uni⯑form. [29] The moſt extenſive chains of mountains are likewiſe in the neighbourhood of the equa⯑tor. The mountains of Africa and Peru are the higheſt in the world, often extending through whole continents, and ſtretching to great diſtan⯑ces under the waters of the ocean. The moun⯑tain of Europe and Aſia, which extend from Spain to China, are not ſo elevated as thoſe of Africa and South America. According to the relations of voyagers, the mountains of the north are but ſmall hills, when compared to the moun⯑tains of the equatorial regions. Beſides, in the northern ſeas, there are few iſlands; but, in the Torrid Zone, they are innumerable. Now, as iſlands are only the ſummits of mountains, it is apparent, that there are more inequalities on the ſurface of the earth, near the equator, than in northerly climates.
Thoſe prodigious chains of mountains which run from weſt to eaſt in the Old Continent, and from north to ſouth in the New, muſt have been formed by the general motion of the tides. But the origin of the leſs conſiderable mountains and hills, muſt be aſcribed to particular mo⯑tions, occaſioned by winds, currents, and other irregular agitations of the ſea: Their formation may, indeed, be owing to a combination of all thoſe motions, which are capable of infinite va⯑riations; for the winds, and the ſituation of different iſlands and coaſts, conſtantly change the natural courſe of the tides, making them [30] run in every poſſible direction. It is, therefore, by no means ſurpriſing to ſee conſidrable eminences having no determined direction in their courſes. But, for our preſent purpoſe, it is ſufficient to have ſhown, that mountains have not been produced by earthquakes, or other ac⯑cidental cauſes, but that they are effects equally reſulting from the general laws of nature, as their peculiar ſtructure, and the ſituation of the materials of which they are compoſed.
But how has it happened, that this earth, which we and our anceſtors have inhabited for ages, which, from time immemorial, has been an immenſe continent, dry, compact, and re⯑moved from the reach of the water, ſhould, if formerly the bottom of an ocean, be now ex⯑alted to ſuch a height above the waters, and ſo compleatly ſeparated from them? Since the wa⯑ters remaiend ſo long upon the earth, why have they now deſerted it? What accident, what cauſe, could introduce a change ſo great? Is it even poſſible to conceive a cauſe poſſeſſed of power ſufficient to operate ſuch an amazing ef⯑fect?
Theſe are difficult queſtions. But, as the facts are uncontrovertible, the preciſe manner in which they have happened may remain a ſe⯑cret, without prejudice to the concluſions which ought to be drawn from them. A little re⯑flection, however, will furniſh us at leaſt with [31] plauſible ſolutions*. We daily obſerve the ſea gaining ground on certain coaſts, and loſing it on others. We know, that the ocean has a ge⯑neral and uniform motion from eaſt to weſt; that it makes violent efforts againſt the rocks and low grounds which encircle it; that there are whole provinces which human induſtry can hardly defend from the fury of the waves; and that there are inſtances of iſlands which have but lately emerged from the waters, and of re⯑gular inundations. Hiſtory informs us of in⯑undations and deluges of a more extenſive na⯑ture. Ought not all this to convince us, that the ſurface of the earth has experienced very great revolutions, and that the ſea may have ac⯑tually given up poſſeſſion of the greateſt part of the ground which it formerly occupied? For example, let us ſuppoſe, that the Old and New worlds were formerly but one continent, and that, by a violent earthquake, the antient Ata⯑lantis of Plato was ſunk. What would be the conſequence of ſuch a mighty revolution? The ſea would neceſſarily ruſh in from all quarters, and form what is now called the Atlantic Ocean; and vaſt continents, perhaps thoſe which we now inhabit, would, of courſe, be left dry. This great revolution might be effected by the ſudden failure of ſome immenſe cavern in the interior part of the globe, and an univerſal deluge would infallibly ſucceed. I would rather incline to [32] think, that ſuch a revolution would not be ſud⯑denly accompliſhed, but that it required a very long period. However theſe conjectures ſtand, it is certain, that the revolution has happened, and I even believe that it happened naturally; for, if a judgment of the future is to be formed from the paſt, we have only to attend carefully to what daily paſſes before our eyes. It is a fact, eſtabliſhed by the repeated obſervation of voyagers, that the ocean has a conſtant motion from eaſt to weſt. This motion, like the trade⯑winds, is not only perceived between the tropics, but through the whole temperate cli⯑mates, and as near the poles as navigators have approached. As a neceſſary conſequence of this motion, the Pacific Ocean muſt make continual efforts againſt the coaſts of Tartary, China, and India; the Indian Ocean muſt act againſt the eaſt coaſt of Africa; and the Atlantic muſt act in a ſimilar manner againſt all the eaſtern coaſts of America. Hence the ſea muſt have gained, and will always continue to gain on the eaſt, and to loſe on the weſt. This of itſelf would be ſuf⯑ficient to prove the poſſibility of the change of ſea into land, and of land into ſea. If ſuch is the natural effect of the ſea's motion from eaſt to weſt, may it not reaſonably be ſuppoſed, that Aſia, and all the eaſtern continent, is the moſt antient country in the world? and that Europe, and part of Africa, eſpecially the weſt parts of theſe continents, as Britain, France, Spain, &c. [33] are countries of a more recent date? Both hiſto⯑ry and phyſics concur in eſtabliſhing this hypo⯑theſis.
But, beſides the conſtant motion of the ſea from eaſt to weſt, other cauſes concur in produ⯑cing the effect juſt mentioned. There are many lands lower than the level of the ſea, and de⯑fended only by a narrow iſthmus of rock, or by banks of ſtill weaker materials. The action of the waters muſt gradually deſtroy theſe barriers, and, conſequently, ſuch lands muſt then become part of the ocean. Beſides, the mountains are daily diminiſhing, part of them being conſtantly carried down to the valleys by rains. It is like⯑wiſe well known, that every little brooke carries earth, and other matters, from the high grounds into the rivers, by which they are at laſt tranſ⯑ported to the ocean. By theſe means, the bot⯑tom of the ſea is gradually filling up, the ſur⯑face of the earth is approaching to a level, and nothing but time is wanting for the ſea's ſucceſ⯑ſively changing places with the land.
I ſpeak not here of cauſes removed beyond the ſphere of our knowledge, of thoſe convul⯑ſions of nature, the ſlighteſt throe of which would be fatal to the globe. The near approach of a comet, the abſence of the moon, or the in⯑troduction of a new planet into the ſyſtem, &c. are ſuppoſitions upon which the imagination may rove at large. Cauſes of this kind will produce any effect we chuſe. From a ſingle hy⯑potheſis [34] of this nature, a thouſand phyſical ro⯑mances might be drawn, and their authors might dignify them with the title of Theory of the Earth. As an hiſtorian, I reject theſe vain ſpe⯑culations: They depend upon mere poſſibilities, which, if called into action, neceſſarily imply ſuch a devaſtation in the univerſe, that our globe, like a fugitive particle of matter, eſcapes our obſervation, and is no longer worthy of our attention. But, to give conſiſtency to our ideas, we muſt take the earth as it is, examine its dif⯑ferent parts with minuteneſs, and, by induction, judge of the future, from what at preſent exiſts. We ought not to be affected by cauſes which ſeldom act, and whoſe action is always ſudden and violent. Theſe have no place in the ordi⯑nary courſe of nature. But operations uniform⯑ly repeated, motions which ſucceed one another without interruption, are the cauſes which alone ought to be the foundation of our reaſoning.
Some examples ſhall be given: We ſhall com⯑bine particular effects with general cauſes, and give a detail of facts, which will illuſtrate and explain the different alterations that the earth has undergone, whether by irruptions of the ſea upon the land, or by the ſea's retiring from lands which it formerly covered.
That irruption which gave riſe to the Medi⯑terranean*, is undoubtedly the greateſt†. The [35] ocean runs with prodigious rapidity through a narrow paſſage between two promontories*, and then forms a vaſt ſea, which, excluſive of the Black Sea, is about ſeven times larger than the kingdom of France. The motion through the Straits of Gibraltar is contrary to the motion in every other ſtrait. The general motion of the ſea is from eaſt to weſt; but, in the Straits of Gibraltar, it is from weſt to eaſt: An inconteſ⯑tible proof, that the Mediterranean Sea is not an antient gulf, but that it has been formed by an irruption, produced by ſome accidental cauſe, ſuch as an earthquake ſwallowing up the bar⯑rier, or a violent effort of the ocean, occaſioned by the wind's forcing its way through the bank, between the two promotories of Gibraltar and Ceuta. This opinion is ſupported by the teſti⯑mony of the antients†, who inform us, that there was a time when the Mediterranean had no exiſtence. It is likewiſe confirmed by na⯑tural hiſtory, and by obſervations upon the ſtrata in the oppoſite coaſts of Africa and Spain, where, as in neighbouring mountains, the beds of earth and ſtone are preciſely the ſame at the ſame levels.
When the ocean forced this paſſage, it ran through the Straits with much more rapidity than at preſent, and inſtantly deluged that large tract of land which formerly jointed Europe to [36] Africa. The waters covered all the grounds which were lower than the level of the ocean; and no part of them is now to be ſeen, except the tops of ſome of the mountains, ſuch as part of Italy, Sicily, Malta, Corſica, Sardinia, Cy⯑prus, Rhodes, and the iſlands of the Archipe⯑lago.
I have not mentioned the Black Sea as an ef⯑fect of this irruption; becauſe the quantity of water it receives from the Danube, the Nieper, the Don, and other rivers, is more than ſuffi⯑cient both to form and ſupport it. Beſides, it runs with great rapidity through the Boſphorus into the Mediterranean*. It may even be ſup⯑poſed, that the Black and Caſpian Seas were on⯑ly two large lakes, which were perhaps joined by a narrow communication, or rather by a mo⯑raſs, or ſmall lake, uniting the Don and the Wolga about Tria, where theſe two rivers run very near each other. It is likewiſe probable, that theſe two ſeas, or lakes, were formerly of a much greater extent; for the large rivers which fall into the Black and Caſpian Seas muſt have gradually brought down a quantity of earth and ſand ſufficient to ſtop up the communication, and to form that neck of land by which theſe two ſeas are divided. We know, that large ri⯑vers, in a courſe of time, block up ſeas, and form new lands, as in the province at the mouth of the Yellow river in China; Louiſiana at the [37] mouth of the Miſſiſippi; and the northern part of Aegypt, which derived its exiſtence* from the inundations of the Nile†. Such quantities of earth are brought down, by the rapidity of the Nile, from the interior parts of Africa, and de⯑poſited during the inundations, that you may dig fifty feet deep before you can reach the bot⯑tom of the ſlime and mud. Louiſiana, and the province of the Yellow river have, in the ſame manner, been original formed by the ſlime of rivers.
Farther, the Caſpian Sea is a real lake. It has no communication with any other ſea, not even with the Lake Aral, which appears to have been a part of it, being only ſeparated by a large tract of ſand, in which neither river nor canal for carrying off the waters have been diſcovered. This ſea, therefore, has no external communica⯑tion with any other; and I doubt much if there is any reaſon to ſuſpect a ſubterraneous commu⯑nication with the Black Sea, or with the Gulf of Perſia. The Caſpian, it is true, receives the Wolga, and ſeveral other rivers, which appear to furniſh as much water as is loſt by evapora⯑tion. But, independent of the difficulties attend⯑ing ſuch calculations, if it communicates with any other ſea, a uniform and rapid current towards the place of communication would be an infal⯑lible conſequence; but no ſuch thing has yet been diſcovered. Travellers of the beſt credit [38] aſſure us of the contrary; we, therefore, con⯑clude, that the Caſpian Sea receives juſt as much water from the rivers and clouds as it loſes by evaporation.
It is not improbable, that the Black Sea will, ſome time or other, be entirely divided from the Mediterranean; and that the Boſphorus will be chocked up, whenever the rivers ſhall have ac⯑cumulated a ſufficient quantity of materials to bring about that effect. It is impoſſible to ſix the aera of this event; but time, and the dimi⯑nution of waters in rivers, in proportion as the mountains are lowered by the cauſes mentioned above, will one day exhibit this phaenomenon to the world.
The Caſpian and Black Seas ſhould, there⯑fore, be conſidered rather as lakes than as gulfs of the ocean; becauſe they exactly reſemble o⯑ther lakes that receive a number of rivers with⯑out any viſible outlet, as the Dead Sea, ſeveral lakes in Africa, and elſewhere. Beſides, the ſalt⯑neſs of theſe two ſeas is not nearly equal to that of the Mediterranean or the ocean; and it is an agreed point, that the navigation in the Caſpian and Black ſeas, on account of their numberleſs ſhoals, rocks, and banks, is ſo extremely hazard⯑ous, that only ſmall veſſels can be uſed in them with ſafety. This circumſtance proves farther, that theſe ſeas ought not to be conſidered as gulfs of the ocean, but as vaſt collections of water a⯑maſſed by large rivers.
[39] If the iſthmus which ſeparates Africa from Aſia were cut, it would neceſſarily create a great irruption of the ſea upon the land. This was formerly projected by the Kings of Aegypt, and adopted ſince by the Califs. I doubt whether the pretended communication between the Red Sea and Mediterranean be ſufficiently eſtabliſhed. The Red Sea is a narrow branch of the ocean: Through its whole extent, not a ſingle river runs into it from the Aegyptian ſide, and very few from the oppoſite. This ſea will not, therefore, be ſubject to diminution, like thoſe ſeas or lakes which are actually impaired by the ſlime and ſand brought down by large rivers. The Red Sea receives all its waters directly from the o⯑cean, and the motion of the tides in it are very diſcernible; of courſe, it muſt be affected by the general motions of the ocean. The Mediterra⯑nean, on the other hand, muſt be lower than the ocean; becauſe the current through the Straits is exceedingly rapid. Beſides, it receives the Nile, which runs parallel to the weſt coaſt of the Red Sea, and paſſes through the longeſt extent of Aegypt, which is a very low country. From theſe circumſtances, it is at leaſt probable, that the Red Sea is higher than the Mediterranean, and, conſequently, that, if the iſthmus of Suez were cut, a great inundation, and a conſiderable augmentation of the Mediterranean, would en⯑ſue; eſpecially if the waters were not reſtrained by dikes and ſluices placed at proper diſtances. [40] This precaution was probably uſed, if ever the antient canal exiſted.
But, not to ſpend too much time on conjec⯑tures, which, however well founded, may per⯑haps appear raſh, we ſhall give ſome certain and recent examples of the changes of ſea into land, and of land into ſea*. At Venice, the bottom of the ſea is conſtantly riſing: If the canals had not been carefully kept clean, the moats and ci⯑ty would, long ere now, have formed a part of the continent. The ſame thing may be ſaid of moſt harbours, bays, and mouths of rivers. In Holland, the bottom of the ſea is elevated in ma⯑ny places; the gulf of Zuderzee and the ſtraits of the Texel, cannot receive ſuch large veſſels as formerly. At the mouth of almoſt every ri⯑ver, we find ſmall iſlands, and banks of earth and ſand brought down from the higher grounds; and it is uncontravertible, that the ſea is con⯑ſtantly dammed up, wherever great rivers empty themſelves. The Rhine is loſt in the ſands which itſelf has accumulated. The Danube, the Nile, and all large rivers, after having tranſport⯑ed great quantities of ſlime, ſand, &c. never more arrive at the ſea by a ſingle channel; they ſplit into branches, the intervals of which conſiſt of the materials which they themſelves have tranſ⯑ported. Marſhes are daily drained; lands, a⯑bandoned by the ſea, are now plowed and ſown; we navigate whole countries now covered by the [41] waters; in a word, we ſee ſo many inſtances of land changed into water, and water into land, that we muſt be convinced of the continual, though ſlow progreſs of ſuch changes in all pla⯑ces. So that, in time, the gulfs of the ocean will become continents; the iſthmuſes will be chan⯑ged into ſtraits; and the tops of the mountains will be metamorphoſed into ſhoaly rocks in the ſea.
The waters, then, have covered, and may ſtill cover, every part of the earth which is now dry. Our aſtoniſhment at finding the productions of the ſea diſperſed every where, and a compoſition of bodies which could not be effected by any o⯑ther means than the operation of the waters, ought forever to ceaſe. We have already ex⯑plained how the horizontal ſtrata of the earth were formed. But thoſe perpendicular ſiſſures, which are equally diffuſed through rocks, clays, and every conſtituent material of the globe, re⯑main to be conſidered. The perpendicular fiſ⯑ſures are indeed placed at greater diſtances from each other than the horizontal; and the ſofter the matter, the more diſtant are the fiſſures. In marble and hard ſtone, the fiſſures are only a few feet aſunder. If the maſs of rock be ex⯑tenſive, the diſtance betwixt the fiſſures is ſome fathoms: Sometimes they extend from the ſum⯑mit to the baſe of the rock, and ſometimes they terminate after arriving at a horizontal fiſſure. They are uniformly perpendicular in the ſtrata [42] of all calcareous ſubſtances, as chalk, marles, marble, &c. But they are more oblique and leſs regularly ſituated, in vitreſcent bodies, brown free-ſtone, and rocks of flint, where they are often adorned with cryſtals and other minerals. In quarries of marble, or of calcareous ſtone, the fiſſures at filled with ſpar, gypſum, gravel, and an earthy ſand, which contains a conſiderable portion of chalk. In marles, and every other ſpecies of earth, except ſand-ſtone, the perpen⯑dicular fiſſures are either empty or filled with ſuch matters as have been tranſported thither by water.
The cauſe of perpendicular fiſſures is eaſily inveſtigated. As various materials conſtituting the different ſtrata were tranſported by the wa⯑ters, and depoſited in the form of ſediments, they would at firſt be in a very diluted ſtate, and would gradually harden and part with the ſu⯑perfluous quantity of water they contained. In the proceſs of drying, they would naturally con⯑tract, and of courſe ſplit at irregular diſtances. Theſe fiſſures neceſſarily aſſumed a perpendicu⯑lar direction; becauſe, in this direction, the ac⯑tion of gravity of one particle upon another is equal to nothing; but it acts directly oppoſite to this deſcription in a horizontal ſituation: The diminution in bulk could have no ſenſible effect but in a vertical line. I ſay, the contraction of the parts in drying, not the contained water forcing an iſſue, as has been alledged, is the cauſe [43] of perpendicular fiſſures; for I have often re⯑marked, that the ſides of thoſe fiſſures, through their whole extent, correſpond as exactly as the two ſides of a ſplit piece of wood. Their ſur⯑faces are rude and irregular; whereas, if they had taken their riſe from the motion of wa⯑ter, they would have been ſmooth and poliſhed. Hence theſe fiſſures muſt have been produced, either ſuddenly or gradually, by drying and con⯑tracting, like the cracks and fiſſures in green wood; and the greateſt part of the water the bodies contained, muſt have evaporated by the pores. In the chapter upon minerals, we ſhall demonſtrate, that ſome part of the original wa⯑ter ſtill remains in ſtones and ſeveral other ſub⯑ſtances; and that cryſtals, minerals, and ſome o⯑ther bodies, owe their exiſtence to this water.
Perpendicular fiſſures vary greatly as to the extent of their openings. Some are about half an inch, or an inch, others a foot, or two feet; ſome extend ſeveral fathoms, and give riſe to thoſe vaſt precipices which ſo frequently occur between oppoſite parts of the ſame rocks in the Alps and other high mountains. It is plain, that the fiſſures, the openings of which are ſmall, have been occaſioned ſolely by drying. But thoſe which extend ſeveral feet, are partly ow⯑ing to another cauſe; namely, the ſinking of the foundation upon one ſide, while that of the other remains firm. If the baſe ſinks but a line or two, when the height of the rock is conſide⯑rable, [44] an opening of ſeveral feet, or even fa⯑thoms, will be the conſequence. When rocks are founded on clay or ſand, they ſometimes ſlip a little to a ſide; and the fiſſures are of courſe augmented by this motion. I have not hither⯑to mentioned thoſe large openings, thoſe prodi⯑gious cuts which are to be met with in rocks and mountains: Theſe could not be produced by a⯑ny other means than the ſinking of immenſe ſubterraneous caverns that were unable longer to ſuſtain their incumbent load. But theſe cuts or intervals in mountains are not of the ſame nature with perpendicular fiſſures: They ap⯑pear to have been ports opened by the hand of nature for the communication of nations. This ſeems to be the intention of all large openings in chains of mountains, and of thoſe ſtraits by which different parts of the ocean are connec⯑ted; as the Straits of Thermopyle, of Gibral⯑tar, &c.; the gaps or ports in Mount Cauca⯑ſus, the Cordeliers, &c. A ſimple ſeparation, by the drying of the matter, could not produce this effect: Large portions of earth muſt have been ſunk, ſwallowed up, or thrown down*.
Theſe great ſinkings, though occaſioned by accidental and ſecondary cauſes†, are leading facts in the hiſtory of the earth, and have con⯑tributed greatly in changing the appearance of its ſurface. Moſt of them have been produced by ſubterraneous fires, the exploſions of which [45] give riſe to earthquakes and volcano's. The force of inflamed matter ſhut up in the bowels of the earth is irreſiſtible*. By the action of ſubterraneous fires, whole cities have been ſwal⯑lowed up, mountains, and large tracts of coun⯑try have been overturned and rendered unfit for the habitation of men. But, though this force be great, though its effects appear to be prodi⯑gious, we cannot aſſent to the opinions of ſome authors, who ſuppoſe that theſe ſubterraneous fires are only branches of an immenſe abyſs of flame in the centre of the earth. Neither do we credit the common notion, that theſe fires have their ſeat at a great depth below the ſurface; for matter cannot begin to burn, or at leaſt the in⯑flammation cannot be ſupported, without air. In examining the materials that iſſue from vol⯑cano's, even in their moſt violent eruptions, it is eaſy to perceive that the furnace is not very deep, and that the inflamed ſubſtances are the ſame with thoſe on the top of the mountain, only disfigured by calcination and the melting of the metallic particles they contain. To be convinced that the matter thrown out by vol⯑cano's do not come from any conſiderable depth, we need only attend to the height of the moun⯑tain, and conſider the immenſe force which would be neceſſary to project ſtones and mine⯑rals to the height of half a league; for Aetna, [46] Hecla, and other volcano's, have at leaſt that elevation.
Now, it is well known, that fire acts equally on all ſides; it cannot, therefore, act upwards with a force ſufficient to throw large ſtones half a league high, without an equal re-action on the baſe and ſides. But the ſides of the moun⯑tain would very ſoon be pierced and blown to pieces by this re-action; becauſe the materials of which it conſiſts are not more denſe or firm than thoſe which are projected. How, then, can it be imagined, that the cavity, which muſt be conſidered as the tube or cannon, could poſſibly reſiſt a force neceſſary to raiſe ſuch heavy bodies to the mouth of the volcano? Beſides, ſuppoſe the cavity deeper, as the external orifice is not great, it would be impoſſible for ſo large a quantity of liquid and burning matters to iſſue forth at a time, without claſhing againſt each other, and againſt the irregular ſides of the ca⯑vity; and, in paſſing through ſo long a ſpace, they would be in danger of cooling and con⯑gealing. Rivers of melted ſulphur and bitumen, projected from volcano's along with ſtones and minerals, run from the tops of the mountains into the plains. Is it natural to think, that mat⯑ter ſo fluid, ſo little able to reſiſt violent action, could be projected from a very great depth? Every obſervation which can be made on this ſubject will tend to prove, that the fire in vol⯑cano's is not very diſtant from the tops of the [47] mountains, and never deſcends ſo low as the level of the plains*.
This account of volcano's, however, is not inconſiſtent with their being the cauſe of conſi⯑derable earthquakes; neither does it contradict the communication of one volcano with ano⯑ther, by means of ſubtertaneous paſſages†. But the depth of the furnace is the object of our preſent inveſtigation; and it cannot be very diſ⯑tant from the mouth of the volcano. To pro⯑duce an earthquake in a plain, it is not neceſſary that the bottom of the volcano ſhould be below the level of that plain, nor that there ſhould be ſubterraneous cavities filled with the ſame burn⯑ing matter under it. A violent exploſion, with which eruptions are uniformly accompa⯑nied, may, like that of a powder-magazine, give ſuch a concuſſion as to produce, by its re⯑action, an earthquake of conſiderable extent.
I mean not to ſay that there are no earth⯑quakes which derive their exiſtence from ſub⯑terranean fires‡; but that there are earthquakes produced ſolely by the exploſion of volcano's. In confirmation of what has been ſaid upon this ſubject, volcano's ſeldom or never appear in plains; on the contrary, their mouths, or cra⯑ters, are always found on the tops of the high⯑eſt mountains. If the ſubterraneous fire of vol⯑cano's ſtretched below the plains, would not [48] new paſſages be opened there during violent eruptions, rather than in the tops of the moun⯑tains, where the reſiſtance is greater? In the firſt eruption, would it not have been eaſier to pierce a plain, than a mountain of half a league in height?
It is not difficult to diſcover the reaſon why volcano's appear only in mountains. Greater quantities of minerals, ſulphur, and pyrites, exiſt in mountains, and nearer the ſurface than in plains. The mountains have likewiſe this far⯑ther advantage; they are more ſubject to the impreſſions of the air, and receive more rain and moiſture, by which mineral ſubſtances are ca⯑pable of being fermented to ſuch a degree as to produce actual inflammation.
To conclude, it has often been obſerved, that, after violent eruptions, the mountains have ſunk and diminiſhed, nearly in proportion to the quantity of matter thrown out, which is another proof that volcano's are not ſo deep as the baſe of the mountains, and even that they are not much below the ſummit.
In many places, earthquakes have formed conſiderable hollows, and even ſome large gaps in mountains. All other inequalities are coeval with the mountains themſelves, and owe their exiſtence to currents in the ocean; for, in every place which has not been diſturbed by acciden⯑tal convulſions, the ſtrata of mountains are pa⯑rallel, [49] and their angles correſpond*. It is not difficult to diſtinguiſh ſubterraneous caverns and excavations formed by volcano's, from thoſe produced by water. The latter conſiſt only of ſolid rocks, the ſand and clay with which they were formerly filled being carried off by water, which is the origin of caverns in hills; for thoſe found in plains are commonly nothing but old pits and quarries, like the ſalt-quarries of Mae⯑ſtricht, the mines of Poland, &c. But natural caverns are proper to the mountains; the ſum⯑mit, or higher parts, furniſh them with water, which afterwards iſſues out to the ſurface where⯑ever it can find a paſſage. Theſe are the ſources of ſprings and rivers. When a large cavern of this kind is ſuddenly filled up by the falling of its roof, an inundation is generally the conſe⯑quence†.
From theſe facts, it is eaſy to perceive how much ſubterraneous fires have contributed to change both the ſurface and internal part of the globe. This cauſe has power enough to pro⯑duce very great effects. But it is difficult to conceive how any ſenſible alterations upon the land can be introduced by the winds‡. Their dominion would appear to be confined to the ſea. Indeed, next to the tides, nothing has ſuch a powerful influence upon the waters; the flux and reflux proceed with an uniform pace; their [50] operations are always the ſame; but the action of the winds is capricious and violent. They ruſh on with irreſiſtible fury, and excite ſuch impetuous commotions, that the ocean, from a ſmooth and tranquil plain, in an inſtant is fur⯑rowed with waves that emulate the height of mountains, and daſh themſelves in pieces againſt the ſhores. The ſurface of the ocean is ſubject to conſtant alterations from the winds. But ought not the ſurface of the land, which has ſo ſolid an appearance, ever to remain uninfluenced by a cauſe of this kind? It is conſonant to experi⯑ence, however, that the winds raiſe mountains of ſand in Arabia and Africa; that they overwhelm large plains with it; and that they frequently carry theſe ſands many leagues into the ſea, where they accumulate in ſuch quantities as to form banks, downs, and even iſlands*. It is alſo well known, that hurricanes are the ſcourge of the Antilles, of Madagaſcar, and of other coun⯑tries, where their impetuoſity is ſo great, that they ſweep away trees, plants, and animals, to⯑gether with the ſoil which nouriſhed them. They drive back, they annihilate rivers, and produce new ones; they overthrow rocks and mountains; they ſcoup out holes and gulphs in the earth, and totally change the face of thoſe unhappy countries that give birth to them. Hap⯑pily, [51] few climates are expoſed to the violence of thoſe dreadful agitations of the air.
But the greateſt changes upon the ſurface of the earth are occaſioned by rains, rivers, and tor⯑rents from the mountains. Theſe derive their origin from vapours raiſed by the ſun from the ſurface of the ocean, and which are tranſported by the winds through every climate. The pro⯑greſs of theſe vapours, which are ſupported by the air, and tranſported at the pleaſure of the winds, is interrupted by the tops of the moun⯑tains, where they accumulate into clouds, and fall down in the form of rain, dew, or ſnow. At firſt, theſe waters deſcended into the plains without any fixed courſe*; but they gradually hollowed out proper channels for themſelves. By the power of gravity, they ran to the bottom of the mountains, and, penetrating or diſſolving the lower grounds, they carried along with them ſand and gravel, cut deep furrows in the plains, and thus opened paſſages to the ſea, which al⯑ways receives as much water by rivers, as it loſes by evaporation. The windings in the channels of rivers have uniformly correſponding angles on their oppoſite banks; and, as moun⯑tains and hills, which may be regarded as the banks of the valleys by which they are ſepara⯑ted, have likewiſe ſinuoſities with correſponding angles, this circumſtance ſeems to demonſtrate, that the valleys have been gradually formed by [52] currents of the ocean, in the ſame manner as the channels of rivers have been produced.
The waters which run upon the ſurface, and ſupport the verdure and fertility of the ſoil, compoſe not perhaps one half of the quantity that is produced by vapour. Numberleſs veins of water ſink deep into the bowels of the earth. In ſome places, you are certain of obtaining water by digging; in others, none can be found. In almoſt all the valleys and low grounds, at a certain depth, water is uniformly to be met with. But, in all high grounds, it is impoſſible to extract water from the bowels of the earth. It muſt be collected from the heavens. There are extenſive countries where no wells can be obtained; there men, and other animals, are ſupplied with drink from ciſterns and pools. In the caſt, and eſpecially in Arabia, Aegypt, and Perſia, wells and ſprings are great and valuable rarities. To ſupply their place, the inhabitants have been obliged to make large reſervoirs to collect the water that falls from the heavens. Theſe works, projected and executed from public neceſſity, conſtitute the moſt beautiful and mag⯑nificent monuments of the eaſt. Some eaſtern reſervoirs have more than two ſquare leagues of ſuperficies, and fertilize whole provinces by numberleſs ducts and canals let out from all ſides. But, in plain countries, furniſhed with large ri⯑vers, it is impoſſible to break the ſurface of the earth without finding water. In camps ſituated in [53] the neighbourhood of rivers, it often happens, that every tent may have its own well, by giving a few ſtrokes with a pick-ax.
Moſt of the water, ſo liberally diffuſed through low grounds, comes from the neighbouring hills and eminences. During great rains, or the ſud⯑den melting of ſnow, part of the water runs up⯑on the ſurface; but moſt of it penetrates the earth and rocks, by means of ſmall chinks and fiſſures. This water riſes again to the ſurface, whenever it can find an iſſue; but it often drills through ſands, and creeps along till it finds a bottom of clay, or hard earth, and there forms ſubterraneous lakes, brooks, and perhaps rivers, of which the channels are for ever buried in o⯑blivion. Subterraneous rivers, however, muſt follow the general law of nature, and uniformly run from the higher to the lower ground; their waters muſt of courſe either fall at laſt into the ſea, or be collected in ſome low place, whether at the ſurface, or in the bowels of the earth: For there are ſeveral lakes which neither receive nor give riſe to any river. A ſtill greater num⯑ber receive no conſiderable river, but are the ſources of the largeſt rivers on earth; as the lakes from which the river St Laurence iſſues; the lake Chiamè, from which two large rivers ariſe, that water the kingdoms of Aſem and Pegu; the lakes of Aſſiniboil in America; thoſe of Ozera in Muſcovy; thoſe that give riſe to [54] the Bog and the Irtis, and many others*. It is plain, that theſe lakes muſt derive their exiſt⯑ence from the waters of ſuperior grounds, run⯑ning through ſubterraneous paſſages. Some, indeed, have affirmed, that lakes are to be met with on the tops of the higheſt mountains. But this is incredible; for the lakes found on the Alps, and other elevated ſituations, are all over⯑topped by higher mountains, and derive their origin from the waters which run down the ſides, or are filtered through the bowels of theſe ſuperior eminences, in the ſame manner as the lakes in valleys are ſupplied.
From this reaſoning, the exiſtence of ſubter⯑raneous collections of water, eſpecially under large plains, is apparent†: For mountains, hills, and heights of every kind, are expoſed on all ſides to the weather. The waters that fall up⯑on their ſummits, and upon elevated plains, after penetrating the earth, muſt, from the declivity of the ground, break out at many places in the form of ſprings and fountains: Of courſe, little water will be found in the bowels of mountains. But, in plains, as the water filtrated through the earth can find no iſſue, it muſt be collected in ſub⯑terraneous caverns, or diſperſed in ſmall veins, among ſand and gravel. This is the origin of the water ſo univerſally diffuſed through low grounds. The bottom of a pit or well, is only a ſmall artificial baſon, into which the water in⯑ſinuates [55] itſelf from the higher grounds. At firſt it generally falls in by drops; but afterwards, when the paſſages become more open, it receives freſh ſupplies from greater diſtances, and runs in ſmall continued veins or rills. To this cir⯑cumſtance it is owing, that, although water may be found in any part of a plain, only a certain number of wells can be ſupplied. This number is in proportion to the quantity of water diffuſed, or rather to the extent of the higher grounds from which it comes.
To find water, it is unneceſſary to dig below the level of the river. It is commonly found at ſmaller depths. The water of rivers ſeldom ſpreads far in the earth by filtration. Even what is found in the earth below the level of rivers, is not derived from them; for, in rivers which have been dried up, or whoſe courſes have been changed, no greater quantity of water is obtained by digging, than in the neighbouring ground at an equal depth. Five or ſix feet of earth is ſufficient to contain water, and to pre⯑vent its eſcape: I have often remarked, that the banks of rivulets or pools have no ſenſible moiſture at the diſtance of ſix inches from the water. It is true, the filtration is always in proportion to the penetrability of the ground. But, upon examining the ſtagnating pools with a ſandy bottom, it is remarkable that the moi⯑ſture ſpreads but a few inches. Neither is the extent of it great in a vegetable ſoil, which is [56] much more looſe and porous than ſand or hard earth. A garden-bed, though plentifully wa⯑tered, communicates little or no moiſture to thoſe adjoining. I have examined level heaps of gar⯑den-earth, of ſix or eight feet thick, which had remained undiſturbed for ſome years, and found that the rain-water had never reached above three or four feet deep. I have made the ſame obſervation upon earth which had lain 200 years in ridges: Below the depth of three or four feet, it was as dry as duſt. Hence the ſpreading of water by filtration alone, is not ſo extenſive as has generally been imagined. Very little can deſcend in this way to the bowels of the earth. But water, by its own gravity, deſcends from the ſurface to the greateſt depths. It ſinks through natural conduits, or forces paſſages for itſelf: It follows the roots of trees, the ſiſſures of rocks, or their interſtices. It divides and expands on all hands into an infinite number of ſmall branches or rills; and uniformly deſcends till its progreſs is ſtopped by clay or a ſolid earth, where it ac⯑cumulates and breaks out to the ſurface in form of a ſpring or fountain.
It would be no eaſy taſk to make an exact calculation of the quantity of ſubterraneous wa⯑ters which have no apparent iſſue*. Many pretend that it greatly ſurpaſſes all the waters on the ſurface: Not to mention thoſe who think that the interior part of the globe is entirely fill⯑ed [57] with water, it is imagined by ſome, that there is an infinite number of rivers, rills, and lakes, in the bowels of the earth. But this opi⯑nion ſeems to have no proper foundation; and it is probable, that the quantity of ſubterrane⯑ous waters which never appear at the ſurface, is very inconſiderable; for, if the number of ſub⯑terraneous rivers were ſo great, Why do we never ſee any of their mouths break out, like ſprings, on the ſurface? Beſides, rivers produce conſiderable changes on the ſurface of the earth; they carry off the ſoil; they wear away the moſt ſolid rocks, and remove every thing that oppoſes their paſſage. The ſame effects would reſult from ſubterraneous rivers. But no ſuch changes have ever been diſcovered; nothing below the ſurface is diſplaced; the different ſtrata every where preſerve their parallel and primitive poſition; and it is only in very few places that ſubter⯑raneous veins of water, of any conſideration, have been diſcovered. Thus, the internal ope⯑ration of water, though great, is not affected by the motion of it in large bodies: As it is divi⯑ded into an infinity of ſmall veins, which are often ſhut up by numberleſs obſtacles, it gives riſe to many ſubſtances, which are totally differ⯑ent, both in form and ſtructure, from thoſe of the primitive matter.
From what has been advanced, we may con⯑clude, that the flux and reflux of the ocean have produced all the mountains, valleys, and other [58] inequalities on the ſurface of the earth; that cur⯑rents of the ſea have ſcouped out the valleys, elevated the hills, and beſtowed on them their correſponding directions; that the ſame waters of the ocean, by tranſporting and depoſiting earth, &c. have given riſe to the parallel ſtrata; that the waters from the heavens gradually de⯑ſtroy the effects of the ſea, by continually di⯑miniſhing the height of the mountains, filling up the valleys, and choaking the mouths of ri⯑vers; and, by reducing every thing to its for⯑mer level, they will, in time, reſtore the earth to the ſea, which, by its natural operations, will a⯑gain create new continents, interſperſed with mountains and valleys, and every way ſimilar to thoſe which we now inhabit.
NATURAL hiſtory being our ſubject, we would willingly diſpenſe with aſtrono⯑mical obſervations. But, as the Earth is ſo near⯑ly related to the heavenly bodies, and as obſer⯑vations of this kind illuſtrate more fully thoſe doc⯑trines we have already advanced, it is neceſſary to give ſome general ideas of the formation, mo⯑tion, and figure of the earth, and other planets.
The earth is a globe of about 3000 leagues in diameter; it is ſituated 30 million of leagues from the ſun, round which it revolves in 365 days. This annual revolution is the effect of two forces; the one may be conſidered as an impulſe from right to left, or from left to right; the [60] other as an attraction from above downwards, or from below upwards, to a common centre. The direction and quantity of theſe forces are com⯑bined, and ſo nicely adjuſted, that they produce a uniform motion in an ellipſe approaching to a circle. Like the other planets, the earth is opaque, throws out a ſhadow, and reflects the rays of the ſun, about which it revolves in a time proportioned to its relative diſtance and denſity. It likewiſe revolves about its own axis in 24 hours; and its axis is inclined to the plane of its orbit 66½ degrees. Its figure is that of a ſpheroid, the two axes of which differ from each other about 165th part; and it revolves round the ſhorteſt axis.
Theſe are the principal phaenomena of the earth, the reſults of diſcoveries made by means of geometry, aſtronomy, and navigation. It is unneceſſary here to enumerate the proofs and obſervations by which theſe facts have been e⯑ſtabliſhed. We ſhall confine our remarks to ſuch objects as are ſtill doubtful; and ſhall there⯑fore proceed to give our ideas concerning the formation of planets, and the changes they have undergone, previous to their arriving at the ſtate in which we now perceive them. To the many ſyſtems and hypotheſes that have been framed concerning the formation of the earth, and the different ſtates it has paſſed through, we may be allowed to add our own conjectures, eſpecially as we are determined to ſupport them with a ſu⯑perior [61] degree of probability; and we are the more encouraged to deliver our notions on this ſubject, becauſe we hope to enable the reader to diſtinguiſh between an hypotheſis which conſiſts only of poſſibilities, and a theory ſupported by facts; between a ſyſtem, ſuch as we are about to give, of the formation and primitive ſtate of the earth, and a phyſical hiſtory of its real condition, which has been given in the preceding diſcourſe.
Galileo having traced the laws of falling bo⯑dies, and Kepler having obſerved, that the areas which the principal planets deſcribe in moving round the ſun, and thoſe of the ſatellites round the planets to which they belong, were propor⯑tioned to the periods of their revolutions, and that theſe periods were as the ſquare roots of the cubes of their diſtances from the ſun, or from the principal planets. Newton diſcovered that the power of gravity extended to the moon, and re⯑tained it in its orbit; that the force of gravity diminiſhed in exact proportion to the ſquares of the diſtances, and, conſequently, that the moon is attracted by the earth; that the earth, and all planets, are attracted by the ſun; and, in gene⯑ral, that all bodies which revolve about a centre, and deſcribe areas proportioned to the periods of their revolution, are attracted by that luminary. Gravity, therefore, is a general law of nature. The planets, comets, the ſun, the earth, are all ſubject to its laws; and it is the ſource of that harmony which prevails in the univerſe. Nothing [62] in phyſics is better eſtabliſhed than the exiſtence of this power in every material body. Repeated experience has confirmed the effects of its in⯑fluence, and the labour and ingenuity of geo⯑meters have determined its quantity and rela⯑tions.
This general law being once diſcovered, the effects of it would be eaſily explained, if the action of thoſe bodies which produce them were not too complicated. A ſlight view of the ſolar ſyſtem will convince us of the difficulties which attend this ſubject. The principal planets are attracted by the ſun, the ſun by the planets, the ſatellites by the principal planets, and each pla⯑net attracts all the others, and is attracted by them. All theſe actions and re-actions vary ac⯑cording to the quantities of matter and the di⯑ſtances, and give riſe to great inequalities, and even irregularities. How are ſo many relations to be combined and eſtimated? Among ſuch a number of objects, how is it poſſible to trace any individual? Theſe difficulties, however, have been ſurmounted; the reaſonings of theo⯑ry have been confirmed by calculation; every obſervation has produced a new demonſtration; and the ſyſtematic order of the univerſe is now laid open to every man who is able to diſtin⯑guiſh truth from error.
The force of impulſion, or what is common⯑ly called the centrifugal force, is ſtill unknown; [63] but it affects not the general theory. It is evi⯑dent, that, as the attractive force continually draws all the planets towards the ſun, they would fall in a perpendicular line into that lu⯑minary, if they were not kept at a diſtance by ſome other power, forcing them to move in a ſtraight line. If, again, this impulſive force were not counteracted by that of attraction, all the planets would fly off in the tangents of their reſpective orbits. This progreſſive or impulſive force was unqueſtionably at firſt communicated to the planets by the Supreme Being. But, in phyſical ſubjects, we ought, as much as poſſible, to avoid having recourſe to ſupernatural cauſes; and, I imagine, a probable reaſon may be aſ⯑ſigned for the impulſive force of the planets, which will be agreeable to the laws of mecha⯑nics, and not more ſurpriſing than many revolu⯑tions that muſt have happened in the univerſe.
The ſphere of the ſun's attraction is not limit⯑ed by the orbits of the planets, but extends to an indefinite diſtance, always decreaſing accor⯑ding as the ſquares of the augmented diſtances. The comets, it is evident, which eſcape our ſight in the heavenly regions, are, like the planets, ſubject to the attraction of the ſun, and by it their motions are regulated. All theſe bodies, the di⯑rections of which are ſo various, move round the ſun, and deſcribe areas proportioned to their periods, the planets in ellipſes, more or leſs cir⯑cular, and the comets, in narrow ellipſes of vaſt [64] extent. The motions, therefore, both of planets and comets, are regulated by impulſive and at⯑tractive forces continually acting upon them, and obliging them to deſcribe curves. But it is worthy of remark, that comets run through the ſyſtem in all directions; that the inclinations of the planes of their orbits are ſo very different, that though, like the planets, they be ſubject to the law of attraction, they have nothing in com⯑mon with regard to their progreſſive or impul⯑ſive motions, but appear, in this reſpect, to be abſolutely independent of each other. The pla⯑nets, on the contrary, move round the ſun in the ſame direction, and nearly in the ſame plane, the greateſt inclination of their planes not exceeding 7½ degrees. This ſimilarity in the poſition and motion of the planets indicates, that their impulſive or centrifugal forces muſt have originated from one common cauſe.
May we not conjecture, that a comet falling into the body of the ſun might drive off ſome parts from its ſurface, and communicate to them a violent impulſive force, which they ſtill retain? This conjecture appears to be as well founded as that of Mr Leibnitz, which ſuppoſed the earth and planets to have formerly been ſuns; and his ſyſtem, of which an abridgement will be given in art. V. would have been more comprehenſive, and more conſonant to probabi⯑lity, if it had embraced the above idea. We agree with him, that this effect was produced at [65] the time when God is ſaid by Moſes to have ſe⯑parated the light from darkneſs; for, according to Leibnitz, the light was ſeparated from the darkneſs when the planets were extinguiſhed. But, on our ſuppoſition, there was a real phyſi⯑cal ſeparation; becauſe the opaque bodies of the planets were detached from the luminous mat⯑ter of which the ſun is compoſed.*.
This notion concerning the cauſe of the cen⯑trifugal force of the planets will appear to be leſs exceptionable, after we have collected the analogies, and eſtimated the degrees of probabi⯑lity by which it may be ſupported. We ſhall firſt mention, that the motion of the planets have one common direction, namely, from weſt to eaſt. By the doctrine of chances, it is eaſy to demonſtrate, that this circumſtance makes it as 64 to 1, that the planets could not all move in the ſame direction, if their centrifugal forces had not proceeded from the ſame cauſe.
This probability will be greatly augmented, if we take in the ſimilarity in the inclinations of the planes of their orbits, which exceed not 7½ degrees; for, by calculations it has been diſ⯑covered, that it is 24 to 1 againſt any two pla⯑nets being found, at the ſame time, in the moſt diſtant parts of their orbits; and, conſequently, 245, or 7692624 to 1, that this effect could not [66] be produced by accident; or, what amounts to the ſame, there is this great degree of probabi⯑lity, that the planets have been impreſſed with one common moving force, from which they have derived this ſingular poſition. But no⯑thing could beſtow this common centrifugal motion, excepting the force and direction of the bodies by which it was originally communica⯑ted. We may, therefore, conclude, that all the planets have probably received their centrifugal motion by one ſingle ſtroke. Having eſtabliſh⯑ed this degree of probability, which almoſt a⯑mounts to a certainty, I next inquire what mo⯑ving bodies could produce this effect; and I can find nothing but comets capable of communica⯑ting motion to ſuch vaſt maſſes.
Upon examining the courſe of comets, it is eaſy to believe that ſome of them muſt occa⯑ſionally fall into the ſun. The comet 1680 ap⯑proached ſo near, that, at its perihelion, it was not more diſtant from the ſun than a ſixteenth part of its diameter; and, if it returns, which is extremely probable, in the year 2255, it may then fall into the ſun. This muſt depend upon the accidents it meets with in its courſe, and the retardations it ſuffers in paſſing through the ſun's atmoſphere*.
We may, therefore, preſume, with the great Newton, that comets ſometimes fall into the ſun. But they may fall in different directions. [67] If they fall perpendicularly, or in a direction not very oblique, they will remain in the body of the ſun, ſerve the purpoſes of feuel, and, by their impulſe, remove the ſun from his place, in proportion to the quantity of matter they contain* But, if a comet falls in a very o⯑blique direction, which will moſt frequently happen, it will only graze the ſurface, or pene⯑trate to no great depth. In this caſe, it may force its way paſt the ſun, detach certain por⯑tions of his body, to which it will communicate a common impulſive motion; and theſe portions puſhed off from the ſun, and even the comet itſelf, may turn planets, which will revolve round this luminary in the ſame direction, and nearly in the ſame plane. A calculation, per⯑haps, might be made of the quantity of matter, velocity, and direction, a comet ought to have, in order to force from the ſun maſſes equal to thoſe which compoſe the ſix planets and their ſatellites. But it is ſufficient here to obſerve, that the whole planets, with their ſatellites, make not a 650th part of the ſun's maſs†; for, although the denſity of Saturn and Jupiter be leſs than that of the ſun, and though the earth be four times, and the moon near five times more denſe than the ſun; yet they are only atoms when compared to his immenſe volume.
[68] It muſt be acknowledged, that, although a 650th part of a whole may ſeem inconſiderable, it would require a very large comet to detach this part from the ſun. But, if we conſider the prodigious rapidity of comets in their perihelion, the near approach they make to the ſun; the denſity and the ſtrong coheſion of parts neceſ⯑ſary to ſuſtain, without deſtruction, the incon⯑ceivable heat they undergo; and the ſolid and brilliant nucleus which ſhines through their dark atmoſpheres; it cannot be doubted that comets are compoſed of matters extremely denſe and ſolid; that they contain, in ſmall limits, a great quantity of matter; and, conſequently, that a comet of no enormous ſize may remove the ſun from his place, and give a projectile motion to a maſs of matter equal to the 650th part of his body. This remark correſponds with what we know concerning the reſpective denſities of the planets, which always decreaſe in proportion to their diſtances from the ſun, having leſs force of heat to reſiſt. Accordingly, Saturn is leſs denſe than Jupiter, and Jupiter much leſs than the earth. Thus, if the denſity of the planets, as Newton alledges, be in proportion to the quan⯑tity of heat they ſupport, Mercury will be ſeven times denſer than the earth, and 28 times denſer than the ſun, and the comet 1680 28,000 times more denſe than the earth, or 112,000 times denſer than the ſun. Now, ſuppoſing the quan⯑tity of matter in this comet to be equal to a [69] ninth part of the ſun, or, allowing it to be only 100dth part of the bulk of the earth, its quanti⯑ty of matter would ſtill be equal to a 900dth part of the ſun: Hence a body of this kind, which would be but a ſmall comet, might puſh off from the ſun a 900dth or a 650th part, eſpe⯑cially when the amazing rapidity of comets, in their perihelion, is taken into the calculation.
The correſpondence between the denſity of the whole planets, and that of the ſun, deſerves alſo to be noticed. Upon and near the ſurface of the earth, there are ſubſtances 1400 or 1500 times denſer than others; the denſities of air and gold are nearly in this proportion. But the interior parts of the earth and planets are more uniform, and differ little with regard to denſity; and the correſpondence in the denſity of the planets and that of the ſun is ſo great, that, out of 650 parts, which comprehends the whole denſity of the planets, there are more than 640 nearly of the ſame denſity with the ſolar mat⯑ter; and there are only ten of thoſe 650 that are of a ſuperior denſity; for the denſity of Sa⯑turn and Jupiter is nearly the ſame with that of the ſun; and the quantity of matter in thoſe two planets is at leaſt 64 times greater than what is contained in the four inferior planets, Mars, the Earth, Venus, and Mercury. We may, therefore, conclude, that, in general, the matter of the planets is very nearly of the ſame kind with the ſolar matter, and, of courſe, that [70] the former may have been ſeparated from the latter.
To this theory, it may be objected, that, if the planets had been driven off from the ſun by a comet, in place of deſcribing circles round him, they muſt, according to the law of projectiles, have returned to the ſame place from whence they had been forced; and, therefore, that the projectile force of the planets cannot be attribu⯑ted to the impulſe of a comet.
I reply, that the planets iſſued not from the ſun in the form of globes, but in the form of torrents, the motion of whoſe anterior particles behoved to be accelerated by thoſe behind, and the attraction of the anterior particles would al⯑ſo accelerate the motion of the poſterior; and that this acceleration, produced by one or both of theſe cauſes, might be ſuch as would neceſſa⯑rily change the original motion ariſing from the impulſe of the comet, and that, from this cauſe, might reſult a motion ſimilar to what takes place in the planets, eſpecially when it is conſidered, that the ſhock of the comets removes the ſun out of its former ſtation. This reaſoning may be illuſtrated by an example. Suppoſe a muſket⯑ball diſcharged from the top of a mountain, and that the force of the powder was ſufficient to puſh it beyond a ſemidiameter of the earth, it is certain that this ball would revolve round the earth, and return at every revolution to the place from whence it had been diſcharged. But, [71] inſtead of a muſket-ball, if a rocket were em⯑ployed, the continued action of the fire would greatly accelerate the original impulſive motion. This rocket would by no means return to the ſame point, like the ball; but, caeter is paribus, would deſcribe an orbit, the perigee of which would be more or leſs diſtant from the earth in proportion to the greatneſs of the change pro⯑duced in its direction by the accelerating force of the fire. In the ſame manner, if the original projectile force impreſſed by the comet on the torrent of ſolar matter was accelerated, it is pro⯑bable, that the planets formed by this torrent acquired their circular or elliptical movements around the ſun.
The appearances exhibited in great eruptions from volcano's may give ſome idea of this acce⯑leration of motion. When Veſuvius begins to groan and throw out inflamed matter, it has been often remarked, that the motion of the cloud firſt ejected is flower than the ſucceeding ones, and that they go on increaſing in celerity, till at laſt ſulphur, lava, melted metal, and huge ſtones are thrown up; and that, though theſe obſerve nearly the ſame direction, they alter conſider⯑ably that of the firſt cloud, and elevate it to a greater height than it would otherwiſe have reached*
[72] The objection will be ſtill farther obviated, if it is conſidered, that the impulſe of the comet muſt, in ſome degree, have communicated a mo⯑tion to the ſun, and removed it from its former ſituation; and that, although this motion may now be ſo ſmall as to eſcape the notice of aſtro⯑nomers, it may ſtill, however, exiſt, and make the ſun deſcribe a curve round the center of gra⯑vity of the ſyſtem. If this be allowed, as I pre⯑ſume it will, the planets, inſtead of returning to the ſun's body, would deſcribe orbits, the peri⯑helions of which would be as diſtant from the ſun as the ſpace which he preſently occupies is diſtant from his original ſtation.
It may be further objected, that, if motion be accelerated in the ſame direction, no change in the perihelion could take place. But, is it credible, that no change of direction can hap⯑pen in a torrent whoſe particles ſucceed each other? On the contrary, it is extremely pro⯑bable, that a change was actually produced ſuf⯑ficient to cauſe the planets move in their pre⯑ſent orbits.
It may ſtill be objected, that, if the ſituation of the ſun had been changed by the ſhock of a comet, it would move uniformly; and, of courſe, this motion being common to the whole ſyſtem, no alteration would be effected. But, previous to the ſhock, might not the ſun move round [73] the centre of the cometary ſyſtem; and might not this primary motion be augmented or dimi⯑niſhed by the ſtroke of the comet? Is not this ſufficient to account for the actual motion of the planets?
If none of theſe ſuppoſitions be admitted, may it not be preſumed, that the elaſticity of the ſun might elevate the torrent above his ſurface, in place of puſhing it directly forward? This of itſelf would be ſufficient to remove the perihe⯑lion, and endow the planets with their preſent movements. Neither is this ſuppoſition deſti⯑tute of foundation: The ſolar matter may be exceedingly elaſtic; ſince light, the only part of it we are acquainted with, ſeems, by its ef⯑fects, to be perfectly elaſtic. I acknowledge that I cannot determine which of the cauſes a⯑bove aſſigned has actually produced an altera⯑tion in the projectile force of the planets; but they at leaſt ſhow that ſuch a change is not only poſſible, but probable; and this is enough for my preſent purpoſe.
Without farther inſiſting on the objections that may be made againſt my hypotheſis, or the analogical proofs that might be brought in ſup⯑port of it, I ſhall proſecute my ſubject, and draw the proper concluſions. Let us firſt examine what might happen to the planets, and particu⯑larly to the earth, when they were impreſſed with their projectile forces, and what was their ſtate after their ſeparation from the body of the [74] ſun. A projectile motion having been commu⯑nicated by the ſtroke of a comet, to a quantity of matter equal to a 650th part of the ſun's maſs, the light particles would ſeparate from the denſe, and, by their mutual attractions, form globes of different ſolidities. Saturn being com⯑poſed of the largeſt and lighteſt parts, would be removed to the greateſt diſtance from the ſun; Jupiter, being denſer than Saturn, would have a nearer ſtation; and ſo of the reſt. The largeſt and leaſt ſolid planets are moſt diſtant, be⯑cauſe they received a greater projectile force than the ſmaller and denſer; for the projectile force being proportioned to the ſurfaces to which it is applied, the ſame ſtroke would make the larger and lighter parts of the ſolar matter move with more rapidity than the ſmaller and hea⯑vier. The parts, therefore, which differed in denſity would ſeparate from each other in ſuch a manner, that, if the denſity of the ſolar matter be equal to 100, that of Saturn will be equal to 67, of Jupiter, = 94½, of Mars, = 200, of the Earth, = 400, of Venus, = 800, of Mercury, = 2800. But, as the attractive force acts not in proportion to the ſurface, but to the quantity of matter, it would retard the progreſs of the more denſe parts of the ſolar matter; and it is for this reaſon that we find the moſt denſe pla⯑nets neareſt the ſun, and which move round him with more rapidity than thoſe that are more diſtant, and leſs denſe.
[75] The denſity and projectile motion of Saturn and Jupiter, the two largeſt planets in the ſyſtem, have the moſt exact proportion. The denſity of Saturn is to that of Jupiter as 67 to 94½, and their velocities are nearly as 88⅔ to 120 1/72, or as 67 to 90 11/16;. How rarely do pure conjectures correſpond ſo exactly to the phaenomena of na⯑ture? It is true, according to this relation be⯑tween the celerity and denſity of the planets, the denſity of the earth ought not to exceed 206 7/18, inſtead of 400, which is its real denſity; hence it may be ſuppoſed, that the earth has now double its original denſity. With regard to the other planets, Mars, Venus, and Mercury, as their denſities are only conjectural, we know not whether this circumſtance would confirm or weaken our hypotheſis. Newton ſays, that the denſities of the planets are proportioned to the degrees of heat they are expoſed to; and, it is in conſequence of this idea, that we have men⯑tioned Mars as being one time leſs denſe than the earth, Venus one time, Mercury ſeven times, and the comet 1680, 28,000 times denſer than the earth. But, if we attend to Saturn and Ju⯑piter, the two principal planets, we will find, that this ſuppoſed proportion between the den⯑ſities of the planets, and the heat they ſuſtain, is not well founded: For, according to this hy⯑potheſis, the denſity of Saturn would be as 4 7/18, and that of Jupiter as 14 17/22, inſtead of the pro⯑portions of 67 and 94½; differences ſo great as [76] to deſtroy the principles upon which they are founded. Thus, notwithſtanding the regard due to the conjectures of Newton, I cannot help thinking that the denſities of the planets have a nearer relation to their celerities than to the de⯑grees of heat to which they are expoſed. This, indeed, is only a final cauſe; but the other is a phyſical relation, the exactneſs of which is re⯑markable in Saturn and Jupiter. It is, however, certain, that the denſity of the earth, inſtead of being 206⅞, is 400; and, conſequently, the earth muſt have ſuffered a condenſation in the propor⯑tion of 206½ to 400.
But, have the condenſations of the planets no relation to the quantity of ſolar heat they ſu⯑ſtain? In that caſe, Saturn, which is at the greateſt diſtance from the ſun, would have ſuf⯑fered little or no condenſation; and Jupiter would be condenſed from 90 11/16 to 94½. Now, the ſun's heat in Jupiter being to his heat in the earth as 14 17/22 to 400, their condenſation ought to be in the ſame proportion. Thus, if Jupiter be condenſed as 90 11/16 to 94½, the earth, if it had been in the orbit of Jupiter, would have been condenſed from 206⅞ to 215 990/1452; but the earth being much nearer the ſun, and receiving heat, in proportion to that of Jupiter, as 400 to 14 17/22, the quantity of condenſation it would have undergone in the orbit of Jupiter muſt be multiplied by the proportion of 400 to 14 17/22, which will give nearly 234⅓ for the condenſa⯑tion [77] the earth muſt have received. The denſity of the earth was 206⅞; by adding its acquired condenſation, its actual denſity will be 400⅞, which is nearly the ſame with 400, its real den⯑ſity determined by the moon's parallax. With regard to the other planets, I pretend not to give exact proportions, but only approximations, tending to ſhow, that their denſities have a ſtrong connection with the celerity of their mo⯑tions in their reſpective orbits.
The comet, by falling obliquely on the ſun, as mentioned above, muſt have forced off from his ſurface a quantity of matter equal to a 650th part of his body. This matter being in a liquid ſtate, would at firſt form a torrent, of which the largeſt and rareſt parts would fly to the greateſt diſtances; the ſmaller and more denſe, having re⯑ceived only an equal impulſe, would remain nearer the ſun; his power of attraction would operate upon all the parts detached from his body, and make them circulate round him; and, at the ſame time, the mutual attraction of the particles of matter would cauſe all the detached parts to take on the form of globes, at differ⯑ent diſtances from the ſun, the nearer moving with greater rapidity in their orbits than the more remote.
But, to this it may be objected, that, if the planets had been detached from the ſun, they muſt have been burning and luminous, not cold and opaque bodies; nothing can have leſs re⯑ſemblance [78] to a globe of fire than a globe com⯑poſed of earth and water; and, by compariſon, the matter of the earth is totally different from that of the ſun.
It may be replied to this objection, that the matter changed its form upon its ſeparation, and that the fire, or light, was extinguiſhed by the projectile motion communicated by the ſtroke. Beſides, may it not be ſuppoſed, that the ſun, or a burning ſtar, moving with a rapidity equal to that of the planets, would ſoon be extinguiſhed; and that this may be the reaſon why all the luminous, or burning ſtars, are fixed, and with⯑out motion; and why thoſe called new ſtars, which have probably changed their ſtations, are frequently extinguiſhed and diſappear? To con⯑firm this remark, comets, when in their perihe⯑lia, ought to be inflamed even to their center; but they never become luminous ſtars; they on⯑ly emit a burning vapour, a conſiderable portion of which they leave behind them in their courſe.
In a medium which has little reſiſtance, I ac⯑knowledge, that fire may ſubſiſt, although the burning body be moved with great rapidity. It muſt likewiſe be acknowledged, that what I have ſaid applies only to thoſe ſtars which diſappear for ever, not to thoſe that appear and diſappear at ſtated intervals, without changing their ſitua⯑tions in the heavens. Of theſe Maupertuis, in his diſcourſe on the figure of the ſtars, has given a moſt ſatisfactory account. But thoſe [79] which have appeared, and then vaniſhed for ever, muſt unqueſtionably have been extin⯑guiſhed either by the quickneſs of their motion, or ſome other cauſe. There is not a ſingle ex⯑ample of a luminous ſtar revolving round an⯑other; and not one of the ſixteen planets which revolve round the ſun have any light in themſelves.
Farther, fire, in ſmall maſſes, cannot ſubſiſt ſo long as in large ones. The planets would burn a conſiderable time after they iſſued from the ſun; but, at length, would extinguiſh for want of combuſtible matter. For the ſame rea⯑ſon, the ſun itſelf will be extinguiſhed; but at a period as much beyond that which extinguiſhed the planets, as the quantity of matter in the ſun exceeds that of the planets. However this may be, the ſeparation of the planets from the ſun, by the ſhock of a comet, appears ſufficient to account for their extinction.
The earth and planets, when they iſſued from the ſun, were totally compoſed of liquid fire; in which ſtate they would continue no longer than the violence of the heat that kept them in fuſion. But this heat would gradually decay from the moment they left the ſun. During their fluid ſtate, they neceſſarily aſſumed circular fi⯑gures; and their diurnal motion would elevate their equators, and flatten their poles. I agree with M. Leibnitz*, that this figure correſponds [80] ſo exactly with the laws of hydroſtatics, that the earth and planets muſt neceſſarily have been once in a ſtate of fluidity occaſioned by fire; and conſequently, that the interior parts of the earth muſt be compoſed of vitrified matter, of which ſand, free-ſtone, granite, and perhaps clay, are fragments, or ſcoriae.
It is therefore extremely probable, that the planets were originally parts of the ſun ſepa⯑rated by a ſtroke which communicated to them a projectile motion; and that their different diſtances proceeded ſolely from the difference of their denſities. To compleat this theory, it on⯑ly remains to account for the diurnal motion of the planets, and the origin of their ſatellites; and this, inſtead of adding freſh difficulties, will tend greatly to confirm my hypotheſis: For ro⯑tation, or what is called diurnal motion, entire⯑ly depends on the obliquity of the ſtroke; an oblique impulſe on the ſurface of a body neceſ⯑ſarily gives it a rotatory motion. If the body which receives the impulſe be homogeneous, the rotatory motion will always be equal and uni⯑form; but it will be unequal, if the body con⯑ſiſt of heterogeneous parts, or of parts different in denſity. Hence we may conclude, that the matter of each planet is homogeneous, becauſe the diurnal motion of each is uniformly per⯑formed in the ſame time; and this circumſtance is an additional proof, that portions of different denſities were originally ſeparated from the ſun.
[81] But the obliquity of the ſtroke might be ſo great as to throw off ſmall quantities of matter from the principal planet, which would neceſ⯑ſarily move in the ſame direction. Theſe parts, by mutual attraction, would reunite, according to their denſities, at different diſtances from the planet, follow its courſe round the ſun, and at the ſame time revolve about the body of the planet, nearly in the plane of its orbit. It is eaſy to perceive that the portions we mean are the ſatellites: Thus the formation, poſition, and motion of the ſatellites correſpond, in the moſt perfect manner, with our theory; for they all move in the ſame direction, and in concentric circles round their principal planets, and nearly in the plane of their orbits. All theſe common effects, depending on an impulſive force, muſt have proceeded from a common cauſe, which was a projectile force communicated to them by the ſame oblique ſtroke. This account of the motion and formation of the ſatellites will be ſtrongly ſupported, if the other circumſtances and phaenomena attending them be duly weigh⯑ed. Thoſe planets that are furniſhed with ſatel⯑lites, move quickeſt round their axes. The re⯑volution of the earth is quicker than that of Mars, in the proportion nearly of 24 to 15; the earth has a ſatellite, and Mars has none; Jupiter; whoſe diurnal motion is 500 or 600 times more rapid than that of the earth, has four ſatellites; and it is extremely probable, that Saturn, who [82] has five ſatellites and a ring, revolves much more quickly than Jupiter.
We may even conjecture, with ſome proba⯑bility, that the plane of the equator of Saturn's ring is nearly the ſame with that of the planet; for, ſuppoſing, according to the preceding theory, the obliquity of the impulſe which put Saturn in motion to have been very great, his diurnal motion would at firſt be in proportion to the exceſs of the centrifugal force above that of gra⯑vity, and, of courſe, a conſiderable quantity of matter would be thrown off from his equatorial regions, and neceſſarily aſſume the figure of a ring, the plane of which would be nearly the ſame with that of his own equator. This quan⯑tity of matter detached from the equatorial re⯑gions of Saturn, muſt have flattened the equator of that planet; which is the reaſon why, not⯑withſtanding the rapidity with which we have ſuppoſed him to revolve round his axis, the di⯑ameters of Saturn are not ſo unequal as thoſe of Jupiter, which differ from each other more than an eleventh part.
Though this theory of the formation of the planets and their ſatellites appears to be extreme⯑ly probable; yet, as every man has his own ſtandard of eſtimating probabilities of this na⯑ture, and as this ſtandard varies according to the different capacities of combining analogies more or leſs remote, I pretend not to convince thoſe who are unwilling to believe. I have offered thoſe [83] ideas to the public, not only becauſe I thought them rational, and calculated to unravel a ſub⯑ject upon which, however important, nothing has hitherto been written; but becauſe the im⯑pulſive motion of the planets gives riſe to num⯑berleſs phaenomena in the univerſe, which ad⯑mit not of an explanation by gravity alone. To thoſe who may be diſpoſed to deny the poſſibi⯑lity of my theory, I would propoſe the follow⯑ing queries:
1. Is it not natural to imagine, that a moving body has received its motion from the impulſe of ſome other body?
2. When ſeveral bodies move in the ſame di⯑rection, is it not exceedingly probable, that they received this direction from a ſingle ſtroke, or, at leaſt, from ſtrokes every way ſimilar?
3. When ſeveral bodies in motion have not only the ſame direction, but are placed in the ſame plane, is it not more natural to think that they received this direction and poſition from one impulſe than from many?
4. Is it not probable, that a body put in mo⯑tion by impulſe, ſhould receive it in an oblique direction; and conſequently that it ſhould be forced to move round its axis with a rapidity proportioned to the obliquity of the ſtroke? If theſe queries be not unreaſonable, the theory of which we have given a ſketch will no longer have the appearance of abſurdity.
[84] Let us now proceed to a more intereſting ob⯑ject; let us examine the figure of the earth, upon which ſo many inquiries and obſervations have been made. As it appears, from the e⯑quality of the earth's diurnal motion, and the uniformity in the inclination of its axis, that it is compoſed of homogeneous parts which mu⯑tually attract each other in proportion to their quantities of matter; if its impulſive motion had been communicated in a direction perpen⯑dicular to its ſurface, it would neceſſarily have aſſumed the figure of a perfect ſphere: But, having been ſtruck obliquely, it moved round its axis at the inſtant it received its figure; and, from the combination of the projectile force and that of attraction, there reſulted a ſpheroid fi⯑gure, more elevated at the equator than at the poles; becauſe the centrifugal force, ariſing from the diurnal rotation of the earth, muſt diminiſh the action of gravity, or that power which makes all the parts tend to the centre. Thus the earth, being compoſed of homogeneous parts, and ha⯑ving been endowed with a rotatory motion, muſt neceſſarily have aſſumed a ſpheroidal figure, the two axes of which differ from each other by a 230th part. To ſhow that this is the real figure of the earth, we need not have re⯑courſe to hypotheſes; it is capable of the clear⯑eſt demonſtration. The laws of gravitation are well known: That bodies attract each other di⯑rectly [85] as their quantities of matter, and inverſe⯑ly as the ſquares of their diſtances, admits not of a doubt. It can as little be doubted, that the total action of any body is compoſed of all the particular actions of its parts.
The parts of bodies are all mutually attracted in the above proportion; and all theſe attractions, when the body has no rotation, neceſſarily pro⯑duce a ſphere, and a ſpheroid, when the body is endowed with a rotatory motion. This ſpheroid is more or leſs flattened at the poles in proportion to the quickneſs of its diurnal motion; and the earth, in conſequence of the celerity of its ro⯑tation, and the mutual attraction of its parts, has aſſumed the figure of a ſpheroid, of which the two axes are to one another as 229 to 230.
Thus the earth, at the time of its formation, from the original conſtitution and homogeneity of its parts, and independent of every hypothe⯑ſis derived from the direction of gravity, took the figure of a ſpheroid; and, from the known laws of mechanics, its equatorial diameter was neceſſarily elevated about ſix leagues and a half more than its poles.
I ſhall dwell the longer on this article, be⯑cauſe there are ſome geometers, who, from a ſyſtem of philoſophy they have adopted, and from a ſuppoſed direction of gravity, ſtill ima⯑gine that the figure of the earth depends upon theory. The firſt thing to be demonſtrated is [86] the mutual attraction of the parts of matter; and the ſecond, the homogeneity of the terreſtri⯑al globe. When theſe two facts are clearly pro⯑ved, there will be no occaſion to have recourſe to any theory derived from the direction of gravity; becauſe the earth's figure, in this caſe, muſt neceſſarily be as Newton determined it; and all the other figures aſſigned to it in conſe⯑quence of vortexes, and other hypotheſes, can have no exiſtence.
It will not be doubted, even by the moſt in⯑credulous, that the planets are retained in their orbits by the power of gravity. The ſatellites of Saturn gravitate towards that planet, thoſe of Jupiter towards Jupiter; the moon gravitates towards the earth; and Saturn, Jupiter, Mars, the Earth, Venus, and Mercury, gravitate to⯑wards the ſun. In the ſame manner, Saturn, Jupiter, and the Earth, gravitate towards their reſpective ſatellites, and the ſun gravitates to⯑wards the whole planets. Gravitation is there⯑fore a general law, by which the whole planetary ſyſtem is mutually affected; for action cannot exiſt without re-action. This mutual attraction of the planets is the law which regulates all their motions; and its exiſtence is demonſtrated by its effects. When Saturn and Jupiter are in con⯑junction, their mutual attraction produces an irregularity in their motion round the ſun. The earth and the moon, alſo, mutually attract each other; But the irregularities in the moon's mo⯑tion [87] proceed principally from the attraction of the ſun; and hence the ſun, the earth, and the moon, mutually act upon each other. Now, the reciprocal attraction of the planets, when the diſtances are equal, is proportioned to their quan⯑tities of matter; and the ſame power of gravi⯑ty, which makes heavy bodies fall to the earth, and which extends as far as the moon, is like⯑wiſe in proportion to the quantity of matter: The total gravity of a planet, therefore, is com⯑poſed of the gravity of all its parts: Hence all the parts of matter, whether in the earth or pla⯑nets, mutually attract each other; and, of courſe, the rotation of the earth round its axis muſt neceſſarily have beſtowed on it the figure of a ſpheroid, the axes of which are are as 229 to 230. But the direction of gravity muſt be perpendicular to the earth's ſurface; and, conſequently, unleſs the general and mutual attraction of the parts of matter be denied, no hypotheſis derived from the direction of gravity can have any ſolid foun⯑dation. But this mutual attraction, as we have ſeen, is demonſtrated by actual obſervation; and the experiments made by pendulums prove its univerſal extenſion. No hypotheſis, there⯑fore, founded on the direction of gravity, can be admitted, without contradicting both reaſon and experience.
Let us now examine whether the parts com⯑poſing the terreſtrial globe be homogeneous. I acknowledge, that, if the globe be ſuppoſed to [88] conſiſt of parts different in denſity, the direction of gravity would be different from that we have aſſigned, and that the earth's figure would vary according to the different ſuppoſitions that might be made concerning the direction of gravity. But, why make ſuppoſitions of this kind? Why, for example, do we ſuppoſe the parts near the center to be more denſe than thoſe more diſtant from it? Are not all the particles which compoſe the globe united by their mutual attraction? Every particle, therefore, is a centre; and there is no reaſon to believe that the parts which ſur⯑round the centre are denſer than thoſe which ſurround any other point. Beſides, if any con⯑ſiderable part of the earth were more denſe than another, the axis of rotation would approach nearer that part, and create an inequality in the diurnal revolution of the globe: It would pro⯑duce an inequality in the apparent motion of the fixed ſtars; they would appear to move more quickly or ſlowly in the zenith or horizon, ac⯑cording as we happened to be ſituated on the heavy or light parts of the earth; and the axis of the globe not paſſing through its centre of gravity, would make a perceptible change in its poſition. But nothing of this kind ever takes place. On the contrary, the diurnal revolution of the earth is equal and uniform. At every point of the earth's ſurface, the ſtars appear to move with the ſame quickneſ and, if there be any rotation in its axis, it is too inconſiderable [89] to attract obſervation. Hence it may be con⯑cluded, that all the parts of the globe are at leaſt nearly homogeneous.
If the earth were hollow, the cruſt of which, for example, exceeded not three leagues in thick⯑neſs, it would give riſe to the following phae⯑nomena. 1. The mountains would bear ſo great a proportion to the total thickneſs of the cruſt, that vaſt irregularities in the earth's mo⯑tion would be occaſioned by the attraction of the moon and of the ſun: When the moon was in the meridian of the more elevated parts, as the Cordeliers, her attraction upon the whole globe would be much greater, than when ſhe was in the meridian of the lower parts. 2. The comparative attraction of the mountains would be greatly increaſed; and the experiments made on Mount Chimboraco in Peru, would have gi⯑ven more degrees in the deviation of the plumb line than they actually gave ſeconds. 3. The weight of bodies would be greater on the tops of mountains than in the plains; and men would find themſelves more weighty, and would walk with more difficulty in high than in low grounds. Theſe obſervations, and many others that might be made, ſhould convince us, that the interior parts of the earth are not hollow, but that they are compoſed of matter of a conſiderable den⯑ſity.
If, on the other hand, the earth, at the depth of two or three leagues, conſiſted of matter [90] much denſer than that we are acquainted with, upon deſcending even into ordinary pits, we ſhould find ourſelves conſiderably heavier; and the motion of pendulums would there be more ac⯑celerated than they actually are when brought down from a hill to a plain. Hence we may preſume, that the interior parts of the earth con⯑ſiſt of matter nearly ſimilar to that on its ſur⯑face. Of this, we will be ſtill further convinced, if we conſider, that the earth, at the time of its original formation, when it aſſumed its preſent ſpheroidal figure, was in a ſtate of fuſion, and, conſequently, that all its parts were homogeneous, and nearly of equal denſity. The matter on the ſurface, though originally the ſame with that of the interior parts, has, in the revolutions of time, undergone many changes from external cauſes; and to theſe are to be aſcribed the pro⯑duction of materials ſo different in their denſi⯑ties. But it ought to be remarked, that the denſeſt bodies, as gold, and other metals, are moſt rarely to be met with; and, conſequently, that the greateſt quantity of materials, at the ſurface, have ſuffered little alteration with re⯑gard to denſity. The moſt common materials, indeed, as ſand and clay, differ ſo little in denſi⯑ty, that we may conjecture, with much proba⯑bility, the internal parts of the earth to conſiſt of a vitrified matter, the denſity of which is nearly equal to that of ſand; and, conſequently, [91] that the whole globe may be conſidered as one homogeneous maſs.
But, it may be ſaid, that, though the earth were compoſed of concentric beds, of different denſities, the equality of its diurnal motion, and the uniform inclination of its axis, would re⯑main equally undiſturbed, as upon the ſuppoſi⯑tion of its conſiſting wholly of homogeneous matter. This I allow; but I demand, at the ſame time, whether there be any reaſon for be⯑lieving, that theſe beds of different denſities really exiſt? Whether this method of ſolving difficulties be not an attempt to adjuſt the works of nature to our own imaginations? And whe⯑ther ſuppoſitions, neither founded on obſervation nor analogy, ought to find admittance into phy⯑ſics?
It is, then, apparent, that the earth received its ſpheroidal figure in conſequence of its diurnal motion, and the mutual attraction of its parts; that this figure neceſſarily reſulted from the globe's being in a liquid ſtate; that, according to the laws of gravity and of a centrifugal force, it could not poſſibly aſſume any other figure; that, at the moment of its formation, the diffe⯑rence between its two diameters was, as at pre⯑ſent, equal to a 230th part; and, of courſe, that all other hypotheſes which make this difference greater or leſs, are mere fictions, and deſerve no attention.
[92] Perhaps it may be objected, that, if this theo⯑ry be well founded, and if the proportion of the axes of the two diameters be as 229 to 230, how came the mathematicians ſent to Lapland and Peru to concur in making it as 174 to 175? Why ſhould ſuch a difference ſubſiſt between practice and theory? And, is it not more rea⯑ſonable to give the preference to actual meaſure⯑ment, eſpecially when executed by the ableſt mathematicians in Europe*, and furniſhed with all the neceſſary apparatus?
To this I reply, that I mean not to combat the obſervations made at the equator, and near the pole; that I doubt not of their exactneſs; and that the earth may actually be elevated a 175th part more at the equator than at the poles. Still, however, I maintain my theory; and I perceive clearly how it may be reconciled to practice. The difference between the two concluſions is about four leagues in the two axes. The equa⯑torial regions are found to have an elevation of two leagues more than they ought to have by the theory. This heighth of two leagues cor⯑reſponds exactly with the greateſt inequalities which have been produced on the ſurface of the globe by the motion of the ſea, and the action of fluids. This requires illuſtration. At the time of the earth's formation, in conſequence of the mutual attraction of its parts, and of its cen⯑trifugal force, it muſt have aſſumed a ſpheroidal [93] figure, with its axes different by a 230th part. This would be the real figure of the earth while it remained in a ſtate of liquifaction. But, af⯑ter cooling for ſome time, the rarified vapours, like thoſe in the tail or atmoſphere of a comet, would condenſe, and fall on the ſurface in the form of air and water; and, when theſe waters began to be agitated by a flux and reflux, ſand, and other bodies, would be gradually tranſported from the poles towards the equatorial parts. This operation, when continued for ſome time, would neceſſarily ſink the poles, and elevate the equator in the ſame proportion. The ſurface of the earth being likewiſe expoſed to the winds, to the action of the air and of the ſun; all theſe cauſes would concur with the tides in furrow⯑ting the earth, in ſcooping out vallies, in eleva⯑ing the mountains, and in producing other ſu⯑perficial irregularities, none of which, perhaps, exceed a league in thickneſs, even at the equa⯑tor. This inequality of two leagues may be ſuppoſed to be the greateſt that can take place on the ſurface; for the higheſt mountains ex⯑ceed not a league in height; and the moſt pro⯑found parts of the ocean, it is probable, are not above a league in depth. Thus my theory per⯑fectly coincides with practice. The earth's e⯑quator could not, at firſt, be elevated more than ſix leagues and a half above the poles; but the changes produced on the ſurface might give it a ſtill greater elevation. Natural hiſtory won⯑derfully [94] ſupports this opinion; for, in the pre⯑ceding diſcourſe, we have proved, that, from the tides and other motions of the waters, have proceeded mountains, and all the other inequa⯑lities on the ſurface of the globe; and that, at great depths, as well as upon the greateſt heights, bones, ſhells, and other relicts of ſea and land animals, have been diſcovered.
From what has been obſerved, it may be con⯑jectured, that, in order to find primitive earth, and ſubſtances which have never been removed from their original ſtations, we muſt dig in countries near the poles, where the bed of unmoved earth will be thinner than in ſouthern climates.
In fine, if the meaſurement by which the fi⯑gure of the earth was determined be ſtrictly ſcrutinized, we ſhall find that it is not altogether free from hypothetical reaſoning: For it pro⯑ceeded on the ſuppoſition that the earth was a regular curve: But, as the earth is liable to con⯑ſiderable and conſtant changes from a thouſand cauſes, it is impoſſible that it could have retained any perfectly regular figure; and hence, agree⯑able to our theory, and the opinion of Newton, the poles might originally be only flattened a 230th part. Beſides, though we had the exact length of a degree at the equator and polar circle, yet, have we not likewiſe the exact length of a degree in France? and the meaſures of M. Picard have never been confirmed. It may be [95] added, that the diminution and increaſe in the motion of the pendulum agree not with the con⯑cluſions drawn from meaſurement; and that, on the contrary, they correſpond very nearly to the theory of Newton. Theſe circumſtances tend farther to convince us, that the poles are not de⯑preſſed above a 230th part; and that, if there be any difference, it can proceed from nothing but the inequalities produced on the ſurface by the waters, and other external cauſes. But theſe inequalities are by no means ſo regular as to juſtify any hypotheſis which ſuppoſes the meri⯑dians to be ellipſes, or any other perfect curves. Hence it appears, that, though many degrees ſhould be ſucceſſively meaſured in different re⯑gions, we cannot, by that alone, aſcertain the exact depreſſion of the poles, nor determine how much it exceeds or falls ſhort of a 230th part.
May we not likewiſe conjecture, that, if the inclination of the earth's axis has been changed, this effect could not be produced but by the changes on the ſurface, ſince all the other parts are homogeneous; that this variation is, of courſe, too ſmall to be perceived by aſtrono⯑mers; and that, if the earth be not diſturbed by a comet, or ſome other external cauſe, its axis will for ever preſerve its preſent and original inclination?
Not to omit any conjecture that ſeems rea⯑ſonable, may we not ſuppoſe, that, as the moun⯑tains, and other inequalities on the ſurface of [96] the earth, have originated from the action of the tides, thoſe which we perceive in the moon have been produced by a ſimilar cauſe? The mountains of the moon are indeed higher than thoſe of the earth; but her tides are likewiſe ſtronger; becauſe the earth, the ſize of which is much larger, produces the tides of the moon with ſuperior force. This effect would be great⯑ly augmented, if the moon, like the earth, had a quick diurnal motion. But, as the moon uni⯑formly preſents the ſame face to the earth, the tides are raiſed only in proportion to the mo⯑tion occaſioned by her librations, which alter⯑nately expoſe to our view a ſmall ſegment of her other hemiſphere. This cauſe, however, muſt produce tides very different from thoſe of our ſeas; and their effects will, of courſe, be much leſs conſiderable, than if the moon had poſſeſſed a diurnal revolution round her axis, equally quick as the rotation of the earth.
I ſhould compoſe a volume equal to that of Burnet or Whiſton, were I to extend the ideas preſented by the above theory; and were I, in imitation of the laſt mentioned author, to clothe them in a geometrical dreſs, I might add conſi⯑derably to their importance. But I have always thought, that hypotheſes, however probable, de⯑ſerve not to be treated ſo pompouſly; it is apt to give them the air of quackery and impoſition.
THIS author begins his theory with a diſ⯑ſertation on the creation of the world. He alledges, that the account given of it by Moſes is not properly underſtood; and that, in inquiries of this kind, men, contenting them⯑ſelves with the moſt evident and ſuperficial views, give too little of their attention to nature, rea⯑ſon, and philoſophy. The common notions, he obſerves, concerning the ſix days work, are falſe; and the deſcription of Moſes is not an exact or philoſophic account of the creation and origin of the univerſe, but only an hiſtorical [98] narrative of the formation of the terreſtrial globe. The earth, in his eſtimation, formerly exiſted in Chaos, and, at the time mentioned by Moſes, it only received a form, ſituation, and conſiſtence, neceſſary for the habitation of mankind. I ſhall not give a detail of Whiſton's proofs, nor enter upon a formal refutation of them; but content myſelf with a ſhort view of his theory, which will ſhow it to be contrary to the ſcrip⯑tures, and, of courſe, that his proofs muſt be falſe. Beſides, he treats this matter more like a polemical divine than a philoſopher.
Leaving theſe falſe principles, he proceeds to ſome ingenious notions, which, though ſingu⯑lar, will not, to thoſe who are influenced by the enthuſiaſm of ſyſtem, appear to be deſtitute of probability. He tells us, that the antient Chaos, from which the earth originated, was the at⯑moſphere of a comet; that the annual motion of the earth began when it received its new form; but that its diurnal motion commenced not till the fall of Adam; that the Ecliptic cut the tropic of Cancer in a point preciſely oppo⯑ſite to Paradiſe, which was ſituated on the north⯑weſt frontier of Aſſyria; that, before the de⯑luge, the year began at the autumnal equinox, and that the orbits of the earth and planets were then perfect circles; that the deluge commen⯑ced on the 18th of November, in the year of the Julian period 2365, or 2349 before Chriſt; that, previous to the deluge, the ſolar and lunar [99] year were the ſame, and conſiſted exactly of 360 days; that a comet, deſcending in the plane of the ecliptic to its perihelion, on the very day that the deluge began, made a near approach to the earth; that there is a great heat in the bowels of the earth, which is conſtantly expanding from the centre to the circumference; that the figure of the earth reſembles an egg; that the mountains are the lighteſt parts of the globe, &c. He then attributes to the deluge all the changes the earth has undergone, blindly adopts Woodward's theory, uſes indiſcriminately all that author's remarks on the preſent ſtate of the earth; but aſſumes more the air of an original, when he treats of its future condition. The earth, ſays Mr Whiſton, will be conſumed by ſire; and its deſtruction will be preceded by earthquakes, thunder, and hideous meteors; the ſun and moon will aſſume a dreadful aſpect; the heavens will ſeem to fall; and the whole earth will be in flames. But, after the fire ſhall have devoured every impurity of this globe, and vi⯑trified and rendered it tranſparent as the pureſt cryſtal, the ſaints and ſpirits of the bleſſed ſhall take poſſeſſion of it, and there remain till the general judgment.
This hypotheſis appears, at firſt view, to be extravagant and fantaſtical. But the author has managed his ideas with ſuch dexterity, and pla⯑ced them in ſo ſtrong a light, that they no long⯑er have the air of abſolute chimeras. He has [100] adorned his ſubject with much ſcience and in⯑genuity: And it is aſtoniſhing, that, from ſuch a medley of ſtrange notions, he ſhould have been able to compoſe a ſyſtem ſo plauſible. But it is not to the vulgar that it has this brilliant appearance; the learned are more eaſily de⯑ceived by the glare of erudition, and the force of new ideas. Mr Whiſton was a celebrated a⯑ſtronomer. Accuſtomed to contemplate the hea⯑vens, to meaſure the motions of the ſtars, and to conſider the great phaenomena of nature, he could never imagine, that this grain of ſand, which we inhabit, occupied more the attention of its Creator than the univerſe, which contains, in the vaſt regions of ſpace, millions of other ſuns and other worlds. He alledges, that Moſes has not given us the hiſtory of the firſt creation of this globe, but only a detail of thoſe circum⯑ſtances which attended its receiving a form fit for the habitation of men, when the Almighty transformed it from the ſtate of a comet to that of a planet. Comets, owing to the excentricity of their orbits, are ſubject to dreadful viciſſi⯑tudes: Sometimes, like that of 1680, they are a thouſand times hotter than melted iron, and ſometimes a thouſand times more cold than ice: They cannot, therefore, furniſh habitation to any creatures of which we can form a concep⯑tion; or rather, they are altogether uninhabi⯑table.
[101] The planets, on the contrary, are tranquil bo⯑dies; their diſtances from the ſun vary but little; and their temperature continues ſo nearly the ſame, that it permits plants and animals to grow and to multiply.
In the beginning, ſays Mr Whiſton, God created the univerſe; but the earth was then an uninhabitable comet, and ſubject to ſuch alter⯑nate extremes of cold and heat, that its matter, being ſometimes liquified and ſometimes frozen, was in the form of a chaos, or an abyſs, ſur⯑rounded with utter darkneſs: And darkneſs co⯑vered the face of the deep. This chaos was the atmoſphere of the comet, a body compoſed of heterogeneous materials, having its centre oc⯑cupied with a globular, ſolid, hot nucleus of about 2000 leagues in diameter, round which was an extenſive maſs of a thick fluid, mixed with heterogeneous and undigeſted materials, like the chaos of the antients, rudis et indigeſ⯑taque moles. This great atmoſphere contained few dry, ſolid, or earthy particles, and ſtill leſs of water or air; but it was amply filled with thick and heavy fluids, mixed, agitated, and jumbled together in the utmoſt confuſion. Such was the condition of the earth when ſix days old: But, next day, that is, on the firſt day of the creation, when the excentric orbit of the comet was changed into an ellipſe, nearly cir⯑cular, every thing aſſumed its proper place; the different materials arranged themſelves accor⯑ding [102] to their ſpecific gravities; the heavy fluids ſunk down, and left to the earthy, watery, and aerial ſubſtances, the ſuperior regions. Theſe alſo deſcended in the order of their gravities; firſt the earth, then the water, and, laſtly, the air. In this manner, the immenſe volume of chaos was reduced to a moderate ſphere, the center of which is a ſolid body that ſtill retains the heat it received from the ſun, when former⯑ly the nucleus of a comet. This heat may eaſily laſt 6000 years, ſince the comet 1680 would re⯑quire 50,000 before it cooled. Round the ſo⯑lid and burning nucleus, at the center of the earth, is placed the heavy fluid which deſcended firſt, and formed the great abyſs, upon which the earth floats like a cork on quick-ſilver. But, as the earthy parts were originally mixed with a great body of water, they, in deſcending, drove before them a part of this water, which was conſined there when the earth conſolidated, and formed a ſtratum concentric with the heavy fluid that ſurrounds the nucleus. Thus, the great abyſs is compoſed of two concentric circles, the interior being a heavy fluid, and the ſupe⯑rior water, upon which laſt the earth is imme⯑diately founded. From this admirable arrange⯑ment, produced by the atmoſphere of a comet, are to be deduced the theory of the earth, and an explication of all its phaenomena.
After the atmoſphere of the comet had been freed from the ſolid and earthy particles, a pure [103] air only remained, through which the rays of the ſun inſtantly penetrated, and produced light: Let there be light; and there was light. The vaſt columns or beds of which the earth is com⯑poſed, being formed with ſo much precipitation, is the reaſon why they differ ſo much in denſity; the heavier ſunk deeper into the abyſs than the lighter, and, of courſe, gave riſe to mountains and valleys: Theſe inequalities, before the de⯑luge, were differently ſituated from what they are at preſent. Inſtead of that vaſt valley which contains the ocean, many ſmall caverns were diſperſed over the globe, each of which contain⯑ed a part of the waters. The mountains were then at greater diſtances, and formed not large chains. But the earth was a thouſand times more fertile, and contained a thouſand times more inhabitants; and the life of man, and of the other animals, was ten times longer, All theſe effects were produced by the ſuperior heat of the central fire, which gave birth to a great⯑er number of plants and animals, and, at the ſame time, beſtowed on them a degree of vigour that enabled them to exiſt long, and to multi⯑ply abundantly. But this heat had a miſerable effect upon the diſpoſitions of men and other animals: It augmented the paſſions, robbed man of his innocence, and diminiſhed the ſagacity of the brute creation. All creatures, excepting the fiſhes, who inhabited a colder element, felt the influence of the central heat, became vicious, [104] and merited death. This univerſal death was accordingly inflicted, on Wedneſday the 28th day of November, by a dreadful deluge, which laſted 40 days and 40 nights, and was occa⯑ſined by the tail of a comet meeting with the earth, in returning from its perihelion.
The tail of a comet is the lighteſt part of its atmoſphere. It is a tranſparent and ſubtile va⯑pour raiſed by the heat of the ſun from the bo⯑dy of the comet. This vapour, which is com⯑poſed of aerial and watery particles extremely rarified, follows the comet in its deſcent to its perihelion, and goes before the comet in its aſcent, its ſituation being always oppoſite to the ſun, as if it had an affection for the ſhade, and wiſhed to avoid the ſcorching rays of the ſun. This column of a vapour is often of an im⯑menſe extent; and its length always increaſes in proportion as the comet approaches nearer the ſun. Now, as many comets deſcend below the annual orbit of the earth, it is not ſurpriſing that the earth ſhould ſometimes be involved in this vapour. This dreadful event happened at the time of the deluge. The tail of a comet, in two hours, will diſcharge a quantity of water equal to that contained in the whole ocean. In fine, this tail is what Moſes calls the cataracts of heaven: And the cataracts of heaven were opened. The globe of the earth, when it meets with a comet's tail, muſt neceſſarily, in its paſ⯑ſage through this body of vapour, appropriate [105] part of its materials. Every thing that comes within the ſphere of the earth's attraction muſt fall upon it, and muſt fall in the form of va⯑pour, ſince the tail itſelf principally conſiſts of that element. In this manner, rain may come from the heavens in ſuch abundance, as to pro⯑duce an univerſal deluge, and to ſurmount the tops of the higheſt mountains.
Our author, however, unwilling to go beyond the letter of the ſacred writings, does not aſcribe the deluge to this rain alone, which he has cho⯑ſen to bring from ſo great a diſtance. He takes advantage of water wherever he can find it: The great abyſs, as we have ſeen, contains a conſiderable quantity. The earth, in its ap⯑proach towards the comet, would feel the force of its attraction; the waters in the great abyſs would be ſo agitated with a motion ſimilar to that of the tides, as would neceſſarily break the ſhell or cruſt in many places, and make the water ruſh out upon the ſurface: And the fountains of the abyſs were opened.
But how, it may be aſked, was this vaſt col⯑lection of water, ſo liberally furniſhed by the great abyſs, and by the comet's tail, afterwards diſpoſed of? Our author is not embarraſſed by this circumſtance. As ſoon as the earth eſcaped from the comet, the flux and reflux of the great abyſs neceſſarily ceaſed. From that moment, the waters on the ſurface ruſhed down with vio⯑lence by the ſame channels out of which they [106] had iſſued. The great abyſs ſwallowed up not only its own water, but all that had been depo⯑ſited by the comet, which it was ſufficiently e⯑nabled to contain; becauſe, during its agitation, and when it broke the cruſt, it had greatly en⯑larged its dimenſions, by puſhing the earth far⯑ther from it on all ſides. It was at this time likewiſe, that the earth, which was formerly a ſphere, aſſumed its elliptical figure. This effect was produced by the centrifugal force occaſion⯑ed by the diurnal motion of the earth, and by the attraction of the comet; for the earth, when paſſing through the tail of the comet, was ſo ſi⯑tuated, that its equatorial parts were neareſt that ſtar; and, of courſe, the power of the comet's attraction, concurring with the earth's centrifu⯑gal force, elevated the equatorial regions with the greater facility, becauſe the cruſt was broken in an infinite number of places, and becauſe the flux and reflux of the abyſs puſhed more vio⯑lently againſt the equator than any where elſe.
This is the hiſtory Mr Whiſton gives of the creation, of the cauſes of the univerſal deluge, of the longevity of the Antedeluvians, and of the figure of the earth. All theſe difficult ſub⯑jects ſeem to have given our author very little trouble. But he appears to be greatly puzzled about Noah's ark. In that dreadful confuſion produced by the conjunction of the tail of a comet, and by the waters of the great abyſs, and in that horrible period, when not only [107] the elements of this globe were confounded, but when the heavens concurred with the bowels of the earth in producing new ele⯑ments to increaſe the chaos, how is it to be ima⯑gined that the ark could float tranquilly, with its numerous and valuable cargo, upon the ſur⯑face of the waves? Here our author ſtruggles hard, in order to account for the preſervation of the ark. But, as his reaſoning, upon this ſub⯑ject, appears to be inconcluſive, ill-imagined, and heterodox, I ſhall only obſerve how hard it is for a man, who had explained objects ſo great and ſurpriſing, without having recourſe to a ſupernatural power, to be ſtopped in his career by a trifling circumſtance. But he chuſes to riſk drowning himſelf along with the ark, rather than to aſcribe the preſervation of this precious veſſel to the interpoſition of the Al⯑mighty!
I ſhall only make a ſingle remark upon this ſyſtem, of which I have given a faithful abridge⯑ment. Whenever men are ſo preſumptuous as to attempt a phyſical explanation of theological truths; whenever they allow themſelves to in⯑terpret the ſacred text by views purely human; whenever they reaſon concerning the will of the Deity, and the execution of his decrees; they muſt neceſſarily involve themſelves in obſcurity, and tumble into a chaos of confuſion, like the author of this whimſical ſyſtem, which, notwith⯑ſtanding [108] all its abſurdities, has been received with great applauſe. Mr Whiſton neither doubt⯑ed of the truth of the deluge, nor of the au⯑thenticity of the ſacred writings. But, as phy⯑ſics and aſtronomy occupied his principal at⯑tention, he miſtook paſſages of holy writ for phyſical facts, and for reſults of aſtronomical obſervation; and ſo ſtrangely jumbled divinity with human ſcience, that he has given birth to the moſt extraordinary ſyſtem that perhaps ever did or ever will appear.
MR Burnet is the firſt author who diſco⯑vered enlarged views of the preſent ſub⯑ject, and who treated it in a ſyſtematic manner. He was a man of genius and of taſte: His work acquired great reputation, and was, of courſe, criticiſed by many of the learned, and, among others, by Mr Keill, who, ſcrutinizing the ſub⯑ject as a geometer, demonſtrated the errors of Burnet's theory in a treatiſe entitled, An exami⯑nation of the Theory of the earth. Mr Keill likewiſe refuted the ſyſtem of Whiſton; but he treated the latter in a manner very different from the former. He even appears, in many particulars, to adopt the opinions of Whiſton; and conſiders the notion, that the deluge was [110] occaſioned by the tail of a comet, as exceeding⯑ly probable. But, to return to Burnet: His book is equally written; he knows how to paint the grandeſt images and the moſt magnificent ſcenes. His plan is elevated; but, being defec⯑tive in proper materials, he often fails in the execution. His reaſonings and his proofs are feeble; but the boldneſs with which he writes makes the reader loſe ſight of all his imper⯑fections.
He begins with alledging, that the earth, be⯑fore the deluge, was very different from what it is now. It was at firſt, ſays he, a fluid maſs, compoſed of matters of every ſpecies, and of all kinds of figures, the heavieſt of which deſcend⯑ed to the centre, and there formed a hard and ſolid body. The waters took their ſtation round this body; and all lighter fluids roſe above the water. Thus, between the coat of air, and that of water, was interpoſed a coat of oily matter. But, as the air was then full of impurities, and contained great quantities of earthy particles, theſe gradually ſubſided upon the coat or ſtra⯑tum of oil, and formed a cruſt compoſed of earth and oil: This cruſt was the firſt habitable part of the earth, and the firſt abode of man and other animals. This land was light, fat, and adapted to foſter the tenderneſs of the ori⯑ginal germs. The ſurface of the earth was level and uniform, without mountains, ſeas, or other inequalities. But it remained in this ſtare about [111] ſixteen centuries only; for the heat of the ſun gradually drying the cruſt, produced, at firſt, only ſuperficial fiſſures or cracks; but, in pro⯑ceſs of time, theſe fiſſures penetrated deeper, and increaſed ſo much in their dimenſions, that, at laſt, they entirely perforated the cruſt. In an inſtant, the whole earth ſpilt in pieces, and fell into the great abyſs of waters which it formerly ſurrounded. This great event was the univer⯑ſal deluge.
But all theſe maſſes of earth, in falling into the abyſs, carried along with them vaſt quanti⯑ties of air, and they daſhed againſt each other, and accumulated and divided ſo irregularly, that great cavities filled with air were left between them. The waters gradually opened paſſages into theſe cavities, and, in proportion as the ca⯑vities were filled with the water, the ſurface of the earth began to diſcover itſelf in the moſt e⯑levated places; and, at laſt, the waters appeared no where but in thoſe extenſive valleys which contain the ocean. Thus our ocean is a part of the antient abyſs; the reſt of it remains in the internal cavities, with which the ſea has ſtill a communication. Iſlands and ſea-rocks are the ſmall fragments, and continents are the large maſſes of the antient cruſt. As both the rupture and fall of this cruſt were effected in a ſudden and confuſed manner, it is not ſurpriſing that the ſurface of the preſent earth ſhould be full [112] of mountains, gulfs, plains, and irregularities of every kind.
This ſpecimen is ſufficient to give an idea of Burnet's ſyſtem. It is an elegant romance, a book which may be read for amuſement, but which cannot convey any inſtruction. The au⯑thor was ignorant of the chief phaenomena of the earth, and a man of no obſervation. He has drawn every thing from imagination, which often acts againſt both truth and reaſon.
OF this author, it may be ſaid, that he want⯑ed to build an immenſe edifice upon a foundation leſs firm than ſand, and to conſtruct a world with duſt; for he aſſerts, that the earth, at the time of the deluge, ſuffered a total diſſo⯑lution. In peruſing his book, the firſt idea that preſents itſelf is, that this diſſolution was effected by the waters of the great abyſs. He alledges, that, at the command of God, the abyſs ſudden⯑ly opened, and diffuſed ſuch an enormous quan⯑tity of water on the ſurface, as was ſufficient to cover the tops of the higheſt mountains; and [114] that God ſuſpended the law of coheſion, which inſtantly reduced every ſolid ſubſtance into a powder, &c. He did not conſider, that, by theſe ſuppoſitions, he added to the miracle of the univerſal deluge many other miracles, or, at leaſt, phyſical impoſſibilities, which accord neither with the ſcriptures, nor with the prin⯑ciples of mathematics and of natural philoſophy. But, as this author has the merit of collecting many important obſervations, and, as he knew better than any former writer the materials of which the globe is compoſed, his ſyſtem, though ill conceived, and worſe arranged, by the luſtre of a few ſtriking facts, has ſeduced many weak men into a belief of his general concluſions.
We ſhall now give a ſhort view of his theo⯑ry, by which we will be enabled to do juſtice to the [...] of the author, and put the reader in a condition of judging of the futility of his ſyſ⯑tem, and of the falſhood of ſome of his remarks. Mr Woodward informs us, that he recogniſed with his own eyes all the materials of which the earth in England is compoſed, from the ſur⯑face to the greateſt depths that had been dug; that they were all diſpoſed in beds, or ſtrata; and that, in many of theſe beds, there are ſhells and other productions of the ſea. He then adds, that he was aſſured by his friends and cor⯑reſpondents, that, in all the other countries of the world, the earth was compoſed of the ſame ma⯑terials; and that ſhells are found, not only in the [115] plains, and in ſome particular parts, but on the higheſt mountains, in the deepeſt pits, and in an infinite number of different places. He obſerved, that the beds were all horizontal, and placed over each other, like matters tranſported by the waters, and depoſited in the form of ſediment. Theſe general remarks, which are founded in truth, are followed with ſome particular obſer⯑vations, by which he demonſtrates, that the foſ⯑ſil ſhells incorporated with the ſtrata are real ſea-ſhells, and not peculiar minerals, luſus natu⯑rae, &c.
To theſe obſervations, though partly made before him, he has added others of a more ſuſ⯑picious nature. He aſſerts, that the materials of the different ſtrata are arranged according to their ſpecific gravities. This aſſertion is not conſiſtent with truth. We every day ſee ſolid rocks placed above clay, ſand, pit-coal, bitumen, which have unqueſtionably a greater ſpecific gra⯑vity than the latter materials. If, indeed, it were uniformly found, through the whole earth, that the upper ſtratum was bitumen, followed ſucceſſively by ſtrata of chalk, marle, clay, ſand, ſtone, marble, and metals, it would, in that caſe, be probable that all thoſe materials had been precipitated at once: And this our author affirms with confidence, though the moſt ſuperficial ob⯑ſerver needs only his eyes to convince him, that heavy ſtrata are often found above light ones; and, conſequently, that theſe ſediments could not be depoſited at the ſame time, but muſt have [116] been tranſported and dropped by the ocean at ſucceſſive periods. As this is the foundation of Woodward's ſyſtem, and is manifeſtly falſe, we ſhall follow him no farther than to ſhow how an erroneous principle produces falſe rela⯑tions, and bad concluſions.
All the ſtrata that compoſe the earth, ſays our author, from the tops of the higheſt mountains to the deepeſt mines, are placed according to their reſpective ſpecific gravities. Hence, he con⯑cludes, the whole muſt have been in a ſtate of diſſolution, and precipitated at the ſame time. But at what time, in what menſtruum, was it diſſolved? In the water, ſays Mr Wood⯑ward, and at the time of the deluge. But there is not water enough on the globe to produce this effect; for there is more land than water, and the bottom of the ſea itſelf is earth. Very well, he replies; but there is enough of water in the central parts of the earth; and nothing more was wanting than to beſtow on it the power of diſſolving every terreſtrial ſubſtance, except⯑ing ſea-ſhells; to find a proper method of ma⯑king the waters return to the abyſs; and to make all this correſpond with the hiſtory of the deluge. Behold a ſyſtem, of which the author could not prevail on himſelf to form a doubt; for, when it was objected to him, that water could not diſſolve marble, rocks, and metals, e⯑ſpecially in 40 days, the time of the waters re⯑maining on the earth; he replied ſimply, that the event, however, did happen. When it was [117] demanded of him, how the waters of the abyſs could diſſolve the whole earth, and yet preſerve the ſhells? He anſwered, that he never proved that this water was a diſſolvent; but that, from facts, it was clear that the earth had been diſ⯑ſolved, and that the ſhells were preſerved. Laſt⯑ly, When it was demonſtrated to him, that his ſyſtem was uſeleſs, as it was neither ſupported by reaſon nor by facts; he ſaid, we had only to ſuppoſe, that, at the time of the deluge, the laws of gravity and of coheſion were ſuddenly ſtop⯑ped, and, upon this ſuppoſition, the diſſolution of the antient world admitted of an eaſy expla⯑nation. But, it was obſerved to him, if the force of coheſion was ſuſpended, Why were not the ſhells diſſolved along with the reſt? Here he gave a harangue on the organization of ſhells and of animal bones, tending to prove that their texture was fibrous, and different from that of minerals; that their coheſion was likewiſe dif⯑ferent; and that, after all, we have only to ſup⯑poſe that the powers of gravity and of coheſion did not entirely ceaſe, but that they were dimi⯑niſhed to ſuch a degree, as enabled them to diſ⯑ſolve the parts of minerals, but not thoſe of ani⯑mals. I ſhall conclude with remarking, that our author's philoſophy was not equal to his ge⯑nius for obſervation; it is therefore unneceſſary to give a formal refutation of abſurd notions, e⯑ſpecially when they proceed upon conjectures that are contrary both to the laws of probability and of mechanics.
THE three hypotheſes juſt mentioned have many things in common: They all agree in this point, that, at the time of the deluge, both the external and internal form of the earth was changed: But none of theſe theoriſts con⯑ſidered, that the earth, before the deluge, was inhabited by the ſame ſpecies of men and ani⯑mals; and, conſequently, that it muſt have been nearly the ſame, both in figure and ſtructure, as it is at preſent. We are informed by the ſacred writings, that, before the deluge, there were ri⯑vers, ſeas, mountains, and foreſts; that moſt of theſe mountains and rivers remained nearly in their former ſituation; the Tigris and Euphrates, [119] for example, ran through Paradiſe; that the Ar⯑menian mountain on which the ark reſted was, at the deluge, one of the higheſt mountains of the earth, as it is at this day; and that the ſame plants and the ſame animals which inhabited the earth before the deluge, continue ſtill to ex⯑iſt; for we are told of the ſerpent, of the crow, and of the pigeon that carried the olive branch into the ark. Tournefort indeed alledges, that there are no olives within 400 leagues of Mount Araret, and affects to be witty on this head. It is, however, indiſputable, that there were olives in the neighbourhood of this mountain at the time of the deluge; for Moſes aſſures us of the fact in the moſt expreſs manner. Beſides, it is not ſurpriſing, that, in the courſe of 4000 years, the olives ſhould be extirpated in theſe provin⯑ces, and multiplied in others. It is, therefore, contrary both to ſcripture and reaſon, that theſe authors have ſuppoſed the earth, before the de⯑luge, to have been totally different from what it is now; and this oppoſition between their hy⯑potheſes and the ſacred writings, as well as ſound philoſophy, is ſufficient to diſcredit their ſyſtems, although they ſhould correſpond with ſome phae⯑nomena*. Burnet, who wrote firſt, gives nei⯑ther facts nor obſervations in ſupport of his ſyſtem. Woodward's book is only a ſhort eſ⯑ſay, in which he promiſes much more than he was able to perform; it is only a project, with⯑out any degree of execution. He makes uſe of [120] two general remarks, 1. That the earth is every where compoſed of materials which had for⯑merly been in a ſtate of fluidity, and which had been depoſited by the waters in horizontal beds. 2. That, in the bowels of many parts of the earth, there are an infinite number of ſea-bodies. To account for theſe facts, he was recourſe to the univerſal deluge; or rather, he appears to employ theſe as proofs of the deluge. But, like Burnet, he falls into evident contradictions; for it is abſurd to ſuppoſe, with theſe authors, that, before the deluge, there were no mountains, ſince we are expreſsly told, that the waters roſe 15 cubits above the tops of the higheſt moun⯑tains. On the other hand, it is not ſaid, that the waters deſtroyed or diſſolved the mountains. In place of this extraordinary diſſolution, the mountains remained firm in their original ſi⯑tuations, and the ark reſted upon the one which was firſt deſerted by the waters. Beſides, it is impoſſible to imagine, that, during the ſhort time the deluge continued, the waters could diſ⯑ſolve the mountains, and the whole fabric of the earth. Is it not abſurd to ſuppoſe, that, in the ſpace of forty days, the hardeſt rocks and mine⯑rals were diſſolved by ſimple water? Is it not a manifeſt contradiction to admit this total diſ⯑ſolution, and yet to maintain that ſhells, bones, and other productions of the ſea, were able to reſiſt a menſtruum, to which the moſt ſolid ma⯑terials had yielded? Upon the whole, I cannot [121] heſitate in pronouncing, that Woodward, though furniſhed with excellent facts and obſervations, has produced but a weak and inconſiſtent theo⯑ry.
Whiſton, who wrote laſt, has greatly im⯑proved upon the other two; and, though he has given looſe reins to his imagination, it can⯑not be ſaid that he falls into contradiction. He advances many things that are incredible; but they are neither abſolutely nor apparently im⯑poſſible. As we are ignorant of what materials the centre of the earth is compoſed, he thinks himſelf entitled to ſuppoſe it a ſolid nucleus, ſurrounded with a ring of heavy fluid matter, and then follows a ring of water, upon which the external cruſt is ſupported. In this ring of water, the different parts of the cruſt ſunk more or leſs in proportion to their gravities, and gave riſe to mountains and inequalities on the ſurface of the earth. But our aſtronomer here commits a blunder in mechanics. He conſidered not, that the earth, on this ſuppoſition, muſt have formed one uniform arch; and, conſequently, that it could not be ſupported by the water, and far leſs could any part of this arch ſink deeper than another. If this be excepted, I doubt whe⯑ther he has fallen into any other phyſical blunder: He has, however, committed many errors both in metaphyſics and theology. In fine, it cannot be denied abſolutely, that the earth, in meeting with the tail of a comet, would be deluged, e⯑ſpecially [122] if it be allowed to the author, that the tails of comets contain watery vapours. Neither is it abſolutely impoſſible, that the tail of a co⯑met, in returning from its perihelion, ſhould burn the earth, if we ſuppoſe, with Mr Whiſton, that the comet paſſed very near the ſun's body. The ſame obſervations may be made upon the reſt of his ſyſtem. But, though his notions be not abſolutely impoſſible, when taken ſeparate⯑ly, they are ſo exceedingly improbable, that the whole aſſemblage may be regarded as exceeding the bounds of human credulity.
Theſe three are not the only books that have been written upon the theory of the earth. In 1729, M. Bourguet publiſhed, along with his Philoſophical Letters on the formation of Salts, &c. a memoir, in which he gives a ſpecimen of a ſyſtem which he had projected; but the execu⯑tion of it was prevented by the death of the au⯑thor. It muſt be acknowledged, that no man was more induſtrious and acute in making ob⯑ſervations, and in collecting facts. To him we are indebted for remarking the correſpondence between the angles of mountains, which is the chief key to the theory of the earth. He ar⯑ranges the materials he had collected in the beſt order. But, with all theſe advantages, it is pro⯑bable, that he would not have ſucceeded in gi⯑ving a phyſical hiſtory of the changes that have happened in the earth; and he appears not to have diſcovered the cauſes of thoſe effects which [123] he relates. To be convinced of this, we have only to take a view of the propoſitions he de⯑duces from thoſe phaenomena which behoved to be the foundation of his theory. He ſays, that the earth was formed at once, and not ſuc⯑ceſſively; that its figure and diſpoſition demon⯑ſtrate that it was formerly in a fluid ſtate; that the preſent condition of the earth is very differ⯑ent from what it was ſome ages after its firſt formation; that the matter of the globe was originally more ſoft than after its ſurface was changed; that the condenſation of its ſolid parts diminiſhed gradually with its velocity; ſo that, after a certain number of revolutions round its own axis, and round the ſun, its original ſtruc⯑ture was ſuddenly diſſolved; that this happened at the vernal equinox; that the ſea-ſhells inſi⯑nuated themſelves into the diſſolved matters; that the earth, after this diſſolution, aſſumed its preſent form; and that, as ſoon as the fire or heat operated upon it, its conſumption gradually began, and, at ſome future period, it will be blown up with a dreadful exploſion, accompa⯑nied with a general conflagration, which will augment the atmoſphere, and diminiſh the dia⯑meter of the globe; and then the earth, in place of ſtrata of ſand or clay, will conſiſt only of beds of calcined materials, and mountains com⯑poſed of amalgams of different metals.
This is a ſufficient view of the ſyſtem which M. Bourguet deſigned to compoſe. To gueſs at [124] the paſt, and to predict the future, nearly in the ſame manner as others have gueſſed and predic⯑ted, requires but a ſmall effort of genius. This author had more erudition than ſound and ge⯑neral ideas. He appears not to have had the capacity of forming enlarged views, or of com⯑prehending the chain of cauſes and effects.
In the Leipſic Tranſactions, the celebrated Leibnitz publiſhed a ſketch of an oppoſite ſy⯑ſtem, under the title of Protogaea. The earth, according to Bourguet and others, was to be conſumed by fire. But Leibnitz maintains, that it originated from fire, and that it has under⯑gone innumerable changes and revolutions. At the time that Moſes tells us the light was divi⯑ded from the darkneſs, the greateſt part of the earth was in flames. The planets, as well as the earth, were originally fixed and luminous ſtars. After burning for many ages, he alledges, that they were extinguiſhed from a deficiency of combuſtible matter, and that they became o⯑paque bodies. The fire, by melting the matter, produced a vitrified cruſt; and the baſis of all terreſtrial bodies is glaſs, of which ſand and gra⯑vel are only the fragments. The other ſpecies of earth reſulted from a mixture of ſand with water and fixed ſalts; and, when the cruſt had cooled, the moiſt particles, which had been ele⯑vated in the form of vapour, fell down, and formed the ocean. Theſe waters at firſt cover⯑ed the whole ſurface, and even overtopped the [125] higheſt mountains. In the eſtimation of this author, the ſhells, and other ſpoils of the ocean, which every where abound, are indelible proofs that the earth was formerly covered with the ſea; and the great quantity of fixed ſalts, of ſand, and of other melted and calcined matters ſhut up in the bowels of the earth, demonſtrate, that the conflagration had been general, and that it had preceded the exiſtence of the ocean. Theſe ideas, though deſtitute of evidence, are elevated, and bear conſpicuous marks of inge⯑nuity. The thoughts have a connection, the hy⯑potheſes are not impoſſible, and the conſequen⯑ces that might be drawn from them are not con⯑tradictory. But the great defect of this theory is, that it applies not to the preſent ſtate of the earth. It only explains what paſſed in ages ſo remote, that few veſtiges remain; a man may, therefore, affirm what he pleaſes, and what he ſays will be accompanied with more or leſs pro⯑bability, in proportion to the extent of his ta⯑lents. To maintain, with Whiſton, that the earth was originally a comet, or with Leibnitz, that it was a fun, is to aſſert what is equally poſſible or impoſſible; it would, therefore, be ridiculous to inveſtigate either by the laws of probability. The inſtantaneouſneſs of the cre⯑ation deſtroys the notion of the globe's being covered with the ocean, and of that being the reaſon why ſea-ſhells are ſo much diffuſed through different parts of the earth; for, if that [126] had been the caſe, it muſt of neceſſity be allow⯑ed, that ſhells, and other productions of the o⯑cean, which are ſtill found in the bowels of the earth, were created long prior to man, and other land-animals. Now, independent of ſcripture-authority, is it not reaſonable to think that the origin of all kinds of animals and vegetables is equally antient?
M. Scheutzer, in a diſſertation addreſſed to the Academy of Sciences in 1708, attributes, like Woodward, the change, or rather new cre⯑ation of the globe, to the deluge. To account for the formation of mountains, he tells us, that God, when he ordered the waters to return to their ſubterraneous abodes, broke, with his Al⯑mighty hand, many of the horizontal ſtrata, and elevated them above the ſurface of the earth, which was originally level. The whole diſſer⯑tation was compoſed with a view to ſupport this ridiculous opinion. As it was neceſſary that theſe eminences ſhould be of a ſolid conſiſtence, Mr Scheutzer remarks, that God only raiſed them from places which abounded in ſtones. Hence, ſays he, thoſe countries, like Switzerland, which are very ſtony, are likewiſe mountainous; and thoſe, like Flanders, Holland, Hungry, and Po⯑land, which are moſtly compoſed of ſand and clay to great depths, have few or no moun⯑tains*.
[127] This author, like Woodward, blends phyſics and theology; and, though he has made ſome good obſervations, the ſyſtematic part of his work is weaker and more puerile than that of any of his predeceſſors. He has even deſcended to declamation, and abſurd pleaſantries. The reader, if he deſires to ſee them, may con⯑ſult his Piſcium Quaerelae, &c. not to mention his Phyſica Sacra, in ſeveral volumes in folio, a weak performance, fitter for the amuſement of children, than the inſtruction of men.
Steno, and ſome others, have attributed the origin of mountains, and other inequalities, up⯑on the ſurface of the earth, to particular inun⯑dations, earthquakes, &c. But the effects of theſe ſecondary cauſes could produce nothing but ſlight changes. Theſe cauſes may co-ope⯑rate with the firſt cauſe, namely, the tides, and the motion of the ſea from eaſt to weſt. Be⯑ſides, Steno has given no theory, nor even any general facts, upon this ſubject*.
Ray alledges, that all mountains have been produced by earthquakes, and has written a treatiſe to prove it. When we come to the ar⯑ticle of volcano's, we ſhall examine the foun⯑dation of this opinion.
We cannot omit obſerving here, that Burnet, Whiſton, Woodward, and moſt other authors, have fallen into an error which deſerves to be rectified. They uniformly regard the deluge as [128] an effect within the compaſs of natural cauſes, although the ſcripture repreſents it as an imme⯑diate operation of the Deity. It is beyond the power of any natural cauſe to produce on the ſurface of the earth a quantity of water ſufficient to cover the higheſt mountains: And, although a cauſe could be imagined adequate to this effect, it would ſtill be impoſſible to find another cauſe capable of making the waters diſappear. Grant⯑ing that Whiſton's waters proceeded from the tail of a comet, we deny that any of them could iſſue from the abyſs, or that the whole could re⯑turn into it; for the abyſs, according to him, was ſo environed, and preſſed on all ſides by the ter⯑reſtrial cruſt, that it was impoſſible the comet's at⯑traction could produce the leaſt motion in the fluids it contained, far leſs any motion reſem⯑bling the tides: Hence, not a ſingle drop could either proceed from, or enter into the great abyſs. Unleſs, therefore, it be ſuppoſed, that the waters which fell from the comet were an⯑nihilated by a miracle, they would for ever have remained on the ſurface, and covered the tops of the higheſt mountains. The impoſſibility of explaining any effect by natural cauſes, is the moſt eſſential character of a miracle. Our au⯑thors have made ſeveral vain efforts to account for the deluge. Their errors in phyſics, and in the ſecondary cauſes they employ, prove the truth of the fact, as related in ſcripture, and de⯑monſtrate, that the univerſal deluge could not be [129] accompliſhed by any other cauſe than the will of the Deity.
Beſides, it is apparent, that it was not at one time, nor by the ſudden effect of a deluge that the ſea left uncovered thoſe continents which we inhabit: It is certain, from the au⯑thority of ſcripture, that the terreſtrial Paradiſe was in Aſia, and that Aſia was inhabited before the deluge; conſequently, the waters, at that period, covered not this large portion of the globe. The earth, before the deluge, was near⯑ly the ſame as now. This enormous quantity of water, poured out by Divine juſtice upon guilty men, deſtroyed every living creature; but it produced no change on the ſurface of the earth; it deſtroyed not even the plants which grew up⯑on it; for the pigeon returned to the ark with an olive branch in her bill.
Why then ſhould we ſuppoſe, with many na⯑turaliſts, that the waters of the deluge totally changed the ſurface of the globe, even to the depth of two thouſand feet? Why imagine that the deluge tranſported thoſe ſhells which are found at the depth of ſeven or eight hundred feet, immerſed in rocks and in marble? Why refer to this event the formation of hills and mountains? And how is it poſſible to imagine, that the wa⯑ters of the deluge tranſported banks of ſhells of 100 leagues in length? I perceive not how they can perſiſt in this opinion, unleſs they admit a double miracle, one to create water, and ano⯑ther [130] to tranſport ſhells. But, as the firſt only is ſupported by holy writ, I ſee no reaſon for ma⯑king the ſecond an article of faith.
On the other hand, if the waters of the deluge had retired ſuddenly, they would have tranſport⯑ed ſuch immenſe quantities of mud and other impurities, as would have rendered the land un⯑ſit for culture till many ages after the inunda⯑tion. In the inundation which happened in Greece, the country that was covered remained barren for three centuries*. Thus the deluge ought to be regarded as a ſupernatural mode of chaſtifing the wickedneſs of men, not as an ef⯑fect proceeding from any natural cauſe. The univerſal deluge was a miracle, both in its cauſe and in its effects. It appears from the ſacred text, that the ſole deſign of the deluge was the deſtruction of men and other ani⯑mals, and that it changed not in any manner the ſurface of the earth; for, after the retreat of the waters, the mountains, and even the trees, kept their former ſtations, and the land was ſuit⯑ed for the culture of vines and other fruits of the earth. It might be aſked, if the earth was diſſolved in the waters, or, if the waters were ſo much agitated as to tranſport the ſhells of India into Europe, how the fiſhes, which entered not into the ark, were perſerved?
The notion, that the ſhells were tranſported and left upon the land by the deluge, is the ge⯑neral [131] opinion, or rather ſuperſtition, of natura⯑liſts. Woodward, Scheutzer, and others, call petrified ſhells the remains of the deluge; they regard them as medals or monuments left us by God of this dreadful cataſtrophe, that the me⯑morial of it might never be effaced among men. Laſtly, they have embraced this hypotheſis with ſo blind a veneration, that they are only anxious to reconcile it with holy writ; and, in place of deriving any light from obſervation and experi⯑ence, they wrap themſelves up in the dark clouds of phyſical theology, the obſcurity and littleneſs of which derogates from the ſimplicity and dig⯑nity of religion, and preſents to the ſceptic no⯑thing but a ridiculous medley of human conceits and divine truths. To attempt an explanation of the univerſal deluge and of its phyſical cauſes; to pretend to give a detail of what paſſed during this great revolution; to conjecture what effects have reſuited from it; to add facts to the ſacred writings, ad to draw conſequences from theſe interpolated facts; is not this a preſumptuous deſire of ſcanning the power of the Almighty? The natural wonders wrought by his beneficent hand, in a uniform and regular manner, are al⯑together incomprehenſible; his extraordinary operations, or his miracles, ought, therefore, to impreſs us with an awful aſtoniſhment, and a ſilent reſpect.
It may ſtill be urged, that as the univerſal de⯑luge is an eſtabliſhed fact, is it not lawful to rea⯑ſon [132] [...] [] [...] [130] [...] [131] [...] [132] upon its conſequences? True. But you muſt commence with acknowledging, that the deluge could not poſſibly be the effect of any phyſical cauſe, you muſt regard it as an immediate ef⯑fect of the divine will; you muſt content your⯑ſelf with what is recorded in ſcripture; and you muſt, above all, avoid bleding bad philoſophy with the purity of divine truth. After taking theſe precautions, which a reſpect for the coun⯑ſels of the Almighty requires, what remains for examination upon the ſubject of the deluge? Does the ſcared writings tell us that the moun⯑tains were formed by the deluge? They tell us the reverſe. Do they inform us, that the agitation of the waters was ſo great, as to raiſe the ſhells from the bottom of the ocean, and to diſperſe them over the face of the earth? No: The ark moved gently on the ſurface of the waters. Do they tell us, that the earth ſuffered a total diſ⯑ſolution? By no means. The narration of the ſacred hiſtorian is ſimple and true; that of na⯑turaliſts is fabuious and complicated.
THE ſurface of the earth, like that of Ju⯑piter, is not divided into alternate bands or belts, parallel to the Aequator. It, on the contrary, is divided, from one pole to the other, into two belts of earth, and two of ſea. The firſt and principal belt is the antient Continent, the greateſt length of which is a line commen⯑cing at the moſt eaſtern point of the north of Tartary, and extending from thence to the neigh⯑bourhood of the gulf of Linchidolin, where the Ruſſians fiſh whales; from thence to Tobolſki; from Tobolſki to the Caſpin ſea; from the Caſ⯑pian ſea to Mecca; from Mecca to the weſtern part of the country inhabited by the Galli in [134] Africa; from thence to Monoemuci, or Mono⯑motapa; and, laſtly, to the Cape of Good Hope. This line is about 3600 leagues in length, and is never interrupted but by the Caſpian and the Red Sea, the breadth of which is inconſiderable, and ought not to be regarded, eſpecially when, like our ſeaſons, the whole ſurface of the globe is divided only into four parts.
This line may be conſidered as the middle of the antient Continent; for, in meaſuring the ſurface on each ſide of it, I find, that, on the left, there are 2471092¾ ſquare leagues; and, on the right, there are 2469687, which is an equality ſo ſurpriſing as to render it extremely probable that this line, which is the longeſt, at the ſame time really divides the contents of the antient Continent.
The Old Continent, then, conſiſts of about 4940780 ſquare leagues, which is a fifth part of the ſurface of the globe, and may be regarded as a large belt of earth, with an inclination to the equator of about 30 degrees.
The New Continent is another belt of earth, the greateſt length of which may be taken from the mouth of the river Plata to the lake of the Aſſiniboils. This line paſſes from the mouth of the river Plata to lake Caracara; from thence to Mataguais, Pocona, Zongo, Ma⯑riana, Morua, St Fe, and Carthagena; then it paſſes through the gulf of Mexico, and Jamaica, and Cuba; from thence along the peninſula of Florida, through Apalache, Chicachas; and from thence to St Louis, Fort le Sueur, and terminates in the country bordering on lake Aſſiniboils, the [136] extent of which is unknown. See plate II. of Geogr.
This line is only interrupted by the Gulf of Mexico, (which may be conſidered as a Medi⯑terranean ſea), is about 2500 leagues in length, and divides the New Continent nearly into two equal parts, that on the left containing 1069286⅚ leagues ſquare, and that on the right 1070926 [...]/12. It is the middle of the belt of land called the New Continent, and is likewiſe inclined to the equator about 30 degrees, but in an oppoſite direction; for that of the Old Continent ex⯑tends from the north-eaſt to the ſouth-weſt; but that of the New Continent from north-weſt to ſouth-eaſt. The ſuperficial contents of the Old and New Continents are about 7080993 ſquare leagues, which is not near a third part of the ſurface of the globe, which contains 25,000,000 ſquare leagues.
Of theſe lines, which divide both the Conti⯑nents into two equal parts, it may be remarked, that they both terminate at the ſame degrees of north and ſouth latitude; and that the two Continents make mutual advances, or projections, exactly oppoſite to each other, viz. thoſe on the African coaſt, from the Canary iſles to Guiney; and thoſe of America, from Guiana to the mouth of the Rio-Janeiro.
In the New Continent, we ſhall likewiſe find, that Terra Magellanica, the eaſtern part of Bra⯑ſil, of the country of the Amazons, of Guiana, and of Canada, are new lands when compared with Tucuman, Peru, Terra Firma, the iſlands in the Gulf of Mexico, Florida, the Miſſiſippi, and Mexico. To theſe obſervations may be add⯑ed two remarkable facts. The Old and New Continents are nearly oppoſite to each other. The Old Continent extends farther north of the equator than ſouth; but the New, farther ſouth than north. The centre of the Old Continent lies in the 16th or 18th degree of north latitude; and the centre of the New Continent lies in the [138] 16th or 18th degree of ſouth latitude, as if they were intended to counterbalance each other. There is another ſingular analogy between the two continents, though it appears to be more the effect of accident than thoſe juſt mentioned. Both continents might be divided into two por⯑tions, which would be ſurrounded on all ſides by the ſea, excepting the two ſmall iſthmus's of Suez and Panama.
Theſe general obſervations on the diviſion of the globe are the reſult of an attentive ſurvey. We ſhall not, upon this foundation, erect hy⯑potheſes, or indulge in reaſonings, which might lead to falſe concluſions. But, as the diviſion of the globe has never hitherto been conſidered under this point of view, I ſhall hazard a few remarks. It is not a little ſingular, that the longeſt line that can be drawn upon the two continents ſhould, at the ſame time, divide them into two equal parts. It is not leſs remarkable, that theſe two lines ſhould commence and ter⯑minate at the ſame degrees of latitude, and have the ſame inclination to the equator. Theſe re⯑lations may lead to general concluſions, of which we are ſtill ignorant. We ſhall afterwards ex⯑amine, in detail, the inequalities in the figure of the two continents, and ſhall only here remark, that the moſt antient countries ſhould be found in the neighbourhood of the above lines, and ſhould, at the ſame time, have the higheſt ele⯑vation; and that the more recent lands ſhould [139] be moſt remote from them, and likewiſe lie lower. Agreeable to this idea, the neweſt coun⯑tries in America would be the land of the Ama⯑zons, Guiana, and Canada. In examining the map of theſe countries, we perceive that they are every where divided by numberleſs lakes and rivers, which is a ſtill ſtronger indication of their recent origin. On the other hand, Tucu⯑man, Peru, and Mexico, are high mountains, and are ſituate near the line that divides the continent; circumſtances which ſeem to prove the ſuperior antiquity of theſe countries. Africa is alſo extremely mountainous, and at the ſame time very antient. In this part of the globe, Aegypt, Barbary, and the weſtern coaſt, as far as Senegal, can only be conſidered as new lands. Aſia is perhaps the moſt antient of all countries, eſpecially Arabia, Perſia, and Tartary. But the inequalities of this great diviſion of the globe, as well as thoſe of Europe, ſhall be treated in a ſeparate article. We ſhall only remark, in ge⯑neral, that Europe is a new country, as appears from thoſe univerſal traditions concerning mi⯑grations of different nations, and the origin of arts and ſciences. It is not long ſince Europe was full of marſhes and foreſts. But, in coun⯑tries antiently inhabited, there are few woods, lakes, or marſhes, a great deal of heath and ſhrubs, and many high mountains, with dry and barren tops; for men deſtroy woods, drain marſhes and lakes, and, in proceſs of time, give [140] an appearance to the face of the earth totally different from that of uninhabited or newly peopled countries.
A ſmall portion of the globe only was known to the antients. The whole of America, the Artic circle, Terra Auſtralis and Magellanica, and a great part of the interior regions of Afri⯑ca, were unknown to them. They knew not that the Torrid Zone was inhabited, although they had ſailed round Africa. About 2200 years ago, Neco King of Aegypt furniſhed ſome veſſels to the Phoenicians, who ſailed down the Red Sea, doubled the Cape of Good Hope, and the third year after their departure they entered the Mediterranean by the Straits of Gibraltar*. The antients, notwithſtanding, were totally ig⯑norant of the polarity of the loadſtone, although they knew its power of attracting iron; they knew not the cauſe of the tides; and they were uncertain whether the ocean ſurrounded the globe. Some of them, indeed, ſuſpected that it might be ſo; but theſe conjectures were ſo ill founded, that none of them ever dreamed of its being poſſible to circumnavigate the earth. Ma⯑gellan, in the year 1519, was the firſt who at⯑tempted this great voyage; and he accompliſh⯑ed it in 1124 days. Francis Drake, in the 1577, was the ſecond; and he performed it in 1056 days. Thomas Cavendiſh ſet out upon this voyage in 1586, and finiſhed it in 777 days.
[141] Theſe celebrated navigators were the firſt who gave a phyſical demonſtration of the ſphe⯑ricity and extent of the circumference of the earth. The antients, though they travelled much, had no adequate idea of the extent of the globe. They were equally ignorant of the trade-winds, which are ſo uſeful in long voy⯑ages. Their limited knowledge in geography, therefore, ought not to ſurpriſe us, eſpecially when it is conſidered, that, notwithſtanding the many advantages derived from the mathematical ſciences, and from the diſcoveries of navigators, many points remain ſtill undetermined, and vaſt regions are yet undiſcovered. Of the countries in the neighbourhood of the ſouth pole, we on⯑ly know that they exiſt, and that they are ſepa⯑rated from the other continents by the ocean*. Much, likewiſe, remains to be diſcovered con⯑cerning the lands near the north pole: And, it is a ſubject of regret, that, for a century paſt, the ardour for diſcovering new countries has greatly abated. The nations of Europe ſeem, and perhaps they are right, more diſpoſed to in⯑creaſe the value of thoſe countries they have al⯑ready diſcovered, than to conquer new ones.
The diſcovery, however, of the ſouthern con⯑tinent, would be a grand object of curioſity, and might be attended with the greateſt advan⯑tages. A few of its coaſts have been recogni⯑ſed; but thoſe navigators who have attempted [142] the diſcovery, have been always prevented from reaching land by large bodies of ice. The thick fogs which infeſt thoſe ſeas is another obſtacle. But, notwithſtanding all theſe inconveniencies, it is probable, that, by ſetting out from the Cape of Good Hope at different ſeaſons, part of this new world might ſtill be diſcovered.
But another method might, perhaps, be atten⯑ded with more ſucceſs. To avoid the fogs and the ice, the diſcovery might be attempted, by departing from Baldivia, or ſome other port on the coaſt of Chili, and traverſiong the ſouth ſea under the 50th degree of ſouth latitude. This navigation appears not to be hazardous; and it is probable that it would be attended with the diſcovery of new lands; for the regions about the ſouth pole, ſtill unknown, are ſo extenſive, that they may be computed to be about a fourth part of the globe; and conſequently may con⯑tain a country as large as the whole of Europe, Aſia, and Africa.
While we remain ignorant of this part of the earth, we cannot determine the proportion the ſurface of the land bears to that of the ocean; from what we do know, it appears that there is more ſea than land.
To acquire an idea of the vaſt quantity of water in the ocean, we muſt ſuppoſe a medium depth, for example, that of 200 fathoms, or the ſixth part of a league. Upon this ſuppoſition, there is as much water in the ocean as would be [143] ſufficient to cover the whole globe to the depth of 600 feet; or, if collected into one maſs, it would form a globe of 60 leagues in diameter.
It is alledged by navigatiors, that the latitudes near the ſouth pole are much colder than the ſame latitudes towards the north. But this o⯑pinion ſeems to have no foundation. It ſeems to have been adopted from the circumſtance of the ice appearing the latitudes where none is ever found in the northern ſeas. But this effect may be owing to ſome peculiar cauſes. After the month of April, there is no ice on this ſide of 67 or 68 degrees of north latitude; and the ſa⯑vages of Acadia and of Canada ſay, that, if the ice be not melted in April, it indicates a cold and rainy ſummer. The year 1725 was diſtinguiſh⯑ed by an almoſt perpetual rain; and in April, the ice in the northern ſeas was not only not melted at the 67th degree, but, on the 15th of June, it was found in lat. 41 or 42*.
Great quantities of floating ice appear in the north ſeas, eſpecially at conſiderable diſtances from land. They come from the Tartarean ſea into that of Nova Zembla and other parts of the Frozen ocean. I have been aſſured by people worthy of credit, that an Engliſh Captain, call⯑ed Manſon, inſtead of ſearching for a paſſage to China between the northern lands, directed his courſe ſtraight to the pole till he arrived within two degrees of it; and that, in this courſe, [144] he found an open ſea, and no ice; which is a clear proof that the ice is always formed near the land, and never in an extenſive ſea: For, though it ſhould be ſuppoſed, contrary to pro⯑bability, that the cold was ſo intenſe at the pole as to freeze the ſurface of the ſea, it is ſtill in⯑conceivable how theſe enormous floating maſſes could be formed, without being attached to the land, from which they are again ſeparated by the heat of the ſun. Two veſſels ſent by the Eaſt India Company, in 1739, to diſcover land in the ſouth ſeas, found boards of ice in lat. 47 or 48; but they were not very diſtant from the ſhore, which was in view, though the veſſels could not make their landing good*. Theſe boards of ice muſt have been detached from the lands in the neighbourhood of the ſouth pole; and it may be conjectured that they follow the courſe of ſome large rivers in theſe unknown regions, in the ſame manner as the Oby, the Je⯑niſca, and other great rivers which fall into the north ſeas, carry down boards of ice, which ſhut up, during the greateſt part of the year, the ſtraits of Waigat, and render the ſea of Tartary, by this courſe, altogether inacceſſible; while, be⯑yond Nova Zembla, and nearer the pole, where there is little land and few rivers, boards of ice are leſs frequent, and the ſea is more navigable. Hence, if any farther attempts be made to find a paſſage to China and Japan by the north ſeas, [145] it will, perhaps, be neceſſary to keep at a diſtance from the land and the ice, to ſtear directly to⯑wards the pole, and to explore the moſt open ſeas, where unqueſtionably there is little or no ice: For it is well known, that ſalt water can take on a greater degree of cold, without freezing, than freſh water after it is congealed; conſe⯑quently, the exceſſive cold at the pole may ren⯑der the ſea colder than ice, without freezing its ſurface. Beſides, at 80 or 82 degrees, the ſea, though mixed with ſnow and freſh water, is ne⯑ver frozen, excepting near the coaſts. From the united teſtimony of ſeveral navigators, it is apparent, that there is a paſſage from Europe to China by the north ſea: The reaſon why it has ſo often been in vain attempted is, that fear prevented the undertakers from keeping at a ſufficient diſtance from the land, and from ap⯑proaching the pole, which they probably ima⯑gined to be an immenſe rock.
William Barents, however, who, like many others, had run aground in his voyage, never doubted of the exiſtence of ſuch a paſſage, or that, if he had kept farther from land, he would have found an open ſea without ice. The Ruſ⯑ſian navigators ſent by the Czar to reconnoitre the north ſea, relate, that Nova Zembla is not an iſland, but a part of Tartary, and that, to the north of it, there is a free and open ſea. A Dutch voyager affirms, that whales are occaſio⯑nally thrown upon the coaſts of Corea and of [146] Japan, with European harpoons ſticking in their backs. Another Hollander alledges, that he had penetrated to the pole itſelf, and aſſures us, that it was as warm as at Amſterdam in ſummer. One Goulden, an Engliſhman, who had made above thirty voyages to Greenland, related to Charles II. that two Dutchmen, who ſailed along with him, having been unſucceſsful in fiſhing off the coaſt of the Iſle of Edges, reſolved to proceed northward; that, upon their return, fifteen days after, they told him, that they had been at the 89th degree of latitude, where they found no ice, but an open, deep ſea, like that in the Bay of Biſcay; and that they ſhowed him the two ſhips journals, in ſupport of what they advanced. In fine, it is related in the Philoſo⯑phical Tranſactions, that two navigators, who engaged in the diſcovery of this paſſage, pene⯑trated 300 leagues to the eaſt of Nova Zembla; but that the Eaſt India Company, who thought they had an intereſt in preventing the diſcovery, allowed them not to return*. But the Dutch Eaſt India Company, who believed themſelves intereſted in the diſcovery, having made unſuc⯑ceſful attempts on the European ſide, tried to find it by the way of Japan; and they would probably have ſucceeded, if the Emperor of Ja⯑pan had not prohibited all ſtrangers from navi⯑gating on the coaſts of the lands of Jeſſo. This paſſage, therefore, cannot be found but by [147] ſteering directly to the pole beyond Spitzbergen, or rather by keeping the open ſea between Nova Zembla and Spitzbergen, under the 79th degree of latitude. For the reaſons already given, there is no occaſion to dread ice, even under the Pole itſelf; for there is no example of a large ſea freezing at a great diſtance from land. The on⯑ly ſea that freezes totally is the Black Sea, which is narrow, contains little ſalt, and receives from the northern countries a number of rivers, and large boards of ice. If we may credit hiſtorians, this ſea, in the time of the Emperor Coprony⯑mus, froze to the depth of 30 cubits. This may be an exaggeration: But that it freezes every winter is certain, while open ſeas, 1000 leagues nearer the Pole, never do. This can only be explained from the ſuperior ſaltneſs, and the comparatively ſmall quantity of ice-boards which thoſe ſeas receive.
Theſe boards of ice, which have been regard⯑ed as invincible obſtacles to navigation near the Poles, only prove the exiſtence of large rivers in the neighbourhood of the places where they ap⯑pear; they alſo demonſtrate the exiſtence of vaſt continents, from which theſe rivers derive their ſources; and, therefore, we ought not to be diſ⯑couraged by their appearance: Beſides, very little reflection will convince us, that theſe boards of ice muſt be confined to particular places; that it is impoſſible they ſhould occupy the whole circle in which the ſouthern continent is [148] ſuppoſed to be contained; and, therefore, if a different route were taken, we have reaſon to hope for ſucceſs. From the deſcription of New Holland, given by Dampier, and others, it is probable, that this part of Terra Auſtralis, which is, perhaps, a part of the ſouthern continent, is a country leſs antient than what remains to be diſ⯑covered. New Holland lies low; it has neither mountains nor rivers; it is thinly inhabited, and the natives have no induſtry. All theſe circum⯑ſtances induce us to think, that the ſavages of New Holland are ſimilar to thoſe of the Ama⯑zons, and of Paraguay in America. In Peru and Mexico, which are the moſt elevated, and, of courſe, the moſt antient countries of America, the manners of the inhabitants were poliſhed; and they were divided into diſtinct nations, go⯑verned by ſovereigns and by laws. Savages, on the contrary, are always found in low and new countries. Hence we may preſume, that, in the elevated and interior parts of the ſouthern con⯑tinent, from which iſſue thoſe large rivers that carry down boards of ice to the ſea, there are men united by the bonds of ſociety.
The interior parts of Africa are nearly as little known to us as they were to the antients. They had circumnavigated this immenſe peninſula; but they have neither left us charts, nor deſcrip⯑tions of its coaſts. Pliny tells us, that this voyage was performed in the days of Alexander the Great; that the wrecks of ſome Spaniſh ſhips [149] were found in the Arabian ſea; and that Hanno, the Carthaginian general, had ſailed from Gades to the Arabian gulf, and had written a relation of the voyage. He farther informs us, that, in the days of Cornelius Nepos, one Eudoxus, who had been perſecuted by King Lathurus, was obliged to fly; that he departed from the Ara⯑bic gulf, and arrived at Gades; and that, previ⯑ous to this period, Spain carried on a trade by ſea with Aethiopia.*. But, theſe antient teſti⯑monies notwithſtanding, we are of opinion, that they never doubled the Cape of Good Hope; and every man conſidered the voyage of the Portugueſe to the Eaſt Indies as a new diſcove⯑ry. It will not be incurious to ſee the ſenti⯑ments entertained of this ſubject in the ninth century. 'In our days, a diſcovery has been made which was totally unknown to thoſe who lived before us. No man believed, or could ſuſpect, that the ſea which reaches from the Indies to China had any communication with the ſea of Syria. But we have lately found, according to my information, in the Mediterranean, or ſea of Roum, the wreck of an Arabian ſhip which had been ſtaved to pieces by a tempeſt; ſome of theſe pieces had been carried, by the wind and the waves, into the ſea of the Cozars; from thence round to the Mediterranean, and along that ſea to the coaſt of Syria. This is a demonſtration that the [150] ocean ſurrounds China and Cila, the extremity of Turqueſton, and the country of the Cozars, and that, at laſt, it enters by the Straits, and waſhes the borders of Syria. The evidence ariſes from the conſtruction of the veſſel; for there are no ſhips but thoſe of Siraf whoſe planks are not nailed. But the veſſel above mentioned had all her planks ſtitched together in a manner peculiar to the Arabians. But all veſſels belonging to the Mediterranean, and coaſt of Syria, have their timbers faſtened with nails*.'
I ſhall ſubjoin the remarks added by the tranſ⯑lator of this antient relation.
'Abuziel remarks, as a thing perfectly new, that a veſſel had been carried from the Indian ſea, and thrown upon the coaſt of Syria. To find a paſſage for it into the Mediterranean, he ſuppoſes, that there is a great extent of ſea beyond China, which communicates with the ſea of the Cozars, or of Muſcovia. The ſea beyond Cape Current was entirely unknown to the Arabians, on account of the extreme hazard of navigating it, and becauſe the con⯑tinent was inhabited by a people ſo barbarous, that it was impoſſible either to conquer them, or to civilize them by commerce. The Por⯑tugueſe found not, from the Cape of Good Hope to Soffala, any Moors who had an eſta⯑bliſhed [151] ſettlement, like thoſe in all the maritime villages as far as China, which was the fartheſt place known to geographers. But they could not tell whether the Chineſe ſea communi⯑cated with that of Barbary by the extremity of Africa; they only deſcribed it to the coaſt of Zinga or Caffraria. We cannot, therefore, heſitate in pronouncing, that the firſt diſcovery of the paſſage of this ſea, by the Cape of Good Hope, was made by the Europeans, under the command of Vaſco de Gama, or, at leaſt, a few years before he doubled that Cape, if we may credit ſome ſea charts of an older date, where the Cape is marked under the name of Fronteira da Africa. Antony Galvan relates, upon the teſtimony of Franciſco de Souſa Ta⯑vares, that, in 1528, the Infant Don Ferdi⯑nand ſhewed him a ſimilar chart from the monaſtery of Acoboca, dated 120 years before, copied, perhaps, from that ſaid to be in the treaſury of St Marc at Venice, on which the point of Africa is likewiſe delineated, accor⯑ding to the evidence of Ramuſio,' &c.
The ignorance of theſe ages concerning the navigation round Africa is not, perhaps, ſo ſingular as the ſilence of the editor of this an⯑tient relation with regard to the paſſages in He⯑rodotus, Pliny, &c. which we have quoted, and which prove that the antients had ſailed round Africa.
[][152] However this matter ſtands, the coaſts of Afri⯑ca are now well known. But all the attempts that have been made to penetrate into the interior parts, have not furniſhed us with exact accounts. It would be a great object to go far up the coun⯑try, by means of Senegal, or ſome other great river, and eſtabliſh ſettlements. According to every appearance, we ſhould there find a coun⯑try as rich in precious metals as Peru or Braſil. It is well known, that the rivers of Africa a⯑bound in gold duſt; and, as the country is very high and mountainous, and is, beſides, ſituated under the equator, it admits not a doubt, that it contains, as well as America, mines of the hea⯑vieſt metals, and ſtones of the hardeſt and of the moſt compact texture.
The vaſt extent of north and eaſt Tartary is but a late diſcovery. If the Ruſſian charts be juſt, we know the whole coaſt of this part of Aſia; and it appears, that, from the termination of Eaſt Tartary to North America, is not above 400 or 500 leagues. It has even been lately re⯑duced to a much ſhorter ſpace. In the Amſter⯑dam Gazette of 24th January 1747, under the article Peterſburgh, it is alledged, that M. Stalle⯑ravoit had diſcovered, beyond Kamtſchatka, one of the North American iſles, and that he had de⯑monſtrated that we might paſs from Ruſſia to America by a very ſhort paſſage. The Jeſuites and other miſſionaries alſo pretended to have known ſavages in Tartary, whom they had ca⯑techized in America, which ſuppoſes the paſſage [153] to be indeed very ſhort*. Charlevoix would have us believe, that the old and new continents are united in the northern parts. He ſays, that ſome late voyages of the Japaneſe make it pro⯑bable that the paſſage we have been mentioning is only a bay, beyond which we may paſs, by land, from Aſia to America. But this notion requires confirmation; for it has always been thought, that the continent of the North Pole is probably ſeparated from all other continents, as well as that of the South Pole.
Aſtronomy and navigation have reached to ſo high a pitch of perfection, that we may reaſon⯑ably hope ſoon to have an exact knowledge of the whole ſurface of the globe. The antients, who were ignorant of the mariner's compaſs, were able to diſcover only a ſmall part of it. Some pretend that the Arabians invented this inſtrument, and that, by means of it, they car⯑ried on trade with India as far as China†. But this notion has always appeared to me to be de⯑ſtitute of foundation; for there is not in the Arabian, Turkiſh, or Perſian languages, a word that ſignifies a mariner's compaſs: They uſe the Italian word boſſola. Even at this moment, they can neither make compaſſes nor give polarity to the needle. They purchaſe them from the Europeans. Father Martini alledges, that the Chi⯑neſe have been acquainted with the compaſs theſe [154] 3000 years*. If theſe facts be true, how ſhould it happen that they have made ſo little uſe of it? Why, in their voyages to Cochinchina did they take a longer courſe than was neceſſary? Why did they always limit themſelves to the ſame ex⯑peditions, the longeſt of which was to Java and Sumatra? And why did they not diſcover, be⯑fore the Europeans, a vaſt variety of iſlands and of fertile countries in their own neighbourhood, if they poſſeſſed the art of navigating in the o⯑pen ſeas? It was but a few years after the diſ⯑covery of this wonderful quality of the load⯑ſtone, that the Portugueſe doubled the Cape of Good Hope, and traverſed the African and In⯑dian oceans, and that Chriſtopher Columbus ſailed to America.
It was not difficult to conjecture, that immenſe regions exiſted in the weſtern part of the globe; for, on computing what was known of it, name⯑ly, the diſtance from Spain to China, and attend⯑ing to the revolution of the earth, or of the hea⯑vens, it was eaſy to perceive, that a greater ex⯑tent lay to the weſt than what had been already diſcovered on the eaſt. That the antients found not the new world, was not owing to a deficien⯑cy in aſtronomical ſcience, but ſolely to their ignorance of the compaſs. The paſſages of Plato and of Ariſtotle, which mention countries far beyond the Pillars of Hercules, ſeem to indicate that ſome mariners had been driven by a tempeſt [155] on the coaſt of America, from which they had returned with infinite labour. But, ſuppoſing the antients had been thoroughly convinced that ſuch a continent exiſted, being ignorant of the compaſs, they could not poſſibly derive any ad⯑vantage from it.
I acknowledge, that it is not abſolutely im⯑poſſible for reſolute men, with no other guide than the ſtars, to ſail in open ſeas. The antients were in poſſeſſion of the Aſtrolabe. They might take their departure from France or Spain, and ſail to the weſt by always keeping the polar ſtar on the right hand; and, by frequent ſoundings, they might keep nearly in the ſame latitude. It was unqueſtionably by keeping the pole-ſtar on their left, that the Carthaginians mentioned by Ariſtotle were enabled to return from theſe diſtant regions. But it will ſtill be allowed, that ſuch a voyage muſt have been regarded as a raſh and hazardous enterpriſe. We ought not, therefore, to be ſurpriſed, that the antients never conceived ſuch a project.
Before the expedition of Columbus, the Azores, the Canaries, and Madeira, had been diſcovered. It had been remarked, that, when the weſt winds continued long to blow, the ſea threw upon the coaſts of theſe iſlands pieces of ſtrange wood, canes of an unknown ſpecies, and even dead bodies, which, by ſeveral marks, were known to be neither Europeans nor Africans*.
[156] Columbus himſelf remarked, that, on the weſt coaſts, certain winds blew for ſome days, which he was perſuaded proceeded from land. But, though he had all theſe advantages over the an⯑tients, and likewiſe the compaſs, the difficulties to be encountered were ſo great, that nothing leſs than ſucceſs could have juſtified the en⯑terpriſe. Suppoſe, for a moment, that the continent of America had been 1000 or 1500 leagues more diſtant, a circumſtance which Co⯑lumbus could neither foreſee nor prevent, he never would have arrived, and perhaps this vaſt country might ſtill have remained undiſcovered. This conjecture receives additional force, when it is conſidered, that Columbus, though the ableſt navigator of his age, was ſeized with terror and aſtoniſhment in his ſecond voyage to the New World: As, in his firſt voyage, he found no⯑thing but iſlands, he directed his courſe more to the ſouth in queſt of a continent; but found himſelf ſtopped by currents, the great extent of which, and their uniform oppoſition to his courſe, obliged him to direct his ſearch more to the weſt. He imagined, that it was not currents which prevented him from advancing to the ſouth, but that the ſea was riſing to the heavens, and that both perhaps touched each other in the ſouthern parts: Thus, in great undertakings, the moſt trifling difficulty may ſometimes turn a man's brain, and extinguiſh his courage.
WE have demonſtrated, in the firſt article, that the earth, in conſequence of the mutual attraction between the particles of mat⯑ter, and of the centrifugal force which reſults from its diurnal revolution, behoved to aſſume the figure of a ſpheroid, the two diameters of which differ about a 230th part; and that no⯑thing but the changes made on its ſurface by the motions of the air and of the waters, could aug⯑ment this difference, in the manner alledged by thoſe who meaſured a degree under the equator, and another within the polar circle. This fi⯑gure of the earth, which agrees ſo well with the laws of hydroſtatics and with our theory, indi⯑cates [158] that, at the time it aſſumed its figure, it was in a ſtate of fluidity. We have alſo pro⯑ved, that the projectile motion, and the motion of rotation, were impreſſed at the ſame time, and by the ſame impulſe. It will the more readily be admitted, that the earth was originally in a ſtate of liquefaction, when it is conſidered, that the greateſt part of the materials of which this globe is compoſed, are either vitrifications, or vi⯑trifiable by fire. The impoſſibility of rendering the earth fluid by the operation of waters con⯑firms this hypotheſis; becauſe there is infinitely more earth than water; and the water is not able to diſſolve ſand, rocks, and hard minerals.
It is, therefore, evident, that the earth aſſum⯑ed its figure when in a melted ſtate: And, to purſue our theory, it is natural to think, that the earth, when it iſſued from the ſun, had no other form but that of a torrent of melted and inflamed matter; that this torrent, by the mu⯑tual attraction of its parts, took on a globular figure, which its diurnal motion changed into a ſpheroid; that, when the earth cooled, the va⯑pours, which are expanded like the tail of a co⯑met, gradually condenſed, fell down in the form of water upon the ſurface, depoſiting, at the ſame time, a ſlimy ſubſtance, mixed with ſul⯑phur and ſalts, part of which was carried, by the motion of the waters, into the perpendicu⯑lar fiſſures of the ſtrata, and produced metals; and the reſt remained on the ſurface, and gave [159] riſe to the vegetable mould, which abounds, in different places, with more or leſs of animal and vegetable particles, the organization of which is not obvious to the ſenſes.
Thus the interior parts of the globe were ori⯑ginally compoſed of vitrified matter; and, I believe, they continue ſo at preſent. Above this vitrified matter, were placed thoſe bodies which the fire had reduced into the ſmalleſt particles, as ſands, which are only portions of glaſs; and, above theſe, pumice ſtones, and the ſcoriae of melted matter, which produced the different clays. The whole was covered with water to to the depth of 5 or 600 feet*, which origina⯑ted from the condenſation of the vapours, when the earth began to cool. This water depoſited a ſtratum of mud, mixed with all thoſe matters which are capable of being ſublimed or exhaled by fire; and the air was formed of the moſt ſubtile vapours, which, from their levity, roſe above the water.
Such was the condition of the earth, when the tides, the winds, and the heat of the ſun, began to introduce changes on its ſurface. The [160] diurnal motion of the earth, and that of the tides, elevated the waters in the equatorial re⯑gions, and neceſſarily tranſported thither great quantities of ſlime, clay, and ſand, and by thus elevating theſe parts of the earth, they perhaps ſank thoſe under the poles about two leagues, as was formerly remarked: For the waters would eaſily reduce into powder pumice-ſtones, and other ſpungy parts of the vitrified matter upon the ſurface, and, by this means, excavate ſome places, and elevate others, which, in time, would produce iſlands and continents, and all thoſe inequalities on the ſurface, which are more conſiderable towards the equator than the poles. The higheſt mountains lie between the Tropics and the middle of the Temperate Zones, and the loweſt from the polar circles towards the poles. Between the Tropics are the Cordeliers, moſt of the mountains of Mexico and the Braſils, the great and leſſer Atlas, the mountains of the Moon, &c. Beſides, both the land and the ſea have moſt inequalities between the tropics, as is evident from the incredible number of iſlands peculiar to thoſe regions.
However independent this hypotheſis, con⯑cerning the original ſtate of the globe, may be of my general theory, I have choſen to refer to it in this article, to ſhow the connection and poſſibility of the ſyſtem endeavoured to be eſta⯑bliſhed in the firſt article. It may only be re⯑marked, that my theory is not oppoſed by the [161] facts; that I take the earth nearly as it ſtands at preſent; and that I lay hold of none of thoſe ſuppoſitions which are often uſed in reaſoning concerning the former condition of this globe. But, as I here offer a new idea upon this ſub⯑ject of the ſediment depoſited by the waters, which, in my opinion, gave riſe to the upper ſtratum of the earth, it will not be improper to exhibit the reaſons upon which it is founded.
The vapours exhaled from the earth produce rain, dews, thunder, lightening, and other mete⯑ors. Theſe vapours, therefore, are mixed with particles of water, air, ſulphur, earth, &c.; and it is the ſolid earthy particles which conſtitute the ſlime or mud under conſideration. The pureſt rain-water depoſites a quantity of this mud; and, when a quantity of dew is collected, and allowed to corrupt, it produces a greater proportional quantity of mud, which is fat, unctuous, and of a reddiſh colour.
The upper ſtratum of the earth is compoſed of this mud, mixed with particles of animal and vegetable ſubſtances, or rather with particles of ſtone and ſand. It may be remarked, that moſt arable land is reddiſh, and more or leſs blended with heterogeneous matters. The particles of ſtone or of ſand found in it are of two kinds; the one is groſs and heavy, the other fine, and ſometimes impalpable. The groſs is detached from the inferior ſtratum by labouring the ground; or rather, the upper ſtratum, by pene⯑trating [162] the inferior, which is compoſed of ſand or gravel, forms what is called fat, or fertile ſand. The finer ſpecies proceeds from the air, falls down with the dew or rain, and intimately incorporates with the vegetable mould, or upper ſtratum. This laſt is nothing more than the duſt, tranſported by the air, and again depoſited during a moiſt atmoſphere. When the quantity of this mud is great, in proportion to the par⯑ticles of ſtone or ſand, the ſoil is red and fer⯑tile; if it be conſiderably mixed with animal and vegetable ſubſtances, it is blackiſh; but, if the quantity of mud, and of vegetable and ani⯑mal ſubſtances be ſmall, the ſoil is white and barren; and, even when the particles of ſand, ſtone, or chalk, which compoſe theſe barren ſoils, are mixed with a conſiderable quantity of animal and vegetable ſubſtances, they become black and light, but have very little fertility. According, therefore, to the different proportions of theſe three ingredients, ſoils are more or leſs fertile, and differently coloured.
In order to acquire diſtinct ideas concerning the ſtrata of the earth, we ſhall take for an ex⯑ample the pits at Marly-la-Ville, which are ex⯑ceedingly deep. It is ſituated in a high, but flat and fertile country, and its ſtrata lie hori⯑zontally. I procured ſpecimens of all theſe ſtrata in their order from M. Dalibard, an eminent botaniſt, and a man of ſcience; and, after ha⯑ving proved the matters they reſpectively conſiſt [163] of with aqua fortis, I arranged them in the fol⯑lowing table.
| Feet. | Inch. | ||
| 1. | A free reddiſh earth, mixed with a large quantity of mud, a little vi⯑trifiable ſand, and a greater pro⯑portion of calcinable ſand, or gra⯑vel | 13 | |
| 2. | A free earth mixed with gravel and with more vitrifiable ſand | 2 | 6 |
| 3. | Mud mixed with a large quantity of vitrifiable ſand, which made but a ſmall eſſerveſcence with a⯑qua fortis | 3 | |
| 4. | Hard marle, which eſſerveſced violently with aqua fortis | 2 | |
| 5. | A marley ſtone, very hard | 4 | |
| 6. | Marle in powder, mixed with vi⯑trifiable ſand | 5 | |
| 7. | Fine vitrifiable ſand | 1 | 6 |
| 8. | Marle reſembling earth, mixed with a little vitrifiable ſand | 3 | 6 |
| 9. | Hard marle, in which was found genuine flint | 3 | 6 |
| 10. | Gravel, or marle in powder | 1 | |
| Carried over | 39 | ||
| [164] | Brought over | 39 | |
| 11. | Eglantine, a hard ringing ſtone, of the grain of marble | 1 | 6 |
| 12. | Marley gravel | 1 | 6 |
| 13. | Marle in the form of hard ſtone, with a fine grain | 1 | 6 |
| 14. | Marle like ſtone, with a coarſer grain | 1 | 6 |
| 15. | Marle ſtill more groſs | 2 | 6 |
| 16. | Fine vitrifiable ſand, mixed with foſſil ſea-ſhells, which had no co⯑heſion with the ſand, and which ſtill preſerve their natural colours | 1 | 6 |
| 17. | Fine gravel, or marle-duſt | 2 | |
| 18. | Marle in the form of a hard ſtone | 3 | 6 |
| 19. | Marle in the form of coarſe powder | 1 | 6 |
| 20. | Hard ſtone, calcinable like marble | 1 | |
| 21. | A gray vitrifiable ſand, mixed with foſſil ſhells, particularly with oi⯑ſters and ſpondyles, which had no coheſion with the ſand, and were not petrified | 3 | |
| 22. | A white vitrifiable ſand, mixed with the ſame ſhells | 2 | |
| 23. | A vitrifiable ſand, with red and white ſtreaks, and mixed with the ſame ſhells | 1 | |
| 24. | A coarſer vitrifiable ſand, mixed with the ſame ſhells | 1 | |
| Carried over | 64 | ||
| [165] | Carried over | 64 | |
| 25. | A fine, gray, vitrifiable ſand, mix⯑ed with the ſame ſhells | 8 | 6 |
| 26. | A fine unctuous ſand, with very few ſhells | 3 | |
| 27. | Brown free ſtone | 3 | |
| 28. | Vitrifiable ſand, ſtripped with red and white | 4 | |
| 29. | A white vitrifiable ſand | 3 | 6 |
| 30 | A reddiſh vitrifiable ſand | 15 | |
| Total depth of the pit | 101 |
I mentioned above, that I had examined all theſe ſubſtances with aqua fortis, becauſe no o⯑ther teſt can enable us to make real diſtinctions between earthy bodies of the ſame or of different appearances. Thoſe which efferveſce and ſud⯑denly diſſolve on the application of the aqua fortis, are generally calcinable. Thoſe, on the other hand, upon which that acid makes no im⯑preſſion, are vitrifiable.
From the above enumeration of ſtrata it is e⯑vident, that that the land at Marly-la-ville was for⯑merly covered with the ſea, to the depth of 75 feet, ſince ſhells are found 75 feet below the ſurface. Thoſe ſhells have been collected and depoſited by the water, along with the ſand which contains them; and the whole ſuperior ſtrata, excepting the uppermoſt, have been tranſ⯑ported thither by the motion of the waters, and [166] depoſited in the form of ſediment, as is appa⯑rent from their horizontal poſition, from the mixture of ſand, ſhells, and marle, which laſt is compoſed of decayed ſhells; and even the up⯑per ſtratum has been almoſt wholly formed of ſlime or mud, with a ſmall mixture of marle.
I have choſen this example, becauſe it is leaſt favourable to my theory; for it appears, at firſt view, difficult to conceive how the mud depo⯑ſited by the dew and rains ſhould produce a bed of vegetable ſoil 13 feet thick. But it ought to be remarked, that a ſoil of this thick⯑neſs is rarely to be found, eſpecially in high countries. The general run of ſoils are from three to four feet, and often they exceed not one foot. The ſoil is thickeſt in plains ſur⯑rounded with hills; becauſe the rains daily bring freſh ſupplies from the higher grounds. But, abſtracting from this ſuppoſition, it is plain, that the upper ſtrata formed by the ſea, are thick beds of marle. It is natural to think, that the upper ſtratum, above mentioned, was originally much thicker, and that, beſides the 13 feet, the ſea would leave a conſiderable quantity of marle. But this marle, being expoſed to the action of the air, of rains, and of the rays of the ſun, would ſoon be reduced into a fine powder. The ſea would not leave this land ſuddenly, but would continue for ſom time occaſionally to cover it, either by the motion of the tides, or by extraordinary ſwells during great ſtorms; and, [167] of courſe, the upper ſtratum would be mixed with mud, clay, and other ſlimy bodies. After being entirely above the reach of the waves, plants would begin to grow, and the ſoil would conſtantly accumulate, and be tinged with a reddiſh colour, by the mud depoſited from dews and rain. Culture would ſtill farther increaſe both its fertility and its thickneſs, and, by al⯑lowing the dews and rains to penetrate deeper, would in the end produce this ſoil of 13 feet.
I ſhall not here examine, whether the reddiſh colour of vegetable mould proceeds from a quan⯑tity of iron contained in the mud depoſited by rain and dews. This point, which is of ſome importance, ſhall be diſcuſſed when we come to treat of minerals. It is ſufficient to have given a view of the manner in which the upper ſtratum has been formed: We ſhall now prove, by other examples, that the formation of the interior ſtra⯑ta of the earth muſt likewiſe have originated from the operation of the waters.
The upper ſtratum of the globe, ſays Wood⯑ward, that magazine for the formation and ſup⯑port of animals and vegetables, is moſtly com⯑poſed of vegetable and animal matter, and is in perpetual fluctuation. All the animals and ve⯑getables which have exiſted ſince the creation, have ſucceſſively extracted from this ſtratum the materials of which their bodies are conſtructed; theſe they again reſtore at their diſſolution, where they remain prepared for the ſucceſſive forma⯑tion [168] of new bodies of the ſame ſpecies; the mat⯑ter which forms one body being naturally diſ⯑poſed to make another of the ſame kind*. In uninhabited countries, where the woods are never cut, nor the herbs brouzed by cattle, the ſoil is conſtantly augmenting. The ſoil, in all woods, even in thoſe which are occaſionally cut, is from 6 to 8 feet thick, and has originated from decayed leaves, and other parts of ve⯑getables. I have often remarked, upon an old Roman way which runs acroſs Burgundy, that the ſtones with which it was conſtructed are covered with a black mould of more than a foot thick, and nouriſhes trees of a conſiderable ſize. This ſoil could only be produced by the gradual and ſucceſſive deſtruction of vegetable bodies. As vegetables derive more of their ſubſtance from the air and from water, than from the earth, when they decay, they add more to the earth than they extracted from it. Beſides, foreſts collect and retain vapours and moiſure; and, of courſe, in old woods, the ſoil is greatly aug⯑mented. But, as animals reſtore much leſs to the earth than they take from it; and, as men conſume vaſt quantities of wood and herbs, for feuel and other purpoſes, it follows, that the ve⯑getable ſoil of populous countries muſt conti⯑nually diminiſh, and become, in time, like that of Arabia Petrea, and other eaſtern countries, which were firſt inhabited, where nothing is to [169] be found but ſand and ſalts; for the fixed ſalts of plants and of animals remain, while all the other parts volatilize, and are carried off by the air.
Let us next examine the poſition and forma⯑tion of the interior ſtrata. The earth, ſays Woodward, wherever it has been dug, is com⯑poſed of beds or ſtrata, one above another, in the ſame manner as if they had proceeded from ſucceſſive ſediments depoſited by water. The beds that lie deepeſt are thicker than thoſe im⯑mediately above them, and they grow gradual⯑ly thinner till they arive at the ſurface. Sea-ſhells, teeth, and bones of fiſhes, are found in theſe beds, and not only in thoſe which are ſoft, as chalk, clay, and marle, but even in beds of hard ſtone, marble, &c. Theſe productions of the ſea are incorporated with the ſtone, and, when ſeparated, leave in the ſtone the figure of their ſurface exactly delineated. 'I was abun⯑dantly aſſured,' ſays this author, 'that the cir⯑cumſtances of theſe things in remoter coun⯑tries were much the ſame with thoſe of ours here: That the ſtone, and other terreſtrial mat⯑ter, in France, Flanders, Holland, Spain, Italy, Germany, Denmark, Norway, and Sweden, was diſtinguiſhed into ſtrata, or layers, as it is in England: That thoſe ſtrata were divided by parallel fiſſures: That there were incloſed in the ſtone, and all the other denſer kinds of terreſtrial matter, great numbers of ſhells, and [170] other productions of the ſea; in the ſame man⯑ner as in that of this iſland. To be ſhort, by the ſame means I got ſufficient intelligence that theſe things were found in like manner in Bar⯑bary, in Egypt, in Guiney, and other parts of Africa: In Arabia, Syria, Perſia, Malabar, China, and other Aſiatick provinces: In Ja⯑maica, Barbadoes, Virginia, New England, Braſil, Peru, and other parts of America., p. 6. 41. 42. &c.
Woodward gives no authority for his aſſer⯑tion, that ſhells are found in the ſtrata of Peru. But as, in general, his facts are true, I doubt not but his information has been good; and I am perſuaded that ſhells exiſt in the ſtrata of Peru, as well as every where elſe. I make this re⯑mark on account of a doubt which has been entertained on this ſubject, and which ſhall af⯑terwards be conſidered.
In digging a well at Amſterdam, 232 feet deep, the ſtrata were arranged in the following order: 7 feet of vegetable ſoil; 9 feet of turf; 9 feet of ſoft clay; 8 feet of ſand; 4 of earth; 10 of clay; 4 of earth; 10 of ſand; 2 of clay; 4 of ſmall white ſand; 5 of dry earth; 1 of ſoft earth; 14 of ſand; 8 of clay mixed with ſand; 4 of ſand mixed with ſhells; then 102 feet of clay; and, laſtly, 31 feet of ſand*.
It is uncommon to dig ſo deep before we find water: But this experiment is remarkable in [171] many other reſpects. 1ſt, It demonſtrates that the ſea communicates not with the interior parts of the earth by means of filtration: 2d, That ſhells are found 100 feet below the ſurface in a country extremely low; and, conſequently, that the land of Holland has been elevated 100 feet by the ſediments of the ocean: 3d, It may be concluded, that the bed of clay of 102 feet, and the bed of ſand, 31 feet of which only had been dug, and whoſe actual thickneſs is unknown, lie near to the antient and original earth, which ex⯑iſted before the motion of the waters began to change its ſurface. In the firſt article, it was remarked, that, in order to diſcover the antient earth, we muſt dig in the northern, rather than in the ſouthern regions; and in the low and plain, rather than in the elevated countries. Theſe circumſtances nearly concurred in the pre⯑ſent caſe. We only wiſh that the pit had been dug deeper, and that the author had informed us, whether ſhells, or other ſea-bodies, were in⯑termixed with the laſt ſtrata of clay and of ſand. This experiment confirms what was above ad⯑vanced, that the ſtrata are always thicker in pro⯑portion to their depth.
The earth conſiſts of parallel and horizontal ſtrata, not in the plains only, but, in general, the hills and mountains have the ſame ſtructure. The ſtrata of the mountains are even more con⯑ſpicuous than thoſe of the plains; for the plains are commonly covered with great quantities of [172] ſand and earth brought from the higher grounds by the waters; and, therefore, to find the antient ſtrata, we muſt dig deeper in the plains than in the mountains.
I have often remarked, that, when the top of a mountain is level, its ſtrata are likewiſe level; but, when the top is not horizontal, the ſtrata follow the direction of its declivity. It has fre⯑quently been alledged, that the beds of quarries incline to the eaſt. But in all the chains of rocks which I have examined, I found, that theſe beds always follow the declivity of the hill, whether its direction be eaſt, weſt, ſouth, or north. In raiſing ſtones from the quarry, they are always ſeparated according to their natural poſition; and, if cut in a contrary direction, it is impoſſible to raiſe them of any conſiderable ſize. In all good maſonry, the workmen place the ſtones in the direction in which they lay in the quarry. If laid in an oppoſite poſition, they will ſpilt, and not be able to reſiſt the weight of the incumbent building. Hence we may conclude, that ſtones have been originally formed in hori⯑zontal beds; that theſe beds have been ſucceſſive⯑ly accumulated above each other, and have been compoſed of materials, the reſiſtance of which is ſtronger in that than in any other direction.
Every ſtratum, of whatever kind, whether it be horizontal or inclined, is of an equal thick⯑neſs through its whole extent. In the quarries round Paris, the ſtratum of good ſtone is but a⯑bout [173] 18 or 20 inches thick throughout. In the quarries of Burgundy, the ſtone is much thicker. The ſame inequalities take place in marbles. The white and black marbles are thicker than thoſe that are coloured; and there is a hard ſtone with which the people of Burgundy cover their houſes, that exceeds not an inch in thickneſs. Thus, different ſtrata differ much with regard to thickneſs; but each ſtratum uniformly preſerves the ſame thickneſs through its whole extent. This difference is ſo great, that ſtrata are to be found, from leſs than a line, to 1, 10, 20, 30, and 100 feet thick. Both antient and modern quarries, which are dug horizontally, the ſhafts of mines, and the working of lead, both longi⯑tudinally and tranſverſely, prove that ſtrata ex⯑tend a great way on all ſides. 'It is well known,' as the hiſtorian of the academy obſerves, 'that all ſtones have originally been a ſoft paſte, and that, as ſtones are almoſt every where to be met with, the ſurface of the earth, in all theſe places, at leaſt to a certain depth, muſt have conſiſted of mud and ſlime. The ſhells found in moſt quarries demonſtrate, that this mud was an earth diluted by the water of the ſea; and, conſequently, that the ſea once covered all theſe places; but the ſea could not cover them, without, at the ſame time, covering all places that were lower, or on the ſame level. Now, it is impoſſible that the ſea could cover all thoſe places where there are quarries, with⯑out [174] covering the whole ſurface of the globe. If the mountains were then formed, the ſea muſt alſo have covered them; for they are full of rocks and quarries, and ſhells are often found in them.'
'The ſea, then,' continues he, 'covered the whole earth; and hence all the beds of ſtone in the plains are horizontal and parallel: The fiſhes, therefore, were the moſt antient inha⯑bitants of the globe; for neither land-animals nor birds could exiſt. But how has the ſea retired into thoſe vaſt baſons which it now oc⯑cupies? The moſt natural ſuppoſition is, that the earth, at leaſt to a certain depth, was not all equally ſolid, but interſperſed with vaſt vaults or caverns, the arches of which would remain for a time, and at laſt ſuddenly fall in. The waters would then ruſh into theſe hol⯑lows, fill them up, and leave a part of the ſur⯑face dry, which would become a convenient habitation for land-animals and birds. The ſhells found in quarries ſtrongly confirm this idea; for nothing but the bony parts of fiſhes could be preſerved ſo long in the earth. Be⯑ſides, ſhells commonly lie in vaſt maſſes in cer⯑tain parts of the ſea, where they remain im⯑moveable, and form a ſpecies of rocks or banks; they could not, therefore, follow the ſea, which ſuddenly abandoned them. For this laſt rea⯑ſon it is, that we find ſuch numbers of foſſil-ſhells, and ſo few veſtiges of other fiſhes, which [175] is a farther proof that the waters retired with rapidity into their preſent baſons. When the vaults ſunk down, it is very probable that mountains were elevated by the ſame cauſe, and placed upon the ſurface with rocks and quarries already formed. But the beds of theſe quarries could not preſerve their original ho⯑rizontal poſition, unleſs they were raiſed ex⯑actly perpendicular to the ſurface, which would rarely happen. Thus, as we formerly remark⯑ed*, the beds of ſtone in mountains are all inclined to the horizon, though they be paral⯑lel to each other; for they changed not their poſition with regard to one another, but with regard only to the ſurface of the earth†.'
Theſe parallel beds of earth or of ſtone, which have been formed by ſediments of the ocean, often extend to conſiderable diſtances; we even find, in hills ſeparated by vallies, beds of the ſame materials upon equal levels. This obſer⯑vation has a perfect correſpondence with the equal altitudes of oppoſite hills. The truth of this fact may be eaſily eſtabliſhed; for, in all hills ſeparated by narrow vallies, where ſtone or marble is found on one hill, we uniformly find theſe very ſubſtances, at the ſame level, on the oppoſite hill. I have traced a quarry of marble 12 leagues in length; its breadth is alſo conſiderable, though I have not been able exact⯑ly to aſcertain it. I have often obſerved, that [176] this bed of marble has every where the ſame thickneſs; and that, in hills ſeparated by a val⯑ley of 100 feet deep, the ſame bed always ap⯑peared at the ſame altitude. I am firmly per⯑ſuaded, that this obſervation holds with regard to all quarries of ſtone or of marble that contain ſhells; but it applies not to beds of free-ſtone. We ſhall afterwards explain why free-ſtone is not diſperſed, like other matters, in horizontal beds, but in blocks, irregular both in form and poſition.
It has likewiſe been remarked, that, on the oppoſite ſides of ſtraits of the ſea, the ſtrata are the ſame. This obſervation is important, and may lead to the diſcovery of thoſe necks of land, or iſlands, that have been ſeparated from the Continent. It proves, for example, that Eng⯑land has been ſeparated from France, Spain from Africa, and Sicily from Italy: And it is to be regretted, that the ſame obſervation has not been made upon all ſtraits. I have no doubt but it will hold univerſally. We know not, whether, in the ſtraits of Magellan, the longeſt we are acquainted with, the ſame ſtrata are to be found at the ſame altitude; but we perceive, from very exact charts, that the oppoſite coaſts, which are high, have correſponding angles like thoſe ob⯑ſervable in our inland mountains; and this fur⯑ther proves Terra del Fuego to have been for⯑merly a part of the Continent of America. The ſame remark has been made with regard to the [177] ſtrait of Forbiſher; and the iſland of Frieſland appears to have been ſeparated from the conti⯑nent of Greenland.
The Maldiva iſlands are ſeparated from each other by ſmall branches of the ſea; and on each ſide of the oppoſite iſlands, the ſtrata of rocks, &c. are the ſame. Theſe iſlands, which, when taken together, extend about 200 leagues in length, were formerly one. They are divided into 13 provinces, called Cluſters. Every Cluſter contains a great number of ſmall iſlands, moſt of which will ſoon be under water. It is re⯑markable, that each of theſe 13 Cluſters is ſur⯑rounded with a chain of rocks of the ſame ſtone, and that there are only three or four ſmall and dangerous openings through which each of them can be approached. They are all placed in a line, with their ends to each other, and appear evidently to have been once a long mountain crowned with rock*.
Several authors, as Verſtegan, Twine, Sommer, but particularly Campbell, in his deſcription of the county of Kent, give ſtriking proofs that England was formerly joined to France, and that the neck of land which divides them had been carried off by the ſea, which retired, and left a great quantity of low marſhy ground along the ſouthern coaſts of England. As a farther proof of this fact, Dr Wallis has attempted to ſhow an affinity between the antient language of the [178] Gauls and of the Britains; and he adds ſeveral other remarks which ſhall be related in the fol⯑lowing articles.
If travellers obſerved the figure of lands, the poſition of mountains, and the windings of ri⯑vers, they would perceive that oppoſite hills are not only compoſed of the ſame materials, at the ſame altitudes, but that they are alſo nearly of an equal height. In all the places where I have travelled, I uniformly remarked this equality in the height of oppoſite hills, eſpecially when they are ſeparated by valleys not above a fourth or a third of a league wide. In valleys of greater width, it is difficult to judge of the height or e⯑quality of hills; for, on looking over a level and extenſive plain, it appears to riſe; and di⯑ſtant hills appear to ſink. But this is not the place to account for theſe phaenomena. Be⯑ſides, it is not eaſy to determine, by the eye, the middle of a large valley, unleſs there be a river in it. But, in narrow valleys, the judgment of the eye is more certain. That part of Burgun⯑dy comprehended between Auxerre, Dijon, An⯑tun, and Bar-ſur-ſeine, and of which a con⯑ſiderable portion is called le Bailliage de la Montagne, is one of the moſt elevated parts of France. From one ſide of theſe mountains, which are only of the ſecond order, the water runs to the ocean, and, from the other, to the Mediterranean. There are points of partition, as at Sombernon, Pouilli in Auxois, &c. where [179] the water may be turned at pleaſure, either to the ocean or to the Mediterranean. This high country is interſected with a number of ſmall valleys, and moſt of them are watered with ri⯑vulets. Here I have a thouſand times obſerved the correſponding angles of the hills, and their equality as to height; and I can with confidence affirm, that the ſaliant or prominent angles are uniformly oppoſed to the concave ones, and that the heights of the two ſides are nearly the ſame. The farther we advance in this high country, where are the points of partition mentioned a⯑bove, the mountains are the higher. But this height is always the ſame on the oppoſite ſides of the valleys, and the hills riſe or fall equally. The ſame obſervation I have repeatedly made in ſeveral other provinces of France; but they ex⯑tend not to very high mountains; for theſe are more irregular as to height, and often terminate in unequal points or peaks. In frequently tra⯑verſing the Alps and Appennines, I obſerved, that the angles, in effect, correſponded; but that it is almoſt impoſſible to judge, by the eye, con⯑cerning the equality or inequality in the heights of oppoſite mountains; becauſe their tops are loſt in the clouds.
The different ſtrata compoſing the earth are not arranged according to their ſpecific gravities. Beds of heavy matter are frequently placed above thoſe of lighter. Solid rocks are often ſupported by beds of earth, clay, or ſand, which [180] have much leſs ſpecific gravity. This is the caſe with moſt hills, and is eaſily perceived. But, in high mountains, the ſummits are not only rocks, but theſe rocks are ſupported by others; and this ſtructure runs through ſuch an extent of country, where one mountain riſes out of ano⯑ther, that it is difficult to determine whether they are founded on earth, or of what nature this earth is. I have ſeen rocks cut perpendi⯑cularly for ſome hundreds of feet; but theſe rocks reſted upon other rocks, without my be⯑ing able to perceive where they ended. May we not, however, be allowed to conclude from the leſs to the greater? Since the rocks of ſmall mountains, the baſes of which are viſible, reſt upon earths leſs heavy and leſs ſolid than ſtone, is it not reaſonable to think, that earth is like⯑wiſe the baſis of high mountains? Beſides, all I have here advanced tends to prove, that heavy bodies might be accumulated, by the motion of the waters, above light ones; and, if this really takes place in moſt hills, it is probable that it has happened in the manner pointed out by my theory. But, ſhould it be objected, that I had no reaſon to ſuppoſe, that, prior to the forma⯑tion of mountains, the heavier matter was below the lighter; I anſwer, that I affirm nothing with regard to this article; becauſe there are many ways by which this effect might be produced, whether the heavy matter was above or below, or placed indiſcriminately: For, in order to [181] conceive how the ſea could firſt form a moun⯑tain of clay, and then crown it with rocks, we have only to conſider, that the ſediments might be tranſported from different places, and that they might conſiſt of different materials. The ſea might tranſport from one place ſeveral ſedi⯑ments of clay, and afterwards depoſite ſediments of ſtony matter; either becauſe all the clay at the bottom, or on the coaſts, was exhauſted, and then the waves would attack the rocks; or, rather, becauſe the firſt ſediments were tranſ⯑ported from one place, and the laſt from a dif⯑ferent one. Beſides, the latter correſponds ex⯑actly with experience; for, it is a known fact, that beds of earth, ſtone, gravel, ſand, &c. fol⯑low no rule of arrangement, but are placed in⯑differently, and, as it were, by chance, one above another.
This chance, however, ought to have ſome rules, which can only be diſcovered by analogy and probable conjecture. We have ſeen, that, according to my theory of the formation of the globe, that its interior parts ſhould conſiſt of vi⯑trified matter, ſimilar to vitrified ſand, which is only the fragments of glaſs, and of which the clays are only the ſcoriae, or decompoſed parts. Agreeable to this ſuppoſition, the centre of the earth, and even near to the ſurface itſelf, ſhould be compoſed of glaſs or vitrified matter, and above this ſhould be found ſand, clay, and other ſcoriae. Thus the earth, in its original ſtate, [182] was a nucleus of glaſs, or of vitrified matter, either compact like glaſs, or divided like ſand, (for that circumſtance depends on the degree of heat applied); above this matter was ſand; and, laſtly, clay. The ſoil, or external covering, was produced from the air and the mud of wa⯑ter; and it is more or leſs thick according to the ſituation of the ground; more or leſs coloured, according to the different mixtures of mud, ſand, clay, and the parts of decayed animals and vegetables; and more or leſs fertile, according to the abundance or deficiency of theſe parts. To ſhow that this account of the formation of ſand and clay is not altogether imaginary, I ſhall add a few remarks.
I ſuppoſe the earth, in its firſt ſtate, to have been a ſpheroid of compact glaſs, covered with a thin cruſt of pumice-ſtone, and other ſcoriae of melted matter. The agitation of the air and of the water would ſoon reduce this cruſt of pumice into powder or ſand, which, by uniting into maſſes, would give riſe to free-ſtone and flints, the varieties of which, with regard to co⯑lour and denſity, depend upon the different de⯑grees of fineneſs of the ſand that compoſed them.
The conſtituent parts of ſand unite by the application of fire, become very hard, compact, and more or leſs tranſparent according to the purity of the ſand: But, on the other hand, when expoſed to the action of the air, it exfo⯑liates, [183] falls down in the form of earth, and may thus produce clays of different kinds. This duſt, which is ſometimes yellow, ſometimes brilliant, and is uſed to dry writings, is nothing elſe than a fine ſand, ſomewhat corrupted, and nearly re⯑duced to an elementary ſtate. In time, its par⯑ticles become ſo attenuated and divided, that they loſe the power of reflecting light, and ac⯑quire all the properties of clay. On examining a piece of clay, many of theſe ſhining or talky particles appear, they not having yet entirely loſt their original form. Sand, therefore, in proceſs of time, may produce clay; and this clay, by a farther diviſion, acquires the qualities of a mud or ſlime, a vitrifiable matter of the ſame nature with clay.
This theory is confirmed by daily experience. In waſhing ſand, the water becomes impreg⯑nated with a black, ſoft, fatty earth, which is a genuine clay. The mud ſwept from ſtreets paved with free-ſtone is black and very fat, and, when dried, it diſcovers itſelf to be an earth of the ſame nature with clay. Clay, taken from places where there is neither flint nor free-ſtone, and diluted with water, always pre⯑cipitates a great quantity of vitrifiable ſand.
But, what clearly demonſtrates the exiſtence of ſand, and even of flint and galſs in clay, is, that the reunion of its parts, by the action of fire, reſtores it to its original form. Clay, when heated to the degree of calcination, is covered with [184] a hard coat of enamel; if its internal parts are not vitrified, they become ſo extremely hard, as to reſiſt the file; they ſtrike fire with the ham⯑mer, and acquire all the properties of flint: A great degree of heat melts and converts them into real glaſs.
Clay and ſand, therefore, are ſubſtances per⯑fectly analogous, and of the ſame kind. If clay can be condenſed to flint, and even to glaſs, why may not ſand, by reſolution, become clay? Glaſs appears to be the true elementary earth, and all mixed bodies are only glaſs in diſguiſe. Metals, minerals, ſalts, &c. are only a vitrifiable earth: Common ſtone, and other analogous bo⯑dies, teſtaceous and cruſtaceous ſhells, &c. are the only ſubſtances which cannot be vitrified, and which ſeem to form a diſtinct claſs. The former, by the action of fire, may be converted into a homogeneous, hard, and tranſparent ſub⯑ſtance, without any diminution of its weight, and upon which no farther change can be made. The latter, on the contrary, which conſiſt of more active and volatile principles, calcine in the fire, loſe more than a third of their weight, and reſume the form of ſimple earth, without any other change than the diſſolution of their conſtituent parts. If theſe bodies be excepted, which are few in number, and of which the combinations produce few varieties in nature, all other ſubſtances, and particularly clay, may be converted into glaſs, and, conſequently, are [185] only glaſs in a decompoſed ſtate. If the fire quickly vitrifies theſe ſubſtances, glaſs itſelf, whether ſimple, or in the form of ſand or flint, naturally, but by a ſlow and inſenſible progreſs, reſolves into clay.
In countries where flint is the predominant ſtone, the fields are commonly ſtrewed with fragments of it: And, if the place be unculti⯑vated, and if the flints have remained long ex⯑poſed to the air, without being moved, their up⯑per ſurface is always white; but the ſurface next the ground preſerves its natural colour, which is very brown. When theſe flints are broken, the whiteneſs appears to be not ſuperficial only, but penetrates more or leſs into their internal parts, and forms a belt, which in ſome is not very deep, but, in others, occupies nearly the whole ſtone. This white part is ſomewhat granulated, perfectly opaque, as tender as free-ſtone, and adheres to the tongue like the boles. But the other portion of the flint is ſmooth and poliſhed, has neither thread nor grain, and preſerves its o⯑riginal colour, its tranſparancy, and its hardneſs. When this half decompoſed flint is put into a furnace, the white part becomes red like a brick, and the brown part becomes exceedingly white. Why ſhall we conclude, with a famous natura⯑liſt, that flints of this kind are imperfect, and that they are not old enough to have acquired their perfect ſtate? For why ſhould they be [...] imperfect? And why ſhould they be uniformly [186] imperfect on the ſide only that is expoſed to the air? It is, on the contrary, much more probable, that they are changed from their original ſtate, and partly decompoſed, and that they are gra⯑dually reſolving into clay or bole. If this rea⯑ſoning ſhould appear to be unſatisfactory, ex⯑poſe to the air the hardeſt and blackeſt flint, in leſs than a year the colour of its ſurface will be changed; and, if the experiment be farther pro⯑ſecuted, the flint will be found gradually to loſe its hardneſs, its tranſparency, and its other ſpe⯑cific characters, and make daily approaches to the nature of clay.
Sand undergoes the ſame changes as flint. Every grain of ſand may, perhaps, be conſidered as a ſmall flint, and every piece of flint as a col⯑lection of fine ſand cemented together. The firſt example of the decompoſition of ſand is exhibited in that ſhining, but opaque powder, called mica, with which clay and ſlate are al⯑ways impregnated. The quartz, or perfectly tranſparent flints, in decompoſing, produce fat and ſoft talks, ſuch as thoſe of Venice and Ruſ⯑ſia, which are as ductile and vitrifiable as clay; and, it appears, that talk is the mean between glaſs, or tranſparent flint, and clay; but that the groſs and impure flints, in decompoſing, are converted into clay without any intermediate ſtate.
Our made glaſs undergoes the ſame change; when long expoſed to the air, it decompoſes, and, as it were, corrupts. At firſt, it takes on a [187] number of colours, then it exfoliates, and, in handling it, we perceive that many ſhining par⯑ticles fall off. But, when its decompoſition is farther advanced, it bruiſes between the fingers, and is reduced to a very white, talky, and impal⯑pable powder. Art alſo imitates nature in the decompoſition of glaſs and flint. 'Eſt etiam certa methodus, ſolius aquae communis ope, ſilices et arenam in liquorem viſcoſum, eun⯑demque in ſal viride convertendi, et hoc in ole⯑um rubicundum, &c. Solius ignis et aquae ope, ſpeciali experimento, duriſſimos quoſque lapides in mucorem reſolvo, qui diſtillans ſub⯑tilem ſpiritum exhibet, et oleum nullis laudibus praedicabile*.'
Theſe matters ſhall be more fully conſidered when we come to treat of metals. We ſhall here only add, that the different ſtrata of the globe, conſiſt either of materials which may be conſidered as actual vitrifications, or analo⯑gous to glaſs, and poſſeſſing its moſt eſſential qualities; and that it is alſo evident, from the decompoſition of glaſs and of flint, which daily takes place, there reſults a genuine clay; we may therefore conclude, with a high degree of probability, that ſand and clays have originally been the ſcoriae of burnt matter, eſpecially when we join, to the above circumſtances, the proofs a priori which have been employed to ſhow that the earth was formerly in a ſtate of liquefac⯑tion occaſioned by the operation of fire.
I Have often examined quarries, the ſtones of which were full of ſhells; I have ſeen whole hills compoſed of ſhells, and chains of rocks in⯑termixed with ſhells through their whole extent. The quantity of ſhells, and other productions of the ſea, is, in many places, ſo prodigious, that one could with difficulty believe that any more of them exiſted in their natural element. It is from this enormous quantity that no doubt re⯑mains of the earth's having continued for a very long time under the waters of the ſea. The number of ſea-ſhells found in a foſſil or petri⯑fied ſtate is ſo amazing, that, were it not for [189] this circumſtance, we never ſhould have had a proper idea of the ſurpriſing quantities of thoſe animals to which the ocean gives birth. We muſt not, therefore, imagine, like thoſe who talk and reaſon concerning things they never ſaw, that ſhells are only to be found ſcattered here and there by chance, or in ſmall heaps, like thoſe of oiſters thrown from our doors. They appear, on the contrary, in maſſes like moun⯑tains, in banks of 100 or 200 leagues in length; they may often be traced through whole pro⯑vinces, and in maſſes of 50 or 60 feet thick. It is only after having learned theſe facts that a man is entitled to reaſon on this ſubject.
The ſhells of Turenne may ſerve as a ſtriking example. Let us attend to the deſcription given of them by the hiſtorian of the Academy*.
'Though figured ſtones, and even foſſil ſhells found in the bowels of the earth, were remark⯑ed in all ages and nations, they were generally conſidered, even by philoſophers themſelves, as luſus naturae, their production was aſcribed to chance, or ſome unaccountable and fortuitous train of circumſtances; and, of courſe, this wonderful phaenomenon added nothing to the ſtock of knowledge. An ignorant potter in Paris, who knew neither Greek nor Latin, to⯑wards the end of the 16th century, was the firſt man† who ventured, in oppoſition to all the [190] learned, to affirm, that foſſil ſhells were real ſhells originally depoſited, by the ſea, in thoſe places where they were found; that real ani⯑mals, and particularly fiſhes, beſtowed on fi⯑gured ſtones their various forms, &c.; and he boldly defied the whole ſchool of Ariſtotle to invalidate his proofs. His name was Bernard Paliſſy; and he was perhaps the moſt conſpi⯑cuous example of a philoſophical genius, un⯑improved by art or learning. His ſyſtem, however, has lain dormant for near a century, and even his name has almoſt been forgot. At laſt, ſeveral philoſophers revived Paliſſy's ideas; and ſcience has derived great advantage from all the foſſil ſhells and figured ſtones that have appeared in the earth: They are now, perhaps, become too common, and the conſequences drawn from them too incon⯑teſtible.'
'But Reaumur's late obſervations on the ſub⯑ſubject are aſtoniſhing. He diſcovered a maſs below ground of 130,680,000 cubic fathoms of ſhells, either whole or in fragments, with⯑out the leaſt mixture of ſtone, earth, ſand, or other foreign matter. Before this remarkable inſtance, foſſil ſhells never appeared in ſuch enormous quantities, nor without being mixed [191] with other bodies. This prodigious maſs lies in Turenne, more than 36 leagues from the ſea. It is of great ſervice to the peaſants of that province; they uſe the ſhells for marle in ferti⯑lizing their lands, which would otherwiſe be perfectly barren.'
'What the peaſants dig out of the earth, to the depth of eight or nine feet, conſiſts only of fragments of ſhells; but theſe fragments are eaſily recogniſed to be thoſe of real ſhells; for they ſtill retain their original channels or furrows, and have only loſt their luſtre and varniſh, as moſt ſhells do, after having re⯑mained long under ground. The ſmalleſt fragments are only duſt; but we know them to be the duſt of ſhells, becauſe they conſiſt of the very ſame matter with the larger frag⯑ments, and the entire ſhells, which are ſome⯑times found. The ſpecies both of the large fragments and of the entire ſhells, are eaſily diſtinguiſhable. Some of theſe ſpecies belong to the coaſt of Poitou, and others of them to foreign ſhores. This maſs likewiſe furniſhes corals, and other productions of the ſea. Falun is the name by which this matter is diſtinguiſh⯑ed in that province; and it is found, wherever the ground is dug, through an extent of about nine leagues ſquare. The peaſants never dig deeper than about 20 feet; becauſe, ſays Reau⯑mar, they imagine that the expence of labour would exceed the value of the commodity. [192] They might, however, dig deeper. But our calculation of 130,680,000 cubic fathoms pro⯑ceeds upon the ſuppoſition of only 18 feet deep, and 2200 fathoms to the league. Every article, therefore, is undervalued, and this maſs of ſhells muſt greatly exceed the above calculation; if the quantity be only doubled, this wonderful phaenomenon will be greatly augmented.'
'In phyſical facts, there are little circumſtan⯑ces often overlooked by the bulk of mankind, which are, notwithſtanding, of great conſe⯑quence in illuſtrating the ſubject. M. de Reau⯑mur has remarked, that all the fragments of ſhells lie horizontally in the great maſs; from which he concludes, that the fragments were not depoſited at the ſame time with the entire ſhells which originally formed this maſs; becauſe, ſays he, the ſuperior ſhells would, by their weight, have broken the inferior ones, and the fragments, in that caſe, would neceſ⯑ſarily have been diſpoſed in a thouſand differ⯑ent directions. The whole, therefore, whe⯑ther entire or broken, muſt have been gradual⯑ly tranſported thither by the ſea, and, of courſe, their poſition muſt have been horizontal; and, though time alone was ſufficient to break them down, and even to calcine them, it could not vary their original poſition. Their tranſporta⯑tion muſt have been gradual; for, it is impoſ⯑ſible that ſuch an immenſe number of ſhells could be ſuddenly crouded together, and yet [193] preſerve a poſition uniformly horizontal; and their being aſſembled in one place, demon⯑ſtrates this place to have once been the bottom of a gulf or baſon.'
'Though there are many veſtiges of the uni⯑verſal deluge recorded in ſcripture; yet the maſs of ſhells at Turenne could not be an ef⯑fect of this deluge. Perhaps ſuch an amazing maſs is no where to be found, even in the bot⯑tom of the ſea. But, ſuppoſing the deluge to have forced ſuch a quantity from the ocean, they would neceſſarily be carried off with vio⯑lence and precipitation; and, conſequently, could never have been depoſited in the ſame poſition. It behoved them to have been tranſ⯑ported, ſlowly floating in the waves; and, of courſe, their accumulation would require a much longer time than a year.'
'Upon the whole, it is plain, that, either be⯑fore or after the deluge, the earth, at leaſt ſome parts of it, muſt have been in a very different ſituation from what it now appears; that the ſea and land muſt have had a different arrangement; and, that there was formerly a great gulf in the middle of Turenne. The changes recorded in hiſtory, or even in antient fable, are inconſide⯑rable; but they give us ſome idea of what might be produced in a long ſeries of ages. M. de Reaumur conjectures, that Turenne was formerly a gulf of the ſea, and that the ſhells were tranſported by a current. But this is only [194] a mere conjecture, thrown out to ſupply the place of a fact as yet imperfectly known. Be⯑fore any certain concluſion can be drawn, we muſt have geographical charts of all thoſe places where ſhells are found below the ſurface of the earth. To accompliſh this, much time and numberleſs obſervations are requiſite. Science, however, may in time, perhaps, be carried thus far.'
An attention to the following circumſtances will leſſen our ſurpriſe at this great collection of ſhells: 1. Shell-fiſh multiply prodigiouſly, and come to maturity in a very ſhort time. The multitude of individuals in every ſpecies, is a demonſtration of their amazing fertility. In a ſingle day, for example, a maſs of oyſters, of ſeveral fathoms in thickneſs, is often raiſed; the rocks to which they are attached, diminiſh con⯑ſiderably in a ſhort time; and ſome banks are entirely exhauſted. The following year, how⯑ever, furniſhes an equal quantity, and not the ſmalleſt diminution appears. It is even doubted, whether a natural bed of oyſters was ever en⯑tirely exhauſted. 2. The ſubſtance of ſhells is analogous to that of ſtone; they are long pre⯑ſerved when immerſed in ſoft matter; and they eaſily petrify when connected with matter natu⯑rally hard; theſe foſſil ſhells, therefore, and other productions of the ſea found on land, being the ſpoils of many ages, muſt neceſſarily have accu⯑mulated into large maſſes.
[195] We have already remarked the prodigious quantities of ſhells preſerved in marble, lime⯑ſtone, chalk, marle, &c.; that they appear in maſſes like hills or mountains; and that they often compoſe more than one half of the bodies in which they are contained. Sometimes they appear entire, and at other times in fragments, but large enough to enable us to diſtinguiſh their reſpective ſpecies. Here our knowledge of this ſubject, derived from obſervation, ſtops. But I go farther, and maintain, that ſhells are the me⯑dium employed by nature in the formation of moſt ſtones; that chalk, marle, and lime-ſtone, conſiſt entirely of the duſt or fragments of ſhells; and, conſequently, that the quantity of decom⯑poſed ſhells is infinitely greater than that of thoſe which have been preſerved. Theſe poſi⯑tions ſhall be fully eſtabliſhed in the ſection up⯑on minerals; and I ſhall only here exhibit the point of view in which the different ſtrata of the earth ought to be conſidered. The firſt bed, in which nothing of the original ſtructure ap⯑pears, is compoſed of mud depoſited by dews, rains, and ſnow, and of particules of animal and vegetable ſubſtances. The inferior beds of chalk, marle, lime-ſtone, and marble, are com⯑poſed of the ſpoils of ſhells and other ſea-bo⯑dies, mixed occaſionally with entire-ſhells or fragments of them. But clay and vitrifiable ſand are the materials compoſing the internal parts of the globe. Theſe ſubſtances were vitrified [196] at the time the earth aſſumed its figure, which neceſſarily implies, that the whole was then in a melted ſtate. The different ſpecies of granite, flint, free-ſtone in large maſſes, ſlate, and coal, derive their origin from ſand and clay; and are alſo diſpoſed in beds. But tufa and pumice, free-ſtone and flint in ſmall or detached pieces, cryſtals, metals, pyrites, moſt minerals, ſulphurs, &c. are matters, the formation of which is re⯑cent, when compared with that of marble, cal⯑cinable ſtones, chalk, marle, and other ſub⯑ſtances which are diſpoſed in horizontal beds, and contain ſhells, or other relicts of the ocean.
As the terms I have employed may appear obſcure or ambiguous, it is neceſſary to explain them. By clays, I mean not only the white and yellow clays, but likewiſe the blue, the ſoft, the hard, the laminated, &c. which I conſider to be the ſcoriac of glaſs, or the decompoſitions of glaſs. By ſand, I always underſtand vitrifiable ſand; and I comprehend, under this denomina⯑tion, not only the ſine ſand which produces free⯑ſtone, and which I maintain to be the powder of glaſs, or rather of tufa, but alſo that ſand rub⯑bed off free-ſtone, and the ſtill groſſer kind re⯑ſembling ſmall gravel, proceeding from granite and rock-ſtone, and which is brittle, angular, and reddiſh, and generally found in the beds of thoſe rivers which deſcend precipitantly from hills or [197] mountains compoſed of granite or common rock. The river Armanſon, which runs by Sernur in Auxois, where all the ſtones are of common rock, carries down great quantities of this groſs, rough, and brittle ſand; it is of the ſame nature with rock-ſtone, of which it is only ſmall por⯑tions, as calcinable gravels are only particles of free-ſtone. Beſides, rock-ſtone and granite are the ſame ſubſtances; but I have uſed both terms, becauſe they are conſidered by ſome as different ſpecies. The ſame may be remarked of flints and of free-ſtone in large maſſes: Theſe alſo are ſpecies of granite; and I call them flints in large maſſes, becauſe, like calcinable ſtones, they are diſpoſed in beds, and alſo to diſtinguiſh them from flints and free-ſtone in ſmall maſſes, as the round flints and ſand-ſtones which have no con⯑tinuation, or are not found in beds of any ex⯑tent. Theſe are recent productions, and have not the ſame origin as flint and free-ſtone in large maſſes, forming regular and extenſive ſtra⯑ta. Under ſlate I comprehend the blue, the white, the gray, the reddiſh, and all the plated ſtones. Theſe bodies are generally found be⯑low laminated clay, and ſeem to be nothing elſe but clay hardened into thin ſtrata by drying; and this is the reaſon of the many cracks or fiſ⯑ſures remarkable in ſuch ſubſtances. Coal and jet are likewiſe referable to clay, and are found under the laminated clays or ſlate. By tufa I mean not only the common pumice which is [198] full of holes, and has an organized appearance, but all beds of ſtone formed by the ſediments of running waters, all the ſtalactites, incruſtations, and every kind of ſtone that diſſolves by fire. It does not admit of a doubt that all theſe are new ſubſtances, and that they are conſtantly growing. Tufa is only a maſs of ſtony matter, not diſtinguiſhed by regular ſtrata. This mat⯑ter is commonly found in ſmall hollow cylin⯑ders, is regularly ſhaped, formed by rills or drip⯑pings at the foot or upon the declivities of hills, and conſiſting of coats of marle or calcareous earth. The cylindric form is the ſpecific cha⯑racter of this kind of tufa, and it is always ei⯑ther oblique or ſtreight, according to the direc⯑tion of the rills by which it is produced. The ex⯑tent of theſe ſpurious quarries is inconſiderable, and generally proportioned to the height of the mountains which furniſh the materials of their growth. The intervals between the cylinders of the tufa, by the daily addition of freſh ſtony matter, are at laſt filled up, and the whole aſ⯑ſumes a compact and ſolid form; but it never acquires the hardneſs of ſtone, and, for that rea⯑ſon, is denominated by Agricola, marga tofacea fiſtuloſa. In the tufa are often found impreſ⯑ſions of the leaves of ſuch trees and plants as grow in the neighbourhood; land-ſhells, well preſerved, are likewiſe frequently found in the tufa, but never any ſea-ſhells; it is, therefore, a recent production, and ought to be ranked with [199] ſtalactites, incruſtations, &c. All theſe new ſubſtances are a kind of ſpurious ſtones, formed by the waſting of others, but never arrive at the conſiſtence of real petrifaction.
Cryſtal, precious ſtones, every ſtone that has a regular figure, and even flints in ſmall maſſes and conſiſting of concentric coats, whether found in the perpendicular fiſſures of rocks, or elſewhere, are only exudations, or the concre⯑ting juices of flint in large maſſes; they are, therefore, new and ſpurious productions, the genuine ſtalactites of flint or of granite.
Shells are never found in common rock or granite, nor in free-ſtone, although they often appear in vitrifiable ſand, from which free-ſtone derives its origin. This circumſtance ſeems to indicate, that ſand, unleſs when perfectly pure, cannot unite into free-ſtone or granite; and that a mixture of ſhells, or of other heterogeneous bodies, totally prevents it from cementing. I have often examined thoſe ſmall round ſtones, found in beds of ſand that are mixed with ſhells, and never could diſcover in them a ſingle ſhell. Theſe round ſtones are true concretions of free⯑ſtone, formed in thoſe places where the ſand is pure, and not mixed with heterogeneous mat⯑ter; which is the reaſon why no larger maſſes are produced.
We formerly remarked, that, at Amſterdam, which is a very low country, ſea-ſhells were found 100 feet below the ſurface, and at Marly⯑la-Ville, [200] 6 leagues from Paris, at the depth of 75 feet. They have alſo been found in mines below beds of rock of 50, 100, 200, and even of 1000 feet thick, as is apparent in the Alps and Pyernnees, where ſhells and other ſea-bodies are found in the inferior ſtrata of immenſe rocks, that have been cut through in a perpen⯑dicular direction. But to proceed in order: Shells are found in the mountains of Spain, France, and England, in all the marble quarries of Flanders, in the mountains of Gueldres, in all the hills round Paris, in thoſe of Burgundy and Champagne; in a word, in all places where the baſis is not compoſed of free-ſtone or tufa; and, in all theſe places, the ſubſtance of the ſtones conſiſts more of ſhells than of any other matter. By ſhells, I mean not only the re⯑mains of ſhell-fiſh, but likewiſe thoſe of cruſta⯑ceous animals, the briſtles of ſea-hedge-hogs, and all the productions of ſea-inſects, as corals, ma⯑drepores, aſtroites, &c. Any man may be con⯑vinced, by the evidence of his own eyes, that, in moſt marbles and calcinable ſtones, the pro⯑portion of ſea-bodies is ſo great, as to exceed the matter by which they are united.
But, farther, ſea-bodies are found even on the tops of the higheſt mountains of the Alps; for example, on the top of Mount Cenis, in the mountains of Genes, in the Apennines, and in moſt of the ſtone and marble quarries of Italy. They appear in the ſtones of which the moſt [201] antient buildings in Rome are conſtructed, in the mountains of Tirol, in the centre of Italy, on the top of Mount Paterne near Boulogne, in the hills of Pouille, in thoſe of Calabria, in many parts of Germany and of Hungary, and, laſtly, in all the high grounds of Europe*.
In Aſia and Africa, travellers have remarked ſeveral places, for example, 'upon the Caſtra⯑van mountains, above Barute,' ſays Shaw†, 'where there is a curious bed of whitiſh ſtone, but of the ſlate-kind, which contains, in every fleak of it, a great number and variety of fiſh⯑es. Theſe, for the moſt part, lie exceedingly flat and compreſſed, like the foſſil fern plants; yet, at the ſame time, they are ſo well pre⯑ſerved, that the ſmalleſt ſtrokes and lineaments of their fins, ſcales, and other ſuperficial di⯑verſities, are eaſily diſtinguiſhed.' Between Cairo and Suez, and particularly upon all the hills of Barbary, ſays the ſame author, are many petrified ſhells and echini; moſt of them exactly correſpond with the different ſpecies ſtill exiſt⯑ing in the Red Sea. As to Europe, petriſied fiſhes are to be met with in Switzerland, Ger⯑many, the quarry of Oningen, &c.
Foſſil ſhells, ſays M. Bourguet, are to be found in the long chain of mountains ſtretch⯑ing from Portugal to the moſt eaſterly parts of China, in the valleys of Europe, and in all the [202] mountains of Africa and America; and hence, he remarks, we may conclude, that they alſo exiſt in thoſe parts of the globe with which we are ſtill unacquainted.
The iſlands of Europe, of Aſia, and of Ame⯑rica, wherever men have had occaſion to dig, whether in the mountains or in the vallies, furniſh many examples of foſſil ſhells; and this circumſtance demonſtrates, that iſlands are analogous in ſtructure and formation to their neighbouring continents*.
Theſe facts are ſufficient to prove, that foſſil ſhells, petrified fiſhes, and other productions of the ocean, exiſt in great quantities in almoſt every place where proper inveſtigations have been made. 'It is true,' ſays Tancrid Robin⯑ſon, 'that ſea-ſhells are diſperſed occaſionally on the earth by armies, and by the inhabitants of towns and villages. La Loubere relates, in his voyage to Siam, that the monkeys of the Cape of Good Hope perpetually amuſe them⯑ſelves in tranſporting ſhells from the ſhores of the ſea to the tops of the mountains. But this is no ſolution to the queſtion, why theſe ſhells are diſperſed through every climate of the earth, or why they are found in the bowels of the higheſt mountains, and diſpoſed in beds, like thoſe in the bottom of the ocean.'
Upon peruſing an Italian letter, printed at Paris in the year 1746, concerning the changes [203] this globe has undergone, I was aſtoniſhed to find a repetition of Loubere's ſentiments. Pe⯑trified fiſhes, in the opinion of this writer, are always of rare ſpecies, which were rejected from the Roman tables, becauſe they were not e⯑ſteemed to be wholeſome: And as to foſſil ſhells, he ſays, that the pilgrims brought from Syria, in the time of the cruſades, thoſe ſhells peculiar to the Levant, which are now found petrified in France, in Italy, and in other parts of Chriſtendom. Why did he not add, that the monkeys tranſported ſhells to the tops of the higheſt mountains, which never were inhabited by men? This he might have done with great facility, and it would have given an air of credibility to his hypotheſis! How ſhould men, who pretend to philoſophy, differ ſo wide⯑ly in their opinions? It is not ſufficient, it would appear, to find foſſil ſhells in almoſt every part of the earth where pits have been dug, nor to have quoted the teſtimonies of na⯑tural hiſtorians, as they may, according to cer⯑tain ſyſtems, have imagined that ſhells exiſt⯑ed where none were to be found: We ſhall, therefore, to prevent all prejudices of this kind, quote the authority of ſome authors who had no theory to ſupport, and whoſe habits of ob⯑ſervation could only enable them to recogniſe ſhells that were entire, and in the beſt preſerva⯑tion. This teſtimony will, perhaps, have great⯑er authority with men who cannot judge of the [204] facts, nor know the diſtinction between real ſhells and their petrifactions.
Every man may examine with his eyes the banks of ſhells in the hills round Paris, and e⯑ſpecially in the ſtone-quarries, as at Chauſſée near Seve, at Iſly, Paſſy, and other places. A great quantity of lenticular ſtones are to be found at Villers-cotterets; the rocks are almoſt entirely compoſed of them; and they are irre⯑gularly interſperſed with a kind of cement, by which they are united. At Chaumont, the quantity of ſhells is ſo great, that the whole hills, which are pretty high, appear to conſiſt of nothing elſe. The ſame phaenomenon is exhi⯑bited at Courtagnon near Rheims, where there is a bank of ſhells of about four leagues broad, and the length is ſtill more conſiderable. I mention theſe places, becauſe they are famous, and the ſhells ſtrike the eyes of every beholder.
With regard to foreign countries, let us at⯑tend to the remarks of travellers.
'In Syria and Phoenicia, in the neighbour⯑hood particularly of Latikea, the rocks are of a hard chalky ſubſtance, from whence the ad⯑jacent city might borrow the name of the White Promontory. The Nakoura, formerly called the Scala Tyriorum, is of the ſame na⯑ture and complexion; both of them including a great variety of corals, ſhells, and other re⯑mains of the deluge*.'
[205] 'But foſſil ſhells, and other the like teſtimo⯑nies of the deluge, are very rare in the moun⯑tains near Sinai, the original menſtruum, per⯑haps, of theſe marbles being too corroſive to preſerve them. Yet, at Corondel, where the rocks approach nearer to our free-ſtone, I found a few chamae and pectunculi, and a cu⯑rious echinus of the diſcoid kind. The ruins of the ſmall village at Ain-el-Mouſa, and the ſeveral conveyances we have there for water, are all of them full of foſſil ſhells. The old walls of Suez, and the remains that are left us of its harbour, are likewiſe of the ſame ma⯑terials, all of them probably from the ſame quarry. Between Suez and Cairo, likewiſe, and all over the mountains of Lybia, near Egypt, every little riſing ground and hillock diſcovers great quantities of the echini, as well as of the bivalve and turbinated ſhells, moſt of which exactly correſpond with their reſpective families ſtill preſerved in the Red Sea*.'
The moving ſand in the neighbourhood of Raz Sem, in the kingdom of Barca, covers many palm-trees, echini, and other petrifactions. Raz Seme ſignifies the head of a fiſh, and is the name of what is called the petrified village, where it has been alledged, that men and women, with their children, cattle, furniture, &c. may be ſeen converted into ſtone. 'But,' ſays Mr Shaw, 'all this is mere fiction, as I learned not only [206] from Mr Mair, Conſul at Tripoli, who ſent ſe⯑veral people to examine into the fact, but alſo from men of credit and learning who had been on the ſpot.'
Near the Pyramids Mr Shaw diſcovered ſome ſtones that had been hewn by workmen, and were mixed with little round bodies like lentils, and ſome of them reſembled barley half peeled. 'Theſe,' he ſays, 'were ſuppoſed to have been fragments of victuals left by the workmen, and are now petrified. But this account appears to be very improbable,' &c. Theſe lentils and grains of barley are nothing but petrified ſhells, known to every naturaliſt by the name of lentil⯑ſtones.
'Many foſſil ſtones,' ſays Miſſon*, 'are found in the neighbourhood of Maeſtricht, eſpe⯑cially near the village of Zichen or Tichen, and in the mountain called the Huns.'
'In the environs of ſienne, near Certaldo, are many mountains of ſand filled with diffe⯑rent kinds of ſhells. Monte-mario, about a mile from Rome, is alſo full of them. I have remarked them in the Alps, in France, and in other places. Olearius, Steno, Cambden, Speed, and many other writers, have related the ſame phaenomena*.'
'The iſland of Cerigo,' ſays Thevenot‡, 'was called Porphyris by the antients, on ac⯑count [207] of the quantities of porphyry found in it.' Now, porphyry, as obſerved above, is compoſed of the prickles of the echinus, or ſea⯑hedge-hog, united by a very hard ſtony cement.
'Oppoſite to Inchené, a village on the eaſt bank of the Nile, I found petrified plants growing naturally on a piece of ground about two leagues in length, and of an inconſiderable breadth. This is one of the moſt ſingular productions in nature. The plants reſembled the white corals that grow in the Red Sea*.'
'There are ſeveral ſpecies of petrifactions on Mount Libanus, and, among others, flat ſtones which contain the ſkeletons of fiſhes entire, and well preſerved; cheſnuts, and ſmall branches of coral, of the ſame ſpecies with what grows in the Red Sea, are likewiſe found on this mountain†.'
'In mount Carmel,' ſays Shaw, 'we gather a great many hollow ſtones, lined in their inſides with a variety of ſparry matter, which, from ſome diſtant reſemblance, are ſaid to be petri⯑fied olives, melons, peaches, and other fruit. Theſe are commonly beſtowed upon pilgrims, not only as curioſities, but as antidotes againſt ſeveral diſtempers: The olives, which are the lapides Judaici, as they are commonly called, have been always looked upon, when diſſolved in the juice of lemons, as an approved medi⯑cine [208] againſt the ſtone and gravel*.' Theſe lapides Judaici are the points of the echinus.
'M. la Roche, a phyſician, gave me ſome pe⯑trified olives, called lapides Judaici, which grow in great quantities upon the mountains, where are to be found, according to my in⯑formation, other ſtones, which in their inſide contain perfect repreſentations of the natural parts of men and women†.' Theſe are the hyſterolithes.
'In going from Smyrna to Tauris,' ſays Ta⯑vernier, 'when we came to Tocat, the heat was exceſſive; we therefore left the common road to the north of us, and went by the mountains, where there are always ſhade and cool breezes. In many places we found ſnow; and, upon the tops of ſome of theſe mountains, we ſaw ſhells reſembling thoſe upon the ſea-ſhore, which is an extraordinary phaenomenon.'
Let us attend to what Olearius ſays concern⯑ing the petrified ſhells he obſerved in Perſia, and in the rocks where the ſepulchres have been cut near the village Pyrmaraus.
'Three of us aſcended, by mutually aſſiſting each other, the moſt frightful precipices, and at laſt gained the ſummit, where we found four large chambers, with ſeveral niches cut out of the ſolid rock: But what ſtruck us moſt was, to find in this vault, on the top of the [209] mountain, muſcle-ſhells; and in ſome parts they appeared in ſuch quantities, that this whole rock ſeemed to conſiſt of nothing but ſand and ſhells. In returning from Perſia, we perceived ſeveral of theſe ſhelly mountains upon the coaſts of the Caſpian Sea.'
To theſe authorities many others might be added, were I not apprehenſive of tiring thoſe who need no additional proofs on this ſubject, and who have perceived with their eyes, as I have done, the exiſtence of ſhells in all places where they have been ſearched for.
In France, we find not only the ſhells belong⯑ing to our own coaſts, but thoſe which never appeared in our ſeas. Some philoſophers even alledge, that the number of foreign petrified ſhells greatly exceeds thoſe of our own climate. But this opinion ſeems not to be well founded; for, independent of ſuch ſhells as lie in the bot⯑tom of deep water, and are ſeldom brought up by fiſhers, and, of courſe, are regarded by us as foreigners, though they may exiſt in our ſeas, I find, upon compariſon, that more of the petrified ſhells belong to our own ſhores than to any other. For example, all the pectines, moſt cockles, muſcles, oiſters, trumpet-ſhells, ear⯑ſhells, limpets, nautili, ſtars, tubulites, corals, madrepores, &c. which are found ſo univerſally, are really produced in our ſeas: And, though many ſea-bodies appear, which are either foreign or unknown, as the cornu ammonis, the lapi⯑des [210] Judaici, the large ſcrew, the buccinum cal⯑led abajour, &c. yet I am convinced, by repeat⯑ed obſervation, that the number of theſe ſpe⯑cies is inconſiderable, when compared with the ſhells which belong to our own coaſts. Beſide, the madrepores, aſtroites, and all thoſe ſea-bodies formed by inſects, conſtitute the baſis of our marbles and lime-ſtone; for the ſhells, however abundant, make but a ſmall part of theſe ſtones, and many of them are produced in our own ſeas, and particularly in the Mediterranean.
The Red Sea produces corals, madrepores, and ſea-plants, more abundantly than any other. The port of Tor furniſhes an amazing quantity; in calm weather, the quantity exhibited is ſo great, that the bottom of the ſea reſembles a foreſt: Some of the branched madrepores riſe from eight to ten feet high. They are alſo very common in the different parts of the Me⯑diterranean; and are to be found in all gulfs, iſlands, &c. of every temperate climate, where the ſea is not very deep.
Mr Peyſſonel was the firſt who diſcovered that coral, madrepores, &c. were not plants, but that they derived their origin from animals. The truth of this diſcovery was long doubted: Some naturaliſts at firſt rejected it with diſ⯑drain. But it ſoon gained univerſal aſſent; and every man is now ſatisfied, that what was for⯑merly called ſea-plants, are nothing but hives, or rather lodges, formed by inſects for their own [211] habitation. Theſe bodies were originally claſſed with minerals, then with plants, and now they muſt for ever be recogniſed as the genuine ope⯑ration of animals.
Many ſhell fiſh inhabit the deepeſt parts of the ocean, and are never thrown upon the coaſts; authors have, therefore, termed them Pelagiae, to diſtinguiſh them from the other kinds which they call Littorales. It is probable that the cornu ammonis, and ſome other ſpecies, found only in a petrified ſtate, belong to the former, and that they have been impregnated with ſtony matter in the very places where they are diſcovered. It is alſo probable, that the ſpecies of ſome animals have been extinguiſhed, and that theſe ſhells may be ranked among this number. The ex⯑traordinary foſſil bones found in Siberia, in Ca⯑nada, in Ireland, and ſeveral other places, ſeem to confirm this conjecture; for no animal has hitherto been diſcovered to whom bones of ſuch enormous ſize could poſſibly belong.
Foſſil ſhells, ſays Woodward, are found from the top to the bottom of quarries, in pits, and in the deepeſt mines of Hungary: And we are in⯑formed by Mr Ray, that they are found in the rocks on the ſhores of Calda, and in Pembroke⯑ſhire, at the depth of 200 fathoms*.
Shells not only appear in a petrified ſtate at great depths, and on the tops of the higheſt mountains, but they are alſo found in their na⯑tural [212] condition, having the colour, luſtre, and lightneſs of ſea-ſhells; ſo that, to be fully ſatis⯑fied on this ſubject, nothing farther is requiſite than to compare them with the ſhells found on the ſhores of the ſea. The ſlighteſt examina⯑tion will convince us, that petrified and foſſil ſhells are preciſely the ſame with thoſe of the ocean; for they are marked with the ſame fur⯑rows and articulations, however minute; and, in the gloſſopetri and other teeth of fiſhes, which are ſometimes found adhering to the jaw-bone, it is obvious to remark, that the teeth are worn and poliſhed at the extremities, and that they have been uſed by the living animals.
Foſſil ſhells are almoſt every where to be met with; and, of thoſe of the ſame ſpecies, ſome are ſmall, others large, ſome young, others old, ſome entire, others imperfect; and ſometimes young ones appear adhering to the old.
The ſhell-fiſh called Purpura, has a long tongue, the extremity of which is ſo ſharp and oſſeous, that it pierces the ſhells of other fiſhes, in order to extract nouriſhment from them, Shells pierced in this manner are often found in the bowels of the earth; which is an incon⯑teſtible proof that they were formerly inhabited by living fiſhes, and that they exiſted in the ſame places with the purpura*.
The obeliſks of St Peter's at Rome, accor⯑ding to John of Latran, were ſaid to have been [213] brought from the Egyptian pyramids: They conſiſt of a red granite, whiche, as formerly re⯑marked, contains no ſhells. But the antient marbles of Africa and Egypt, and the porphyry ſaid to have been brought from Solomon's temple, and the palaces of the Egyptian kings, and employed in ſeveral of the Roman buildings, are full of ſhells. Red porphyry is compoſed of an infinite number of the prickles of that ſpecies of echinus called a ſea-cheſnut; they are placed very near each other, and form the white points of the porphyry. Each of theſe points have a black ſpeck in the middle, which is the ſection of the longitudinal tube of the prickle of the echinus. At Ficin in Burgun⯑dy, three leagues from Dijon, there is a red ſtone ſo ſimilar to porphyry, that it differs only in denſity, not being harder than marble: It is en⯑tirely compoſed of the points or prickles of the echini, and the ſtratum of it is conſiderable both in thickneſs and extent. Many excellent pieces of workmanſhip are made of it in this province, and particularly the ſteps that lead to the pedeſtal of the equeſtrian ſtatue of Louis le Grand at Dijon. This ſpecies of ſtone is alſo found in Montbard in Burgundy; it is ſofter than marble; but it contains ſtill more prickles of the echini, and a ſmaller proportion of red matter. Thus the antient porphyry of Egypt, and the por⯑phyry of Burgundy, differ only in the de⯑gree▪ of hardneſs, and in the quantity of [214] prickles or points of the echinus contained in them.
With regard to what is called green porphyry, I imagine it to be rather a granite than a por⯑phyry. It is not, like the red porphyry, com⯑poſed of the prickles of the echinus; and its ſubſtance reſembles more that of common gra⯑nite. The antient walls of Volatera in Tuſcany, have been built of ſtones in which are many ſhells, and this wall was built 2500 years ago*. Moſt marbles, porphyries, and other ſtones em⯑ployed in the buildings of the antients, contain ſhells, and other productions of the ocean, in the ſame manner as ſome of our modern marbles. Hence we conclude with ſafety, that, indepen⯑dent of the teſtimony of holy writ, the earth, before the deluge, was compoſed of the ſame materials that it is at preſent.
Upon the whole, it is apparent, that petrified ſhells are found in Europe, in Aſia, in Africa, and in every place where proper reſearches have been made. They are alſo found in America, in the Braſils, for example, in Tucumama, in Terra Magellanica, and in ſuch vaſt quantities in the Antilles, that what the inhabitants call lime, which lies immediately below the ſoil, is nothing but a congeries of ſhells, corals, madrepores, aſtroites, and other ſea-bodies. Theſe incon⯑teſtible facts would have led me to conclude, that petrified ſhells, and other productions of the [215] ocean, were to be found through the whole continent of America, and eſpecially in the moun⯑tains, as is affirmed by Woodward. But M. de la Condamine, who lived ſeveral years in Peru, aſſures me, that he was never able to diſcover any of them in the Cordeliers, although he had diligently ſearched for them. This phaeno⯑menon would indeed be ſingular, and would lead to concluſions ſtill more ſingular. But, I con⯑feſs, the teſtimony of this celebrated obſerver notwithſtanding, I am ſtrongly inclined to be⯑lieve that there is, in the mountains of Peru, as well as every where elſe, petrified ſhells and other ſea-bodies, although they have not yet been diſ⯑covered. In matters that depend on teſtimony, the poſitive evidence of two witneſſes is a com⯑pleat proof; but the evidence of ten thouſand witneſſes, who only declare in the negative, that they never obſerved a particular appearance, give riſe to nothing more than a ſlight doubt. Thus reaſon, joined to the force of a general analogy, obliges me to perſiſt in believing that foſſil ſhells will ſtill be found in the mountains of Peru, e⯑ſpecially if they be ſearched for in the ſides, and not on the very ſummits.
The tops of high mountains are generally compoſed of granite, free-ſtone, and other vitri⯑fiable materials, which never contain ſhells. Theſe matters were all formed out of beds of ſand, when they were covered by the ſea. But, when the waters left the mountains, they would [216] carry off the ſand, and other light bodies, into the plains, and leave nothing on their tops but thoſe beds of rock which had been formed below the ſtratum of ſand. At two, three, or four hun⯑dred fathom below the ſummit of theſe moun⯑tains, we often find marbles and other calcinable matters, diſpoſed in parallel beds, and contain⯑ing ſhells and other ſea-bodies. Hence, if M. de la Condamine examined only the moſt ele⯑vated places, which conſiſt of granite, of free⯑ſtone, or of vitrifiable ſand, it is not ſurpriſing that he did not find foſſil ſhells. But he ought to have explored the lower parts of the Corde⯑liers, and he would unqueſtionably have diſco⯑vered beds of marble, earth, &c. mixed with ſhells; for ſuch beds have been found in every part of the world that has undergone a proper examination.
But, ſuppoſing it to be a fact, that there are no productions of the ocean in the mountains of Peru, nothing could be concluded from it that would affect our theory. Some parts of the globe, and particularly places of ſuch elevation as the Cordeliers, might never have been cover⯑ed with the ſea. Theſe mountains, however, would be an ample field for curious obſervation. They would not, in that caſe, conſiſt of parallel beds. Their materials would be very different from all others: They would have no perpen⯑dicular fiſſures: The ſtructure of the ſtones and rocks would have no reſemblance to thoſe of [217] other countries: Laſtly, Theſe mountains would exhibit the antient ſtructure of the earth before it was changed by the motion of the waters; they would diſcover the primitive ſtate of the globe, its original form, the natural arrangement and connection of its parts. But this notion is ſupported by too ſlender a foundation; and it is more conſonant to the rules of philoſophy to believe that foſſil ſhells exiſt in the mountains of Peru, in the ſame manner as they exiſt every where elſe.
With regard to the poſition of ſhells in beds of earth or of ſtone, let us attend to the follow⯑ing paſſage of Woodward: 'All the ſhells that are found in numberleſs ſtrata of earth, and rocks, in the higheſt mountains, and in the moſt profound quarries and mines, in flint, cornelian, agate, &c. and in maſſes of ſulphur, marcaſites, and other mineral and metallic bo⯑dies, are filled with the ſame ſubſtances that compoſe the ſtrata in which they are included, and never with any heterogeneous matter;' p. 206. &c.—'We now find in the ſand⯑ſtone of all countries (the ſpecific gravity of the ſeveral ſorts whereof is very little different, being generally to water as 2½ or 2 9/10 to 1) only thoſe conchae, pectines, cochleae, and other ſhells that are nearly of the ſame gra⯑vity, viz. 2½ or 2 5/ [...] to 1. But theſe are ordi⯑narily found encloſed in it in prodigious num⯑bers; whereas, of oiſter-ſhells, (which are in [218] gravity but as about 2⅓ to 1) of echini, (which are but as 2, or 2⅛ to 1) or the other lighter kinds of ſhells, ſcarce one ever appears therein. On the contrary, in chalk (which is lighter than ſtone, being but as about 2 1/10 to 1) there are only found echini, and the other lighter ſorts of ſhells;' p. 32. 33.
It muſt here be remarked, that what Wood⯑ward ſays with reſpect to ſpecific gravity, is not univerſally true; for ſhells of different ſpecific gravities are often found in the ſame matters; ſhells of cockles, of oiſters, and of echini, for example, are found in the ſame bed of ſtones or of earth. In the cabinet of the French King, there is a cockle petrified in a cornelian, and echini petrified in an agate. Hence the difference in the ſpecific gravity of ſhells has had leſs in⯑fluence upon their poſition in the ſtrata of the earth than Woodward would have us to believe. The reaſon why the ſhells of the echini, and others of a light texture, abound ſo much in chalk, is owing to this circumſtance, that chalk itſelf is only decompoſed ſhells; thoſe of the echini being lighter and thinner than others, would be moſt eaſily reduced to powder or chalk; and hence beds of chalk could only exiſt in thoſe places where were formerly collected by the ſea great quantities of light ſhells, the de⯑ſtruction of which would form that chalk in which we ſtill find ſhells that have reſiſted the [219] operation of time, either in an entire ſtate, or in fragments ſufficient to diſcover their ſpecies.
This ſubject ſhall be treated more fully in the article of Minerals; I ſhall here only obſerve, that Woodward's expreſſions are often too ge⯑neral. He appears to aſſert, that ſhells are found as frequently, and in as great abundance, in flints, cornelians, calcedonii, ores, and ſul⯑phur, as in other matters. But the fact is, that ſhells are a very rare phaenomenon in vitrifiable or purely inflammable ſubſtances; and, in chalk, marle, and marbles, the quantity of them is ſo prodigious, that it is impoſſible to affirm that the lighter and heavier ſhells are uniformly found in ſtrata correſponding to their ſpecific gravities, though, in general, this may be the caſe oftener than otherwiſe. They are all impregnated with the bodies in which they are immerſed, whe⯑ther in the horizontal beds, or in the perpendi⯑cular fiſſures, becauſe the whole has been effec⯑ted by the operation of water, though at differ⯑ent times and in different manners. Thoſe found in the horizontal beds of ſtone, marble, &c. have been tranſported and depoſited by the waves of the ſea; and thoſe found in flints, cornelians, and other ſubſtances peculiar to the perpendicular fiſſures, were formed by rills of water impregnated with lapidific or metallic ſubſtances. In both caſes, the matter that fills the ſhells has been in the ſtate of a fine impal⯑pable [220] powder; becauſe every pore of them is compleatly filled, and the moulds of them are as exact as the impreſſions of a ſeal upon wax.
It is, therefore, apparent, that, in ſtone, marble, &c. there are multitudes of ſhells ſo entire, and ſo well preſerved, that they may be compared with thoſe in our cabinets, or upon the ſhores of the ſea.
'There being, I ſay, beſides theſe, ſuch vaſt multitudes of ſhells contained in ſtone, &c. which are entire, fair, and abſolutely free from any ſuch mineral contagion; which are to be matched by others at this day found upon our ſhores, and which do not differ in any reſpect from them; being of the ſame ſize that thoſe are of, and the ſame ſhape preciſely; of the ſame ſubſtance and texture, as conſiſting of the ſame peculiar matter, and this conſtituted and diſpoſed in the ſame manner as is that of their reſpective fellow-kinds at ſea; the tendency of the fibres and ſtriae the ſame; the compo⯑ſition of the lamellae, conſtituted by theſe fibres, alike in both; the ſame veſtigia of ten⯑dons (by means whereof the animal is faſten⯑ed and joined to the ſhell) in each; the ſame papillae; the ſame futures, and every thing elſe, whether within or without the ſhell, in its cavity, or upon its convexity, in the ſub⯑ſtance, or upon the ſurface of it. Beſides, theſe foſſil, ſhells are attended with the ordi⯑nary [221] accidents of the marine ones, ex. gr. they ſometimes grow to one another, the leſſer ſhells being fixed to the larger: They have balani, tu⯑buli vermiculares, pearls, and the like, ſtill actu⯑ally growing upon them. And, which is very conſiderable, they are moſt exactly of the ſame ſpecific gravity with their fellow-kinds now upon the ſhores. Nay farther, they anſwer all chymical trials in like manner as the ſea⯑ſhells do; their parts, when diſſolved, have the ſame appearance to view, the ſame ſmell and taſte*.'
I have often obſerved, with aſtoniſhment, whole mountains, chains of rocks, and extenſive quarries, ſo full of ſhells, and other ſea-bodies, that there was hardly ſpace left for the matters in which they are depoſited.
I have ſeen ſome arable fields ſo full of pe⯑trified cockles, that they might be picked up by a blind man, others entirely covered with cornu ammonis, and others with cardites; and the more this ſubject is inquired into, we ſhall be the more thoroughly convinced, that the number of pe⯑trifactions is infinite, and that it was abſolutely impoſſible that all the animals which inhabited theſe ſhells could exiſt at the ſame time.
I have farther remarked, that the ſtones of thoſe arable lands which abound with petrified ſhells in an entire form, well preſerved, and de⯑tached from all other matter, are frittered down [222] by froſt, which deſtroys ſtones, but has little ef⯑fect upon petrified ſhells.
Theſe immenſe quantities of petrified ſea⯑bodies, found in ſo many different places and ſi⯑tuations, prove, that they could not be tranſport⯑ed and depoſited by the waters of the deluge; for the greateſt part of them, inſtead of being found in the bowels of the earth, and in ſolid marble at the depth of ſeven or eight hundred feet, behoved to have remained on the ſurface.
In all quarries, petrified ſhells form part of the internal ſtructure of the ſtone, the ſurface of which is often covered with ſtalactites, a matter much leſs antient than the ſtone that contains the ſhells. Another proof that theſe ſhells could not be derived from the deluge is, that the bones, horns, claws, &c. of land-ani⯑mals are ſeldom found in a petrified ſtate, and are never incorporated in marble, or other hard ſtones; whereas, if theſe effects had been pro⯑duced by the deluge, the remains of land-ani⯑mals would have been found in marbles, as well as thoſe of fiſhes.
To alledge, that the earth was entirely diſſol⯑ved at the time of the deluge, is a mere gratui⯑tous ſuppſition, which required a ſecond miracle in order to give water the power of an univer⯑ſal diſſolvent. Beſides, it infers an evident con⯑tradiction; for, if water was then an univerſal menſtruum, how could ſhells have been pre⯑ſerved in the entire ſtate in which we find them? [223] This is an evident demonſtration, that no ſuch diſſolution took place, and that the parallel ſtrata were not formed in an inſtant, but were gradu⯑ally produced by ſucceſſive ſediments; for, it is apparent to every obſerver, that the diſpoſition of all the materials compoſing the earth has been occaſioned by the operation of water. The on⯑ly queſtion, therefore, that remains, is, whether this arrangement of parts was produced all at once, or in a ſucceſſion of time? Now, it has already been ſhown, that it could not poſſibly happen at one time; becauſe the materials are not diſpoſed according to their ſpecific gravities, and becauſe they never ſuffered a general diſſo⯑lution. This arrangement, therefore, muſt have originated from ſucceſſive ſediments. Any other cauſe, or particular revolution, would have gi⯑ven riſe to an arrangement totally different. Be⯑ſides, particular revolutions, or accidental cauſes, could never have produced a uniform diſpoſi⯑tion of horizontal and parallel ſtrata throughout the whole globe.
Let us attend to what the hiſtorian of the Academy* has ſaid upon this ſubject.
'The many marks of extenſive inundations, and the manner in which mountains muſt be conceived to have been produced, demonſtrate, that the ſurface of this earth has ſuffered great revolutions. However deep we penetrate in⯑to [224] to the globe, we diſcover nothing but ruins, bodies of different kinds amaſſed and incor⯑porated without any order or apparent deſign. If there be any regularity in the ſtructure of the earth, it lies too deep for our reſearches; we muſt, therefore, confine ourſelves to the ruins of the external cruſt, which will be ſuf⯑ficent to occupy the attention of philoſophers.'
'M. de Juſſieu diſcovered, in the neighbour⯑hood of St Chaumont, a great quantity of ſlaty or laminated ſtones, every lamina of which was marked with the impreſſion of a ſtem, leaf, or other portion of ſome plant. In the impreſſions of leaves, they were uniform⯑ly extended, as if they had been ſtreached in the ſtones by the hand; a clear demonſtration that they had been tranſported by water, which always keeps leaves in that poſition: Their ſituations were various, and ſometimes they lay acroſs each other.'
'It is natural to imagine, that a leaf depoſi⯑ted by water upon ſoft mud, and then cover⯑ed by a ſimilar layer of mud, would impreſs upon the lowermoſt layer the figure of its one ſide, and upon the uppermoſt the figure of its oppoſite ſide; and, after theſe layers hardened and petrified, that they would each bear an impreſſion of a different ſide of the leaf. But this ſuppoſition, however natural, does not take place: The two laminae of ſtone uni⯑formly [225] formly bear the impreſſion of the ſame ſide of the leaf, the one in alto, the other in baſs⯑relief. For this obſervation, with regard to the figured ſtones of St Chaumont, we are in⯑debted to M. de Juſſieu; but we leave the ex⯑plication of it to himſelf, and ſhall proceed to remarks of a more general and intereſting na⯑ture.'
'All the impreſſions on the ſtones of Saint Chaumont are of foreign plants, which are not to be found in any part of France; they are natives either of the Eaſt Indies, or of the warmer climates of America. Moſt of them belong to the capillary tribes, and they are ge⯑nerally particular ſpecies of ferns, the cloſe texture of which enables them both to make deep impreſſions, and to remain long in a ſtate of preſervation. M. Leibnitz was aſtoniſhed to find the impreſſions of the leaves of a few Eaſt India plants upon ſome ſtones in Ger⯑many: In the example under conſideration, the wonder is greatly augmented; for, by ſome unaccountable deſtination of nature, it would appear, in all the ſtones of Saint Chau⯑mont, not a ſingle impreſſion of a native plant is to be found.'
'From the number of foſſil ſhells in the mountains and quarries exhibited in this coun⯑try, as well as in many others, it is apparent, that it muſt have formerly been covered with [226] the ſea. But how could the American or In⯑dian oceans come hither?'
'To ſolve this and other ſurpriſing phaeno⯑mena, we may ſuppoſe, with much probabi⯑lity, that the ſea originally covered the whole globe. But this ſuppoſition will not anſwer; becauſe no terreſtrial plants could then exiſt: The plants of one country, therefore, could only be tranſported to another by great inun⯑dations.'
'M. de Juſſieu imagines, that, as the bed of the ſea is always riſing higher by means of the mud and ſand inceſſantly carried into it by the rivers, the ſea, at firſt confined by natural dikes, might at laſt ſurmount them, and ſpread over the land to great diſtances; or, which would produce the ſame effect, the dikes might in time be rendered ſo thin, by the conſtant ope⯑ration of the water, that they would at laſt give way. Soon after the formation of the earth, when nothing had aſſumed a regular or ſettled form, ſudden and prodigious revo⯑lutions might then be produced, of which we have now no examples, becauſe every thing is in ſuch a fixed and permanent ſtate, that only ſlow and inconſiderable changes can take place: It is for this reaſon that we find a dif⯑ficulty in crediting revolutions more ſudden and tremendous.'
'By ſome of theſe great revolutions the Weſt [227] or Eaſt Indian Oceans might have been poured in upon Europe: In their journey, they would tear up foreign plants, carry them off floating on the waves, and gently depoſite them in ſhallow places, from which the waters would ſoon evaporate.'
THOUGH the inequalities upon the ſurface of the earth may be conſidered as a defor⯑mity in its figure, they are abſolutely neceſſary to vegetation and animal life. To be convinced of this, we need only conſider what would be the condition of the earth, were its ſurface per⯑fectly ſmooth and regular. Inſtead of thoſe beautiful hills which furniſh abundance of wa⯑ter for ſupporting the verdure of the earth, in⯑ſtead of thoſe richly garniſhed fields, where plants and animals find an eaſy and comforta⯑ble ſubſiſtence, a dreary ocean would cover the whole globe, and the earth, deprived of all its [229] valuable and alluring qualities, would be an obſcure, abandoned planet, ſuited only for the habitation of fiſhes.
But, independent of moral conſiderations, which ſeldom ought to be employed in natural philoſophy, the ſurface muſt, from a phyſical neceſſity, have been irregular; for, ſuppoſing it to have been originally ſmooth and level, the motion of the waters, ſubterraneous fires, the winds, and other external cauſes, would neceſ⯑ſarily produce, in time, irregularities ſimilar to thoſe which we now behold.
Next to the elevation of mountains, the depths of the ocean form the greateſt inequalities. This depth is exceedingly diverſified, even at great diſtances from land. In ſome places the ſea is ſaid to be a league in depth; but that is a rare phaenomenon; and the moſt common depths are from 60 to 150 fathoms. Gulfs and branches of the ocean that run in upon the land, are ſtill leſs deep; and ſtraits are generally the moſt ſhallow places.
Depths are commonly ſounded by a piece of lead, 30 or 40 pounds weight, fixed to a ſmall rope. This method anſwers well enough for or⯑dinary depths, but is liable to error when the depth is very great; for the cord being ſpecifi⯑cally lighter than water, after much of it has been wound down, the weight of the lead and that of the cord become nearly equal to their bulks of water; then the lead deſcends no more, [230] but runs off in an oblique line, and floats at the ſame depth. Hence, in ſounding great depths, an iron chain, or ſome body heavier than water, ſhould be employed. It is for want of atten⯑tion to this circumſtance, that ſome navigators have been led to maintain, that the ſea, in ma⯑ny places, has no bottom.
In general, the depths in open ſeas augment or diminiſh in a pretty regular manner, being commonly deeper the farther from land. But to this remark there are many exceptions; for there are places in the middle of the ſea, as at the Abrolhos in the Atlantic, where large ſhelves appear; and there are, in other places, vaſt ſand-banks, well known to the mariners who ſail to the Eaſt Indies.
Along coaſts, the depths are likewiſe very irre⯑gular. However, it may be laid down as a cer⯑tain rule, that the depth is always proportioned to the height of the coaſt: The ſame obſervation applies to rivers.
It is eaſy to meaſure the height of mountains, either geometrically or by the barometer. This inſtrument determines the height of a mountain pretty exactly, eſpecially in countries where its variation is not conſiderable, as at Peru and o⯑ther equatorial climates. By one or other of theſe methods, the height of moſt mountains has already been aſcertained; for example, it has been found, that the higheſt mountains of Swit⯑zerland exceed Canigau, the moſt elevated of [231] the Pyrennees, 1600 fathoms*. Theſe moun⯑tains appear to be the higheſt in Europe, ſince they give riſe to a great number of rivers which run into different and very diſtant ſeas, as the Po, which empties itſelf in the Adriatic, the Rhine, which loſes itſelf in the ſands of Hol⯑land, the Rhone, which falls into the Mediter⯑ranean, and the Danube, which runs into the Black Sea. Theſe four rivers, the mouths of which are ſo diſtant, derive part of their waters from Saint Godard and the neighbouring moun⯑tains; a clear proof that this place is the moſt ele⯑vated part of Europe.
Mount Taurus, Imaus, Caucaſus, and the mountains of Japan, are higher than any in Eu⯑rope. The mountains of Africa, as the great Atlas, and the mountains of the Moon, are at leaſt equally high with thoſe of Aſia; and the higheſt of all are thoſe of South America, and eſpecially of Peru, which are 3000 fathoms above the level of the ſea. In general, the tropical mountains are more elevated than thoſe of the temperate zones, and the latter are higher than thoſe nearer the poles. Thus, the nearer the Equator, the greater are the ſuperficial inequali⯑ties, which, though conſiderable with regard to us, are nothing when eſtimated in relation to the whole globe. A difference of 3000 fathoms in 3000 leagues diameter, is but a fathom to a league, or a foot to 2200 feet, and, upon a globe of 2½ feet, [232] would not make the 16th part of a French line. Hence this earth, which to us appears to be tra⯑verſed and interſected by mountains of an enor⯑mous height, and by ſeas of a dreadful depth, is, in relation to its ſize, but ſlightly furrowed with inequalities ſo inconſiderable, that they can⯑not make any variation upon its general figure.
The mountains, in continents, form continued chains; but, in iſlands, they are more interrupt⯑ed, generally riſe in the form of a cone, or py⯑ramid, and are diſtinguiſhed by the name of peaks. The Peak of Teneriffe, in the Iſland of Fer, is one of the higheſt mountains in the earth; it is nearly a league and a half perpendicular a⯑bove the level of the ſea. The Peak of St George in one of the Azores, and the Peak of Adam, in the Iſland of Ceylon, are likewiſe ex⯑ceedingly high. Theſe peaks are compoſed of rocks, piled above each other; and all of them throw out, from their ſummits, fire, aſhes, bitu⯑men, minerals, and ſtones. Some iſlands, as St Helena, Aſcenſion Iſle, and moſt of the Canaries and Azores, are only the tops or points of moun⯑tains. It is alſo worthy of remark, that the middle of moſt iſlands, promontories, and capes, is the moſt elevated, and that they are generally divided into two parts, by chains of mountains which run in the direction of their greateſt length: In Scotland, for example, the Grampian mountains (Grans-bain) extend from eaſt to weſt, and divide the Iſland of Great Britain into [233] two parts: The ſame thing takes place in Su⯑matra, the Lucca Iſlands, Borneo, Celebes, Cuba, St Domingo, the peninſulas of Corea and Ma⯑laya, &c. Italy is alſo longitudinally traverſed by the Appennines.
Mountains, as mentioned above, are of differ⯑ent heights; the hills are loweſt; then follow the mountains of an ordinary height, which are ſucceeded by a third range ſtill higher. All theſe are commonly covered with trees and plants; but neither of them furniſh ſprings excepting at their bottoms. In the laſt and higheſt range, we find nothing but ſand, looſe ſtones, flints, and rocks, the tops of which often reach above the clouds. Preciſely at the foot of theſe rocks, are little plains, or hollows, which collect rains and ſnow, and form thoſe ponds, moraſſes, or fountains, from which the rivers derive their ſources*.
The figure of mountains is likewiſe very dif⯑ferent. Some conſiſt of long chains of nearly an equal height; others are interſected by deep vallies; the contours of ſome mountains are pretty uniform; thoſe of others are moſt irre⯑gular, and ſometimes a detached little mountain appears in the middle of a plain or valley. There are alſo two kinds of plains; ſome occupy the low grounds, and others appear in the moun⯑tains. The former are generally divided by ſome large river; but the latter, though their [234] extent be conſiderable, are dry, or furniſhed with only a ſmall rill. The plains in the mountains are often exceedingly high, always of difficult acceſs, and form one country above another, as in Auvergne, Savoy, and other elevated pro⯑vinces. The ſoil of them is firm, and produces plenty of herbs and odoriferous plants, which renders them the fineſt paſture-grounds in the world.
The tops of high mountains are compoſed of rocks of different elevations, which, when view⯑ed at a diſtance, make them reſemble the waves of the ſea*. This is not the only reaſon for our affirming that mountains were formed by the motions of the ſea; I only mention it, be⯑cauſe it correſponds with every other phaeno⯑menon. But the following facts put this point beyond all controverſy: The foſſil ſhells, and other ſea-bodies, every where found in ſuch profuſion, that they could not poſſibly be tranſ⯑ported from the ſea, in its preſent ſtate, into continents ſo diſtant, and depoſited at ſuch great depths in the bowels of the mountains: The univerſal paralleliſm of the different ſtrata, an effect which could only be produced by water, and the compoſition even of the moſt denſe of them, as thoſe of ſtone and marble, which clear⯑ly evinces, that, before their formation, they had been reduced into a fine powder, and precipi⯑tated to the bottom in the form of ſediments: [235] The exactneſs with which the foſſil ſhells are moulded in the matters in which they are found: The cavities of foſſil ſhells, which are uniform⯑ly filled with the ſame ſubſtances that contain them: The correſponding angles of hills and mountains, which nothing could effect but the currents of the ocean: The equality in the heights of oppoſite hills, and the different ſtrata uniformly appearing at the ſame levels: And, laſtly, the direction of mountains, the chains of which extend longitudinally, like the waves of the ſea.
With regard to the depths or hollows on the ſurface of the earth, thoſe of the ocean are un⯑queſtionably the greateſt. But, as theſe are hid from human view, and can only be diſcovered by ſounding, we ſhall confine ourſelves to thoſe which appear on the dry land, ſuch as deep val⯑lies, precipices found between rocks, abyſſes that preſent themſelves in high mountains, as the abyſs of Mount Ararat, the precipices of the Alps, the vallies of the Pyrennees, &c. Theſe depths are a natural conſequence of the elevation of mountains; they receive the water and earth carried down from the high grounds; their ſoil is generally fertile; and they are full of in⯑habitants. The precipices among rocks are of⯑ten occaſioned by a ſudden ſinking of one ſide, the baſe, which generally inclines more one way than another, being looſened by the action of the air, and of froſt, or by the violence of [236] torrents. But abyſſes, or thoſe enormous pre⯑cipices that appear on the tops of ſome moun⯑tains, and, to the bottom of which, though their circumference be a mile and a half, or three miles round, it is impoſſible to deſcend, have been formed by the operation of fire. They have been the furnaces of antient volcano's, the matter of which has been exhauſted by explo⯑ſions and the long action of fires, which are now extinguiſhed from the want of combuſtible matter. Of this kind is the abyſs of Mount Ararat, deſcribed by Tournefort. It is ſurround⯑ed with rocks that are black and burned. The abyſſes of Aetna and of Veſuvius will have the ſame appearance after their inflammable mate⯑rials are exhauſted.
In Plot's hiſtory of the country of Stafford in England, there is an account of a kind of gulf, which was ſounded by a rop of 2600 feet, with⯑out finding either watter or bottom, the rop being too ſhort*.
The greateſt cavities, and the deepeſt mines, are generally in the mountains, and they ſeldom deſcend to the level of the plains; and we diſ⯑cover by them the internal ſtructure of the mountain only, not that of the globe itſelf.
Beſides, theſe depths are not very conſiderable. Mr Ray affirms, that the deepeſt mines exceed not half a mile. The mine of Cotteberg, which, in the time of Agricola, was eſteemed to be the [237] deepeſt in the world, was only 2500 feet of perpendicular depth. There are, indeed, holes in particular places, as that mentioned by Plot, or Pool's hole in the county of Derby, the depth of which is probably very great: But none of them bear any ſenſible proportion to the thick⯑neſs of the globe.
If the kings of Egypt, in place of erecting pyramids as monuments of their vanity and riches, had expended equal ſums in making pro⯑found excavations into the bowels of the earth, to the depth of perhaps a league, they might have diſcovered ſubſtances which would have recompenſed their labour; they would at leaſt have extended the knowledge of the earth's in⯑ternal ſtructure, which might have been pro⯑ductive of much utility.
But, let us return to the mountains. The higheſt of them lie between the tropics; and the nearer we approach to the equator, the greater are the inequalities on the earth's ſur⯑face. A ſhort enumeration of mountains and iſlands will be ſufficient to eſtabliſh this point.
In America, the Cordeliers, which are the higheſt mountains in the world, lie preciſely under the equator, and they extend on both ſides a conſiderable way beyond the Tropic circles.
The higheſt mountains of the Moon, of Mo⯑nomotapa, and the great and little Atlas, in Africa, lie either under or very near the equa⯑tor.
[238] In Aſia, Mount Caucaſus, the chain of which, under different names, runs into China, and, through this whole extent, lies nearer the equa⯑tor than the poles.
In Europe, the Pyrennees, the Alps, and the mountains of Greece, which form one chain, are ſtill leſs diſtant from the equator than the pole.
Theſe chains of mountains, of which we have given an enumeration, are higher, and of greater extent, both in length and in breadth, than thoſe of more northern countries. With regard to their direction, the Alps form a con⯑tinued chain which runs acroſs the whole Con⯑tinent from Spain to China. They commence on the ſea-coaſt of Galicia, join the Pyrennees, traverſe France, by Vivares and Auvergne, run through Italy, and ſtretch into Germany, above Dalmatia, until they reach Macedonia; from thence they join the mountains of Armenia, the Caucaſus, the Taurus, the Imaus, and at laſt terminate on the coaſt of Tartary. Mount Atlas, in the ſame manner, traverſes the whole Continent of Africa, from the kingdom of Fez to the ſtraits of the Red Sea. The mountains of the Moon have likewiſe the ſame direction.
But the mountains of America have an oppo⯑ſite direction. The vaſt chains of Cordeliers, and other mountains, run more from ſouth to north than from eaſt to weſt.
[239] What we have now remarked concerning the greateſt elevations of the land, applies equally to the greateſt depths of the ſea. The moſt exten⯑ſive and deepeſt ſeas lie nearer the equator than the poles: From theſe united obſervations, the truth of our general poſition, that the greateſt inequalities of the globe are to be found in the equatorial regions, is ſufficiently eſtabliſhed. Theſe irregularities on the ſurface of the earth give riſe to a number of curious phaenomena. Between the Indus and the Ganges, for example, there is a large peninſula, through the middle of which runs a chain of high mountains, called the Gate, which extends, from north to ſouth, from the extremity of Mount Caucaſus to Cape Comorin; one ſide of this peninſula forms the coaſt of Malabar, the other that of Coromandel. On the Malabar ſide, between the chain of mountains and the ſea, the ſeaſon of ſummer is from September to April; and, during theſe months, the ſky is ſerene, and no rain falls. But, on the Coromandel coaſt, which lies on the other ſide of the mountains, this very period is their winter, and the rains fall abundantly. This reverſe of ſummer and winter happens in ſome places no farther diſtant than 20 leagues; ſo that, by croſſing the mountains, a man has it in his power to change ſeaſons. The ſame thing, it is ſaid, takes place at Cape Razalgat in Arabia, and even in Jamaica, which is divided from eaſt to weſt by a chain of mountains; on the ſouth [240] ſide of theſe mountains, the plantations enjoy the warmth of ſummer, while thoſe on the north ſuffer all the rigours of winter. Peru, which is ſituated under the line, and extends about 1000 leagues towards the ſouth, is divided into three long and narrow portions, called by the inha⯑bitants Lanos, Sierras, and Andes. The Lanos, which are the plains, extend along the coaſt of the South Sea; the Sierras are hills interſperſed with vallies; and the Andes are the famous Cor⯑deliers, the higheſt mountains in the world. The Lanos are about 10 leagues broad; the Sierras, in many places, 20 leagues; and the Andes nearly the ſame, though ſome parts of them are more, and others leſs broad. The breadth of theſe diviſions is from eaſt to weſt, and their length from ſouth to north. This part of the world exhibits the following remarkable ap⯑pearances: 1ſt, Along the whole coaſt of the Lanos, a ſouth-weſt wind almoſt conſtantly blows, which is contrary to the ordinary direc⯑tion of the wind in the Torrid Zone. 2d, In the Lanos, it never rains or thunders, though they have plentiful dews. 3d, It rains almoſt continually in the Andes. 4th, In the Sierras, which lie between the Lanos and the Andes, it rains from September to April.
It was long thought, that all high mountains run from weſt to eaſt, till the contrary direction was diſcovered in America. But M. Bourguet was the firſt who remarked the ſurpriſing re⯑gularity [241] in the ſtructure of theſe great maſſes. After paſſing the Alps thirty times in fourteen different places, the Apennines twice, and ma⯑king ſeveral tours in the neighbourhood of theſe mountains, and of Mount Jura, he found, that the contours of all mountains have a near re⯑ſemblance to the works in regular fortifications. When the direction of a mountain is from weſt to eaſt, all its projections, or advances, ſtretch to the ſouth and north. This amazing regula⯑rity is ſo remarkable in the vallies, that one is apt to imagine that he is walking in a covered way. If, for example, a man travels in a val⯑ley from north to ſouth, he perceives that the mountain which lies to the right hand makes projections to the eaſt, and that the projections of the oppoſite mountain regard the weſt, in ſuch a manner, that the prominent and concave angles, on each ſide, alternately correſpond with one another. When the vallies are large, the angles of the mountains are leſs acute, becauſe they are more diſtant from each other, and the declivity is not ſo rapid or ſteep. Theſe angles are not perceptible in plains, excepting when we ſtation ourſelves on the banks of the rivers, which generally occupy the middle of them, and whoſe natural windings correſpond to the moſt advanced angles or projections of the mountains. It is aſtoniſhing that ſuch an ob⯑vious fact ſhould have remained ſo long unno⯑ticed; for, it is apparent, that, in vallies lined [242] with oppoſite mountains, when the declivity of one of the mountains is leſs rapid than that of the other, the courſe of the rivers is not in the middle, but neareſt to the ſteepeſt mountain*.
Theſe general obſervations might be confirm⯑ed by a multitude of facts. The moutains of Switzerland, for example, are ſteeper on the ſouth ſide than on the north, and on the weſt ſide than on the eaſt. This appearance is ob⯑vious in Mount Gemmi, Mount Briſa, and in almoſt all the other mountains in this country, the higheſt of which are thoſe which ſeparate Valleſia, and the Griſons of Savoy, from Pied⯑mont and Tirol. Theſe countries are, indeed, only a continuation of the ſame mountains, the chain of which extends to the Mediterranean; and the Pyrennees are only a continuation of that vaſt mountain, which commences in Upper Valleſia, whoſe branches ſtretch far to the weſt and ſouth, and preſerve, throughout that whole extent, a great height; but, on the north and eaſt ſides, they gradually ſink into plains, as ap⯑pears in thoſe great countries which are traver⯑ſed by the Rhine and Danube before they finiſh their courſe, while the Rhone deſcends with ra⯑pidity to the ſouth, and empties itſelf in the Mediterranean. The ſame obſervation is exem⯑plified in the mountains of England and of Norway. But the moſt perfect example is af⯑forded [243] by the mountains of Chili and Peru. The Cordeliers are exceedingly ſteep on the weſt ſide; but they have a gradual declivity to the eaſt, and terminate in vaſt plains, that are watered by the greateſt rivers in the world*.
M. Bourguet, to whom we are indebted for the diſcovery of the correſpondence between the angles of mountains, calls this diſcovery the Key to the Theory of the Earth. However, he appears not to have perceived its whole impor⯑tance; for, in his treatiſe on this ſubject, he gives only the ſkeleton of an hypothetical ſyſtem, in which moſt of his concluſions are either falſe or uncertain. The theory that we have deliver⯑ed reſts upon four principal facts, the truth of which, after examining the proofs that ſupport them, cannot admit of a doubt: The firſt is, That the earth, to very conſiderable depths, is every where compoſed of parallel ſtrata of dif⯑ferent matters, which were formerly in a fluid or ſoft ſtate: The ſecond, That the ſea has, for many ages, covered the whole earth which we now inhabit: The third, That the tides, and other motions of the waters, produce inequali⯑ties in the bottom of the ſea: And the fourth, That the figure, and correſponding direction of mountains, have originated from currents in the ocean.
After peruſing the proofs contained in the ſubſequent articles, the reader will be enabled to [244] determine whether I am right in maintaining, that theſe facts, when firmly eſtabliſhed, will likewiſe aſcertain the genuine theory of the earth. What has been remarked concerning the formation of mountains needs no farther expli⯑cation. But, as it may be objected, that I have not accounted for the formation of peaks, or pointed mountains, nor for ſome other particu⯑lar facts, I ſhall add ſuch obſervations as have occurred upon this ſubject.
I have endeavoured to form a diſtinct and general idea of the manner in which the mate⯑rials compoſing this earth are arranged, and have reduced the whole to two claſſes. The firſt includes all the matters that are diſpoſed in horizontal, or regularly inclined beds or ſtrata; and the ſecond comprehends all thoſe matters which appear in detached maſſes, in ridges, or in veins, either perpendicular, or irregularly in⯑clined. In the firſt claſs I rank ſands, clays, granites, flints, and free-ſtones in large maſſes, pit-coal, ſlates, and likewiſe marles, chalk, cal⯑cinable ſtones, marbles, &c. In the ſecond, I in⯑clude metals, minerals, cryſtals, precious ſtones, and flints in detached and ſmall maſſes. Under theſe two claſſes, all the known materials of the earth are comprehended. Thoſe of the firſt claſs owe their origin to ſediments tranſported and depoſited by the waters of the ſea, and ought to be diſtinguiſhed into thoſe that are calcinable by the application of fire, and thoſe that melt, [245] and are convertible into glaſs. The matters comprehended under the ſecond claſs are all vitrifiable, with the exception of thoſe called in⯑flammable, or which totally conſume in the fire.
There are, in the firſt claſs, two diſtinct ſpe⯑cies of ſand; the one, which abounds more than any other matter in the globe, is vitrifiable, or rather conſiſts of fragments of real glaſs: The other, which is leſs in quantity, is calci⯑nable, and ought to be regarded as the duſt of ſtone, and as differing from gravel only by the groſſneſs of its grains. In general, vitrifiable ſand lies in beds; but they are frequently inter⯑rupted by maſſes of free-ſtone, of granite, and of flint; and ſometimes theſe ſubſtances appear in banks of a conſiderable extent.
Sea-ſhells are ſeldom found in vitrifiable bo⯑dies; and even thoſe which appear in them are not diſpoſed in beds, but ſcattered, as it were, by chance: I never, for example, found any in free-ſtone. This ſtone, which abounds in cer⯑tain places, is nothing but ſand united by a ce⯑ment. It never appears but in countries where vitrifiable ſand is frequent; and the quarries of it are generally in pointed hills, in ſandy lands, or in interrupted eminences. Theſe quarries may be wrought on all ſides; and, when they appear in large beds, they are more diſtant from each other than thoſe of marble or calcinable ſtones. Blocks of free-ſtone may be cut of all dimenſions; and, though it be difficult to work, [246] its hardneſs is inconſiderable; for it is eaſily re⯑duced to ſand by friction, excepting the black points or nails ſometimes found in it, which are ſo hard as to reſiſt the beſt files. Common rock⯑ſtone, which I conſider as a ſpecies of granite, is vitrifiable, and of a ſimilar nature with free⯑ſtone; it is only harder, and more firmly ce⯑mented. It has likewiſe ſeveral denſe points, which cut the ſhoes of travellers on mountai⯑nous grounds. It alſo contains a great number of talky ſpangles; and the whole is ſo hard as not to be worked without great labour.
After narrowly examining theſe hard points found in free-ſtone and granite, I diſcovered that they conſiſt of metallic matter, which has been melted and calcined by a ſtrong fire, and that they have a perfect reſemblance to certain ſub⯑ſtances thrown out of volcano's, of which I have ſeen vaſt quantities in Italy. They are called by the inhabitants Schiarri. They are black heavy maſſes, upon which neither fire, water, nor the file, can make any impreſſion. It is very different from lava, the latter being a ſpe⯑cies of glaſs; but the former ſeems to partake more of metal than of glaſs. The points in free⯑ſtone and granite have a great reſemblance to this matter, whcih is a farther proof that thoſe ſubſtances have formerly been liquified by fire.
On the tops of ſome high mountains, blocks of granite appear in great quantities. Their poſitions are ſo irregular, that they ſeem to have [247] been thrown together by accident; and we would be apt to imagine that they had tumbled down from ſome neighbouring height, if the places where they are found were not higher than any neighbouring ground. But their vi⯑trifiable nature, and their angular and ſquare figures, like thoſe of free-ſtone rocks, diſcover theſe ſubſtances to have an uncommon origin. Thus, in large ſtrata of vitrifiable ſand, we find blocks of free-ſtone and granite, the figure and ſituation of which follow not exactly the hori⯑zontal poſition of ſtrata. The rains have gra⯑dually brought down from the hills and moun⯑tains the ſand with which theſe blocks were ori⯑ginally covered, by furrowing and cutting into thoſe intervals that appear between the yokes or nuclei in free-ſtone, in the ſame manner as the hills of Fountainbleau are interſected. Every point of a hill reſembles a nucleus in free-ſtone quarries, and all the intervals have been ſcooped out by the rains, and the ſand they originally contained has been carried down to the vallies. In the ſame manner, the angular blocks of gra⯑nite on the tops of high mountains were for⯑merly covered and ſurrounded with vitrifiable ſand, which being gradually carried off by the rains, left the blocks in the poſition in which they happened to be formed. Theſe blocks are generally pointed at the top, and augment in thickneſs towards their baſes; one block often reſts upon another, that upon a third, and ſo on, [248] leaving irregular intervals between them: And as, in the courſe of time, the ſand which cover⯑ed the blocks, and filled the intervals, was waſh⯑ed down by the rains, there would nothing re⯑main on the tops of high mountains but pointed piles of irregular blocks; and hence the origin of peaks, or mountains ending in ſharp points.
For, let it be ſuppoſed, as may eaſily be pro⯑ved by the ſea-bodies found in the Alps, that this chain of mountains was formerly covered by the ocean, and that a thick bed of vitrifiable ſand was depoſited upon their tops, which redu⯑ced the whole chain to a level country. This bed of ſand would neceſſary give riſe to large blocks of granite, of free-ſtone, of flint, and of other bodies, whoſe conſiſtence and figure origi⯑nate from ſand, nearly in the ſame manner as ſalts cryſtallize. Theſe blocks, after the ſand which covered them, and filled their interſtices, was carried down to the plains by rains, torrents, &c. would maintain their original ſtations, re⯑main bare on the tops of the mountains, and conſtitute all thoſe peaks or pointed eminences ſo frequently to be met with. To the ſame origin muſt be aſcribed thoſe high detached rocks which are found in China and other countries, as in Ireland, where they are diſtinguiſhed by the name of Devil's ſtones, and the formation of which, as well as of peaked mountains, has hi⯑therto appeared ſo difficult to explain. The explication, however, which I have given, is ſo [249] natural, that it generally occurs to every perſon who examines theſe objects; and, on this occa⯑ſion, I will ſet down a paſſage from father Tar⯑tre. 'From Yanchuin-yen we arrived at Ho⯑tcheou; upon the road we remarked a ſin⯑gular phaenomenon, namely, rocks of a ſur⯑priſing height, reſembling ſquare towers, in the midſt of vaſt plains. I cannot account for this appearance, unleſs I be allowed to ſuppoſe theſe rocks to have formerly conſtituted a part of mountains, and that the earth, ſand, and other looſe parts, had been gradually waſhed away by the rains, and left the rocks bare on all ſides. What fortifies this conjecture is, that we ſaw ſome of them, the baſes of which were ſtill ſurrounded with earth to a conſiderable heighth*.'
The tops of the higheſt mountains, often for 200 or 300 fathoms, conſiſt of rocks of granite, free-ſtone, and other hard and vitrifiable ſub⯑ſtances: Below this, we frequently meet with quarries of marble, or hard calcinable ſtone, full of foſſil ſhells; as may be ſeen at the great Chartreuſe in Dauphiny, and upon Mount Cenis; where the ſtones and marbles that contain ſhells are ſituated ſome hundreds of fathoms below the points or peaks of high mountains, though theſe beds of ſtone and marble be more than 1000 fathoms above the level of the ſea. Thus thoſe mountains that have peaks or points, generally [250] conſiſt of vitrifiable rocks; and thoſe, the ſum⯑mits of which are flat, contain, for the moſt part, marbles, and hard ſtones full of ſea-bodies. The ſame remark holds with regard to hills; for thoſe compoſed of granite or free-ſtone, are ge⯑nerally interſected with points, eminences, ca⯑vities, and ſmall vallies. But thoſe compoſed of calcinable ſtone, are nearly of an equal height, and are only interrupted by larger and more re⯑gular vallies, with correſponding angles; and they are crowned with rocks, uniform and level in their poſition.
Though theſe two ſpecies of mountains ſeem to be very different, their figures have been pro⯑duced by the ſame cauſe, as has already been ſhown: Only, it may be remarked, that the cal⯑cinable ſtones have ſuffered no change ſince the original formation of the horizontal ſtrata. But the vitrifiable ſands may have been changed and interrupted by the ſubſequent production of rocks and angular blocks that takes place in ſand⯑beds. Both ſpecies have fiſſures; thoſe in cal⯑cinable rocks are almoſt always perpendicular; but thoſe of granite and free-ſtone are ſomewhat more irregular in their direction. It is in theſe fiſſures that metals, minerals, cryſtals, ſulphur, and all the ſubſtances of our ſecond claſs, are found. Below the fiſſures, the waters aſſemble, penetrate the earth, and give riſe to the veins of water that every where appear under the ſur⯑face.
I HAVE already remarked, that, in general, the greateſt mountains occupy the middle of continents; that thoſe of a ſmaller kind divide iſlands, peninſula's, and promontories; that, in the Old Continent, the direction of the greateſt chains of mountains is from weſt to eaſt; and that thoſe which run to the north or ſouth, are only branches of the principal chains. It will appear, on examination, that the greateſt rivers have the ſame direction, and few of them follow the courſe of the branches of mountains. To be convinced of this fact, we have only to run our eye over a common globe; and, beginning with Spain, we ſhall find that the Vigo, the [252] Douro, the Tagus, and the Guadiana, run from eaſt to weſt, and the Ebro from weſt to eaſt; and that there is not a river of any conſideration which runs from ſouth to north, or from north to ſouth, although Spain be almoſt entirely en⯑vironed by the ſea on the northern and ſouthern parts. This remark concerning the rivers of Spain demonſtrates, that the direction of the mountains is from weſt to eaſt; that the ſou⯑thern provinces near the Straits are more ele⯑vated than the coaſts of Portugal; that, in the northern parts, the mountains of Galicia, the Aſturias, &c. are only a continuation of the Pyrennees; and that this elevation of the coun⯑try, both in the ſouth and north, is the cauſe which prevents the rivers from running to the ſea in theſe directions.
In examining the map of France, it is appa⯑rent, that the Rhone is the only river which runs from north to ſouth; and even near one half of its courſe, from the mountains to Lyons, is from eaſt to weſt: But the direction of all the great rivers, as the Loire, the Charente, the Ga⯑ronne, and even the Seine, is from eaſt to weſt.
The ſame obſervation holds with regard to Germany. The Rhine, like the Rhone, has the greateſt part of its courſe from ſouth to north: But the other large rivers, as the Danube, the Drave, and all the rivers which fall into them, run from weſt to eaſt, and empty themſelves in the Black Sea.
[253] The Black Sea, which ſhould rather be re⯑garded as a large lake, is, from eaſt to weſt, near⯑ly three times as long as from ſouth to north; and conſequently its direction is ſimilar to that of the rivers. The ſame remark is applicable to the Mediterranean, which is nearly ſix times longer from eaſt to weſt than from north to ſouth.
The Caſpian, it muſt be acknowledged, ac⯑cording to the chart made by order of the Czar Peter I. extends more from north to ſouth, than from eaſt to weſt. But the antient charts re⯑preſented it as nearly round, or rather as ex⯑tending more from eaſt to weſt than in the oppoſite direction. If, however, the lake Aral be conſidered as a part of the Caſpian, from which it is ſeparated only by a ſandy plain, the greateſt extent of this ſea will ſtill be from weſt to eaſt.
The courſe of the Euphrates, of the Perſic gulf, and of almoſt all the rivers of China, is likewiſe from weſt to eaſt. The rivers of the interior parts of Africa obſerve the ſame direc⯑tion, running either from weſt to eaſt, or from eaſt to weſt. The Nile, and the rivers of Bar⯑bary, are the only ones that run from ſouth to north. There are, it is true, large rivers in A⯑ſia, as the Don, the Wolga, &c. which partly run from north to ſouth: But they only ob⯑ſerve this direction in order to fall into the Black [254] and Caſpian ſeas, which are lakes in the interior parts of the country.
We may, therefore, lay it down as a fact, that, in general, the rivers and mediterranean waters of Europe, Aſia, and Africa, run or ſtretch more from eaſt to weſt than from north to ſouth. This is a natural conſequence of the parallel direction of the different chains of mountains. Beſides, the whole continent of Europe and of Aſia is broader from eaſt to weſt than from north to ſouth: For the direction of mountains may be conſidered in two points of view; in a long and narrow continent, like that of South America, which contains only one principal chain of mountains, extending from ſouth to north, the rivers, not being reſtrained by any parallel chain, muſt run in channels per⯑pendicular to the range of theſe mountains, that is, either from eaſt to weſt, or from weſt to eaſt; and this, in fact, is the direction of all the great rivers in America. But though, both in the Old and New Continent, the great rivers run in the ſame direction, this effect is produ⯑ced by different cauſes. The rivers, in the Old Continent, run from eaſt to weſt, becauſe they are confined by many parallel chains of moun⯑tains that ſtretch from weſt to eaſt; but thoſe of America obſerve the ſame direction, becauſe there is only one cahin of mountains ſtretching from ſouth to north.
[255] The rivers generally occupy the middle of the vallies, or the loweſt ground between two oppoſite hills: If the two hills have nearly an equal declivity, the river runs nearly in the mid⯑dle between them, whether the intermediate valley be broad or narrow. If, on the contra⯑ry, the declivity of one of the hills be greater than that of the other, the river will not occupy the middle of the valley, but will approach to the ſteepeſt hill, in proportion to the ſuperiority of its declivity. In this caſe, the middle of the valley is not the loweſt ground between the two hills, but lies much nearer the ſteepeſt of them; and conſequently the river muſt occupy this ſpace. This obſervation holds univerſally where⯑ever the difference in declivity is any ways re⯑markable; and the rivers never recede from the ſteepeſt hills, unleſs, in their courſe, they meet with other hills of equal declivity. In proceſs of time, however, the declivity of the ſteepeſt hill is diminiſhed by the rains, the melting of ſnow, &c. The ſteeper any hill is, it loſes great⯑er quantities of earth, ſand, and gravel, by the operation of rains, and theſe ſubſtances are car⯑ried down into the plain with a proportionably greater rapidity, and, of courſe, force the ri⯑ver to change its channel, or, in other words, to retire into a lower part of the valley. To this it may be added, that, as all rivers occaſionally ſwell, and overflow their banks, they carry off mud and ſand, which they depoſite in different [256] parts of the valley; and, as ſand and gravel are often accumulated in the channels themſelves, theſe circumſtances make the waters overflow and alter the direction of their courſe. Nothing, accordingly, is more common, than to find in vallies many old channels in which the river has formerly run, eſpecially when it is rapid, ſub⯑ject to frequent inundations, and carries down great quantities of ſand and mud.
In plains, and extenſive valleys, watered by large rivers, the channels of the rivers are com⯑monly the loweſt parts: But the ſurface of the water in the river is ſometimes higher than the adjacent ground. When a river, for inſtance, begins to overflow, it ſoon covers a conſiderable part of the plain; but the banks remain longeſt uncovered by the water. This plainly demon⯑ſtrates the banks to be higher than the neigh⯑bouring ground; and from the banks, to a cer⯑tain part of the plain, there is a ſmall declivity or ſlope. When, therefore, the water riſes to the margin of the banks, it muſt be higher than the plain. This elevation of the ground on the banks of rivers is occaſioned by mud and ſand being depoſited in the time of inundations. The water, during great ſwells, is always ex⯑ceedingly foul and muddy: When it begins to overflow, it runs ſlowly over the banks, and, by depoſiting the mud and ſand, it gradually puri⯑fies as it advances into the plain: Thus, all the mud, and other ſubſtances, that are not carried [257] down by the current, are depoſited upon the banks, and gradually elevate them above the reſt of the plain.
Rivers are always wideſt at their mouths, and turn gradually narrower towards their ſources: But it is more worthy of remark, that, in the in⯑terior parts of a country, and at great diſtances from the ſea, their courſe is ſtraight, and the frequency of their windings increaſes propor⯑tionably as they approach to their termination. I have been informed by M. Fabry, who per⯑formed many journeys in the weſtern parts of North America, that travellers, and even the ſa⯑vages, form pretty accurate computations of their diſtance from the ſea, by obſerving the courſes of the rivers. If a river ran ſtraight for 15 or 20 leagues, they knew themſelves to be a great way from the coaſt; but, if the ſinuoſities were frequent, they concluded that the ſea was not very diſtant. M. Fabry, when travelling through unknown and uninhabited regions, de⯑rived much advantage from this obſervation. Near the ſides of great rivers, the regorging of the water is likewiſe leſs apparent the farther from the ſea, which furniſhes another medium of judging concerning the diſtance: And, as the ſinuoſities multiply the nearer rivers approach to their mouths, it is not ſurpriſing that ſome of them ſhould yield to the preſſure of the water, and give riſe to ſeveral branches, or diviſions, before they reach the ſea.
[258] The motion of the water in rivers is very dif⯑ferent from the repreſentation given of it by mathematicians. The ſurface, taken from bank to bank, is not level; but the middle of the ſtream is either higher or lower, according to circumſtances, than the water at the ſides. When a river ſwells ſuddenly by the melting of ſnow, or any other cauſe, its rapidity increaſes; and, if its courſe be ſtraight, the middle of the ſtream, where the current is greateſt, riſes and forms a ſenſible convexity. This elevation is ſometimes very conſiderable. M. Hupeau, who meaſured this difference of level between the ſides and the ſtream of the Aveiron, found it to be three feet. This effect muſt always be produced when the rapidity of the current is great; for the quickneſs of the motion, by diminiſhing, or partly preventing the action of gravity, allows not to the water, in the middle of the ſtream, time ſufficient to bring it to a level with that on the ſides, and, therefore, it remains higher. On the other hand, near the mouths, though the current be very rapid, the water near the ſides is commonly more elevated than that of the middle: The river, in this ſituation, has a con⯑cave form, the loweſt point of which is the middle of the ſtream. This always happens as far as the influence of the tides is perceptible, which, in large rivers, extends ſometimes to 100 or 200 leagues from the ſea. It is likewiſe a fact well known, that the ſtreams of rivers con⯑tinue [259] their motion a conſiderable way through the waters of the ſea. In this caſe, the water of the river has two oppoſite motions. The middle, or current, precipitates itſelf towards the ſea; but the action of the tide produces a counter current, or regorging, which elevates the water on the ſides, while that in the middle deſcends; and, as all the water muſt be carried down by the current, that on the ſides conſtantly deſcends towards the middle of the ſtream, with a quick⯑neſs proportioned to the elevation it receives from the regorging of the tide.
There are two ſpecies of regorging, or dam⯑ming up, in rivers: The firſt is that juſt now deſcribed, and is occaſioned by the action of the ride, which not only oppoſes the natural deſcent of the water, but even communicates to it a contrary motion or current: The other is pro⯑duced by an inactive cauſe, as a projection of the land, an iſland, &c. Though this kind of regorging gives not riſe to any extraordinary counter current, it often ſenſibly retards the pro⯑greſs of ſmall boats, and produces what is called dead water, which obſerves not the natural courſe of the river, but turns about in ſuch a manner as greatly obſtructs the progreſs of veſſels. Theſe dead waters are ſenſibly felt in paſſing through the arches of a bridge, eſpecially if the river be rapid. The celerity with which water runs, when the height or preſſure is the ſame, increaſes in proportion as the diameter of the canal, [260] through which it paſſes, is diminiſhed. The ce⯑lerity of a river, therefore, in paſſing through a bridge, increaſes in the inverſe proportion of the width of the whole arches, to the total width of the river. This increaſe of celerity, in paſſing through the arch of a bridge, is ſo conſiderable, that it puſhes the water from the ſtream towards the banks, from which it is reflected, and ſome⯑times forms violent eddies or whirlpools. In paſſing under the bridge of St Eſprit, the mari⯑ners are obliged ſcrupulouſly to keep the ſtream, even after leaving the bridge; for, if they al⯑lowed the boat to decline either to the right or left, it would be driven with violence againſt the banks, or, at leaſt, would be forced into the whirling or dead waters, from which they would find ſome difficulty of eſcaping. When the eddy is conſiderable, it forms a ſmall gulf with a cylindrical void in the middle of it, round which the water turns with rapidity. This cy⯑lindrical cavity is an effect of the centrifugal force, which makes the water endeavour to fly off from the center of the whirlpool.
When a great ſwell of the river is about to happen, the water-men perceive a particular motion, which they call a moving at the bottom; that is, when the water at the bottom moves with an unuſual velocity, which, according to them, always indicates the approach of a ſudden ſwell. The motion and weight of the ſuperior waters, though not yet arrived, fail not to act upon the [261] waters in the inferior parts of the river, and to communicate motion to them: For a river, in ſome reſpects, muſt be conſidered as a column of water contained in a tube, and its channel as a long canal, in which every motion muſt be com⯑municated from one end of it to the other. Now, independent of the motion of the ſuperior wa⯑ters, their weight alone may increaſe the celeri⯑ty of the river, and perhaps make it move quick⯑eſt at the bottom; for, it is well known, that, when ſeveral boats are all at once puſhed into a river, they increaſe the motion of the water be⯑low, and retard that of the ſuperior water.
The celerity of running waters is not in ex⯑act proportion to the declivity of their channels. A river with a uniform declivity, and double to that of another, ought not, it would appear, to run with more than a double celerity: But its celerity is much more quick, being ſometimes triple, ſometimes quadruple, &c. The celerity depeends more upon the quantity of water, and the weight of the ſuperior waters, than upon the degree of deſcent. In digging the bed of a river or drain, it is unneceſſary to make the de⯑ſcent uniform through its whole extent. A quick motion is more eaſily produced by ma⯑king the declivity much greater at the ſource then at the mouth, where, like the beds of na⯑tural rivers, it is almoſt imperceptible, and yet they preſerve their celerity, which is more or leſs, according to the quantity they contain; for, [262] in great rivers, even where the ground is level, the water ſtill runs, not only with the velocity originally acquired, but with the accumulated velocity produced by the action and weight of the ſuperior waters*. To make this matter ſtill more plain, let us ſuppoſe the Seine from Pont⯑neuf to Pont-royal to be perfectly level, and to be ten feet deep; let us alſo ſuppoſe the bed of the river below Pont-royal and above Pont-neuf, to be ſuddenly dried up; the waters, in this caſe, would run both up and down the channel, till their equilibrium was perfectly reſtored. This effect is produced entirely by the weight of the water, which never allows it to remain at reſt till its particles are equally preſſed on all ſides, and its ſurface reduced to a perfect level. The weight of water, therefore, contributes greatly to increaſe the celerity of its motion. This is the reaſon why the greateſt celerity in a current of water is neither at the bottom nor at the ſur⯑face, but nearly in the middle, which is preſſed both by the column above, and by the reaction from the bottom. But, what is ſtill more, when a river acquires a great celerity, it will not only preſerve it, though running through a level country, but even ſurmount heights, without [263] ſpreading much to a ſide, or, at leaſt, without producing an inundation of any moment.
One would be apt to imagine, that bridges, and other obſtacles erected in rivers, would create a conſiderable diminution of celerity in their whole courſe. But the difference is very ſmall. The water, upon meeting with any obſtacle, riſes, in order to ſurmount it; and the increaſe of ce⯑lerity communicated by its fall, nearly compen⯑ſates the retardation occaſioned by the obſtacle. Thus, ſinuoſities, projections from the land, and iſlands, create but a ſmall variation on the total celerity of a river's courſe. The moſt conſide⯑rable alterations are produced by the greater or leſſer quantities of water; when the quantity is ſmall, a river runs ſlow, when great, it runs with rapidity.
If rivers were always equally full, to enlarge their channels would be the beſt method of di⯑miniſhing their rapidity, and to contain them within their banks. But, as almoſt all rivers riſe and fall, it is more neceſſary, for this latter purpoſe, to narrow their channels; for ſmall waters, with large channels, generally ſcoop out winding beds in the middle; and, when they ſwell, they follow the direction of theſe particu⯑lar beds, and, by ſtriking with violence againſt the banks, often do much injury to mills and other works. Theſe bad effects might be pre⯑vented, by digging gulfs in the earth at conve⯑nient diſtances. To accompliſh this, a part of [264] one of the banks ſhould be cut through, and the earth removed for a conſiderable ſpace. Theſe ſmall gulfs ſhould be made in the obtuſe angles of the river; for the water, in turning, would run into them; and, of courſe, its celerity would be diminiſhed. This method might be uſeful in preventing the fall of bridges in places where ſufficient barriers cannot be erected to reſiſt the weight of the water.
The manner in which inundations are pro⯑duced, merits particular attention. When a ri⯑ver ſwells, its celerity uniformly increaſes, till it begins to overflow the banks: From that mo⯑ment its rapidity is checked, which is the reaſon why inundations always continue ſeveral days; for, though the quantity of water ſhould be diminiſhed after the commencement of the in⯑undation, it would, notwithſtanding, continue to overflow; becauſe this circumſtance depends more on the celerity than on the quantity of water. If it were otherwiſe, rivers would often overflow their banks for an hour or two, and then retire to their channels, which never does happen. An inundation, on the contrary, al⯑ways laſts ſome days, ſuppoſing the rains have [...], and leſs water runs in the river; becauſe the overflowing of waters diminiſhes their ecle⯑rity; and, conſequently, although the ſame quantity of water arrives not in the ſame time as formerly, the effect is the ſame as if a larger quantity had been brought down. It may like⯑wiſe [265] here be remarked, that, if a high wind blows contrary to the current of the river, the inundation will be increaſed by this occaſional cauſe, which diminiſhes the celerity of the wa⯑ter; but, if the wind blows in the direction of the current, the inundation will be leſs, and re⯑tire more quickly.
'The inundation of the Nile,' ſays M. Gran⯑ger, 'has long been a ſubject of diſcuſſion a⯑mong the learned. Moſt of them have conſi⯑dered it as a ſingular and wonderful phaenome⯑non, though nothing be more natural or more common; for it takes place in every country, as well as in Egypt. The inundation of the Nile is occaſioned by the rains which fall in Aethiopia and Abyſſinia; but the north wind may be regarded as the principal cauſe of it: 1. Becauſe the north wind drives the clouds that contain this rain into Abyſſinia: 2. Be⯑cauſe it prevents the water from running out of the mouths of the river in any great quan⯑tity, by damming up the ſtream. The great effect of this wind may be remarked every ſeaſon; for, when it changes from north, the Nile loſes more water in one day than in four.'
Inundations are generally greateſt in the ſu⯑perior parts of rivers; becauſe, as formerly ob⯑ſerved, the velocity of a river uniformly in⯑creaſes till it empties itſelf in the ocean. Father Coſtelli, a ſenſible writer on this ſubject, re⯑marks, that the banks, raiſed for the purpoſe of [266] keeping the Po from overflowing, gradually di⯑miniſh in height, as the river approaches to the ſea; that, at Ferrara, which is 60 or 70 miles from the mouth of the river, the banks are a⯑bout 20 feet above the ordinary level of the water; but that, at 10 or 12 miles from the ſea, though the channel be equally narrow as at Ferrara, they are not above 12 feet*.
In fine, the theory of running waters is ſub⯑ject to many difficulties. It is not eaſy to give general rules that will apply to every particular caſe. For this purpoſe, experience is preferable to ſpeculation: It is not enough that we know the common effects of rivers in general; but, if we would reaſon juſtly, and give ſtability to our operations, we ought to ſtudy the peculiari⯑ties of particular rivers in which we have an intereſt. Though the remarks I have made be generally new, a greater collection is neceſſary; and perhaps we ſhall in time acquire a diſtinct knowledge of this ſubject, and be enabled to give certain rules for directing and confining rivers in ſuch a manner as will prevent the de⯑ſtruction of bridges, banks, and other damages occaſioned by the impetuoſity of the waters.
The greateſt rivers of Europe are, the Wol⯑ga, the courſe of which, from Reſchow to Aſtra⯑can on the Caſpian Sea, is about 650 leagues; the Danube, which runs about 450 leagues, [267] from the mountains of Switzerland to the Black Sea; the Don, the courſe of which, from the ſource of the Soſna, which receives it, to the Black Sea, is 400 leagues; the Nieper, which likewiſe falls into the Black Sea, after running 350 leagues; the Duine, which empties itſelf in the White Sea, runs a courſe of about 300 leagues, &c.
The greateſt rivers of Aſia are, the Hoanho, which riſes at Raja-Ribron, and, after running 850 leagues, falls into the middle of the gulf of Changi, in the Chineſe ſea; the Jeniſca, which runs from Lake Selinga to the northern ſea of Tartary, a courſe of about 800 leagues; the Oby, the courſe of which, from Lake Kila to the north ſea beyond Waigat's Straits, is about 600 leagues; the river Amour, in eaſt Tartary, has a courſe of 575 leagues, from the head of the river Kerlon, which falls into it, to the ſea of Kamtſchatka; the river Menan may be meaſured from the ſource of the Longmu, which falls into it, to its mouth at Poulo-con⯑dor; the Kian, the courſe of which is about 550 leagues, from the ſource of the Kinxa, which it receives, to its termination in the ſea of China; the Ganges, which has a courſe near⯑ly of the ſame extent with the Kian; the Eu⯑phrates, computing from the ſource of the Ir⯑ma, which it receives, runs about 500 leagues; the Indus, which runs about 400 leagues, and falls into the Arabian ſea on the eaſt of Guza⯑rat; [268] and the Sirderoias, which runs about 400 leagues, and falls into Lake Aral.
The greateſt rivers of Africa are, the Sene⯑gal, the courſe of which, comprehending the Niger, which is a continuation of it, and the ſource of the Gombarou, which falls into the Niger, is about 1125 leagues; the Nile, which riſes in Upper Aethiopia, runs about 970 leagues. There are others, the courſes of which are but partially known, as the Zaira, the Coanza, the Couama, and the Quilmanci, each of which we are acquainted with to the extent of 400 leagues.
Laſtly, in America, the river of the Ama⯑zons runs more than 1200 leagues, if we rec⯑kon from the lake near Guanuco, 30 leagues from Lima, where the Maragnon riſes; or, even computing from the ſource of the river Napo, near Quito, the courſe of the Amazons is more than 1000 leagues*.
The courſe of the river St Lawrence in Cana⯑da is more than 900 leagues, computing from its mouth to Lake Ontario, from that to Lake Huron, Lake Superior, Lake Alemipigo, Lake Chriſtinaux, and the lake of the Aſſiniboils, the waters of all which fall into one another, and at laſt into the river St Lawrence.
The river Miſſiſippi runs more than 700 leagues, from its mouth to any of its ſources, which are not far from the lake of the Aſſini⯑boils.
[269] The river Plata extends more than 800 leagues, from its mouth to the ſource of the Parana, which it receives.
The river Oronoko runs more than 575 leagues, reckoning from the ſource of the river Caketa, near Paſto, which partly falls into the Oronoko, and partly runs towards the river of the Amazons*.
The Madera, which falls into the Amazons, extends more than 660 leagues.
In order to compute the quantity of water diſcharged into the ſea by all the rivers, we ſhall ſuppoſe, which is nearly the truth, that one half of the earth's ſurface is ſea, and the other half dry land: We ſhall likewiſe ſuppoſe the mean depth of the ſea to be about 230 fathoms. The total ſurface of the earth is 170981012 ſquare miles, and that of the ſea is 85490506 ſquare miles, which being multiplied by 1-fourth, the depth of the ſea, gives 21372626 cubic miles for the quantity of water contained in the whole ocean. Now, to compute the quantity diſcharged into the ocean by the rivers, let us take a river, the velocity and quantity of whoſe waters are known; the Po, for example, which paſſes through Lombardy, and waters a country of 380 miles in length. According to Riccioli, the breadth of the Po, be⯑fore it divides into branches, is 100 perches of Boulogne, or 1000 feet; and its depth is 10 feet; and it runs at the rate of 4 miles in an [270] hour: Conſequently, the Po diſcharges into the ſea 200,000 cubical perches of water in an hour, or 4,800,000 in a day. But a cubic mile con⯑tains 125,000,000 cubic perches; of courſe, it will require 26 days to diſcharge into the ſea a cubic mile of water. It only remains to deter⯑mine the proportion that the Po bears to all the rivers of the earth taken together, which cannot be done exactly. But, to approach nearly to the truth, let us ſuppoſe that the quantity of water which the ſea receives from the great rivers in every country, is proportioned to the extent of the ſurfaces of theſe countries; and, conſequent⯑ly, that the country watered by the Po, and by the rivers which fall into it, is to the total ſur⯑face of the dry land as the Po is to all the rivers of the earth. Now, by the moſt exact charts, it appears, that the Po, from its origin to its mouth, traverſes a country of 380 miles in length; and the rivers which fall into it on each ſide ariſe from ſources which are about 60 miles diſtant from the Po. Thus, the Po, and the ri⯑vers it receives, water a country 380 miles long, and 120 broad, which makes 45600 ſquare miles. But the ſurface of the dry land is 85490506 ſquare miles; conſequently, the quan⯑tity of water carried to the ſea by all the rivers will be 1874 times greater than the quantity diſcharged by the Po. But, as 26 rivers, equal to the Po, furniſh a cubic mile of water each day, it follows, that, in the ſpace of a year, [271] 1874 rivers equal to the Po, will carry to the ſea 26308 cubic miles of water; and that, in 812 years, all theſe rivers would diſcharge 21372626 cubic miles, which is a quantity equal to what is contained in the ocean; of courſe, if the ocean were empty, 812 years would be ne⯑ceſſary to fill it by the rivers*.
It is a reſult of this calculation, that the quan⯑tity of water raiſed from the ſea by evapora⯑tion, and tranſported upon land by the winds, is from 20 to 21 inches in the year, or about ⅔ of a French line each day. This evaporation, though tripled to make allowance for what falls back into the ſea from the clouds, is very incon⯑ſiderable. Mr Halley† has clearly demonſtrated, that the vapours tranſported from the ſea, and diſcharged upon the land, are ſufficient to main⯑tain all the rivers and lakes in the world.
After the Nile, the Jordan is the largeſt river in the Levant, or even in Barbary. It diſcharges each day into the Dead Sea about 6,000,000 of tons. All this water, and more, is carried off by evaporation; for, according to Halley's cal⯑culation of 6914 tons evaporated from each ſu⯑perficial mile, the Dead Sea, which is 72 miles long and 18 broad, muſt loſe, every day, by evaporation, near 9,000,000 of tons; that is, not only all the water it receives from the Jor⯑dan, but from the ſmaller rivers which come [272] from the mountains of Moab, and elſewhere. Of courſe, this ſea has no occaſion to communi⯑cate with any other by ſubterraneous paſſages*.
The moſt rapid of all rivers are, the Tigris, the Indus, the Danube, the Yrtis in Siberia, the Malmiſtra in Cilicia, &c.† But, as was for⯑merly remarked, the velocity of rivers depends both on the declivity and the weight of water. In examining the globe, we find, that the Da⯑nube has leſs declivity than the Po, the Rhine, or the Rhone; for, the courſe of the Danube is longer, and it falls into the Black Sea, which is higher than the Mediterranean, and perhaps than the ocean.
Great rivers, in their courſe, are conſtantly receiving ſmall ones into their channels. The Danube, for example, receives more than 200 brooks and rivulets. But, if we reckon only rivers of ſome conſideration, we will find, that the Danube receives 30 or 31, the Wolga 32 or 33, the Don 5 or 6, the Nieper 19 or 20, the Duine 11 or 12. The Hoanho, in Aſia, receives 34 or 35 rivers, the Jeniſca more than 60, the Oby an equal number, the Amour about 40, the Kian, or river of Nankin, 30, the Ganges more than 20, the Euphrates 10 or 11, &c. In Afri⯑ca, the Senegal receives more than 20 rivers; the Nile receives none lower than 500 leagues from its mouth, the laſt which falls into it be⯑ing the Moraba; and from this place to its [273] ſource, it receives about 12 or 13. In America, the Amazones receives more than 60 conſide⯑rable rivers, St Laurence about 40, reckoning thoſe which fall into the lakes, the Miſſiſippi more than 40, the Plata above 50, &c.
Upon the ſurface of the earth, there are ele⯑vated countries which ſeem to be points of par⯑tition marked out by nature for the diſtribution of the waters. In Europe, one of theſe points is Mont Saint-Godard, and its environs. A⯑nother point is the country ſituated between the provinces of Belozera and Wologda in Muſcovy, from which many rivers deſcend, ſome into the White Sea, ſome into the Black, and others into the Caſpian. In Aſia there are ſeveral points of partition, as the country of the Mogul Tartars, ſome of whoſe rivers run into the ſea of Nova Zembla, others into the gulf of Linchidolin, others into the ſea of Corea, and others into that of China; and the Leſſer Thibet, the rivers of which run into the Chineſe ſea, into the gulf of Bengal, the gulf of Cambaia, and the lake Aral. The province of Quito, in America, diſcharges its rivers into the ſouth and north ſeas, and into the gulf of Mexico.
There are, in the Old Continent, about 430 rivers which directly fall either into the Ocean, or into the Mediterranean and Black Seas. But, in the New Continent, we know of only 145 rivers that fall immediately into the ſea. In this [274] number I have reckoned none that are not as large as the river Somme in Picardy.
All theſe rivers tranſport, from the countries through which they paſs, into the ſea, great quantities of mineral and ſaline particles. The particles of ſalt, which diſſolve in water, are eaſily carried down to the ſea. Several philoſophers, and particularly Halley, have alledged, that the ſalt⯑neſs of the ſea proceeds alone from the particles of ſalt tranſported by the rivers: Others main⯑tain, that this ſaltneſs was coeval with the ſea itſelf, and that the ſalt was created to prevent the waters from corrupting. But the agitation of the ſea by the winds and the tides is, I ima⯑gine, a cauſe equally powerful as the ſalt in pre⯑ſerving it againſt putrifaction; for, when bar⯑relled up, it corrupts in a few days. And Boyle informs us of a navigator who was overtaken with a calm which laſted 13 days, and who aſ⯑ſured him, that the water became ſo putrid, that, if the calm had continued much longer, the whole crew would have periſhed*. Sea-water is alſo impregnated with a bituminous oil, which renders it both unwholeſome, and diſagreeable to the taſte. The quantity of ſalt in ſea-water is about a fortieth part, and it is nearly of an equal ſaltneſs at the ſurface and at the bottom, under the Line and at the Cape of Good Hope; though there are ſome particular places, as off the Moſambique coaſt, where it is more ſalt than [275] in others*. It is likewiſe ſaid to be leſs ſalt within the Arctic circle: But this phaenomenon may proceed from the immenſe quantities of ſnow, and the large rivers which fall into theſe ſeas, and from the proportional defect of evapo⯑ration.
However this matter ſtands, I believe, that the ſaltneſs of the ocean is not only occaſioned by the many banks of ſalt at the bottom of the ſea, and along the coaſts, but likewiſe by the ſalts continually brought down by the rivers; that Halley was right in his conjecture that there was originally little or no ſalt in the ſea, but that its ſaltneſs gradually augmented in pro⯑portion as it was ſupplied by the rivers; that the degree of ſaltneſs is perpetually increaſing; and, conſequently, that, by computing the total quantity of ſalt carried down by the rivers, we might be enabled to diſcover the real age of the world. Mr Boyle affirms, on the authority of divers and pearl-fiſhers, that the water is colder in proportion to its depth; and that, at great depths, the cold becomes ſo exceſſive as to oblige them to come up much ſooner than uſual. But the weight of the water may be as much the cauſe of their uneaſineſs as the intenſeneſs of the cold, eſpecially when they deſcend 300 or 400 fathom. Divers, however, ſeldom go deeper than 100 feet. The ſame author relates, that, in a voyage to the Eaſt Indies, when they ar⯑rived [276] at the 35th degree of ſouth latitude, they ſounded to the depth of 400 fathoms, and when the lead, which weighed about 30 pounds, was drawn up, it had become as cold as ice. It is likewiſe a common practice at ſea, to ſink the bottles ſeveral fathoms, in order to cool their wine; and, it is ſaid, that the deeper the bottles are ſunk, the wine becomes the cooler.
Theſe facts would lead us to imagine, that the ſea-water was ſalter at the bottom than at the ſurface. But they are oppoſed by facts of a contrary nature: Experiments have been made with veſſels which opened only at a certain depth, and the water was not found to be ſalter than that at the ſurface. There are even examples of the water at the bottom being freſher than at the ſurface: This phaenomenon is exhibited in all thoſe places where ſprings ariſe from the bot⯑tom of the ſea, as near Goa, at Ormus, and in the ſea of Naples, in which there are many warm ſprings.
In other places, ſulphurous ſprings and beds of bitumen have been diſcovered at the bottom of the ſea; and, upon land, there are numerous ſprings of bitumen that run down into the ſea. At Barbadoes, there is a fountain of bitumen which runs from the rocks into the ſea. Bitumen and ſalt, then, are the principal ingredients in ſea⯑water. But it is blended with many other ſub⯑ſtances; for its taſte differs conſiderably in dif⯑ferent parts of the ocean: Beſides, agitation and [277] the heat of the ſun change the natural taſte of ſea-water, and the different colours of different ſeas, and even of the ſame ſea at different times, prove it to be mixed with many heterogeneous bodies, which are detached either from the bot⯑tom, or carried down by the rivers.
Moſt countries that are furniſhed with large rivers are ſubject to periodical inundations; and thoſe rivers which have long courſes overflow with the greateſt regularity. Every body has heard of the inundations of the Nile, the waters of which, though ſpread over a large track of country, and at a great diſtance from the ſea, preſerve their ſweetneſs and tranſparency. Strabo and other antient authors tell us, that the Nile had ſeven mouths; but now only two that are navigable remain: A third canal, indeed, ſup⯑plies the ciſterns of Alexandria; and there is a fourth which is ſtill leſs conſiderable. As the cleaning of their canals has long been neglected, they are moſtly in ruins. In theſe works the antients annually employed a vaſt number of workmen and ſoldiers, who carried off the mud and ſand which this river brings down in great quantities. The overflowing of the Nile is oc⯑caſioned by the rains that fall in Aethiopia: They begin in April, and end not till September. Du⯑ring the firſt three months, the days are ſerene and beautiful; but the ſun no ſooner ſets, than the rains begin, continue inceſſantly till ſun⯑riſing, and are commonly accompanied with [278] thunder and lightning. The inundation in Egypt begins about the 17th of June; it gene⯑rally takes 40 days in ſwelling, and as many in ſubſiding. The whole flat country of Egypt is overflowed: But the inundation is not now ſo great as in antient times; for Herodotus affirms, that the Nile ſwelled 100 days, and required an equal time to ſubſide. If this fact be true, the difference can be aſcribed to no other cauſe but the gradual elevation of the land by the mud depoſited by the waters, and the diminution in the height of the mountains from which this river derives its ſource. It is natural to think, that the height of the mountains is diminiſhed; for the heavy rains that fall in theſe regions du⯑ring one half of the year, bring down great quantities of ſand and earth from the tops of the mountains into the vallies, from which they are tranſported by torrents into the channel of the Nile, and are partly depoſited on the land by means of the inundations.
The Nile is not the only river that has regu⯑lar and annual overflowings: The Pegu, which is equally regular in its inundations, has, from this circumſtance, got the name of the Indian Nile. It overflows the country for 30 leagues beyond its banks, and, like the Nile, leaves great quantities of mud and ſlime, which enrich the ground ſo much, that it produces excellent pa⯑ſture for cattle, and enables the inhabitants to [279] export rice*. The Niger, or, which is the ſame thing, the upper part of the Senegal, overflows and covers the whole flat country of Nigritia. Its inundation, like that of the Nile, begins about the middle of June, and increaſes for 40 days. The Plata, in Braſil, overflows annually, and at the ſame time with the Nile. The Ganges, the Indus, the Euphrates, and ſome other rivers, produce annual inundations. But all rivers are not ſubject to periodic inundations: Theſe pro⯑ceed from a combination of cauſes, which, at the ſame time, augment the quantity of water, and diminiſh its velocity.
We formerly remarked, that the declivity of rivers gradually diminiſh till they arrive at the ſea. But, in ſome places, the declivity is more ſudden, and forms what is called a cataract, which is nothing more than an unuſually rapid fall of the water. In the Rhine, for example, there are two cataracts, one at Bilefeld, and the other near Schafhouſe. The Nile has ſeveral cataracts, two of the moſt remarkable fall from a great height, between two mountains. In the Wologda, in Muſcovy, there are alſo two, near Ladoga. The Zaire, a river in Congo, com⯑mences with a large cataract which falls from the top of a mountain. But the moſt celebra⯑ted cataract is that of the river Niagara in Ca⯑nada: It falls, in a prodigious torrent, 156 feet of perpendicular height, and is a fourth part of [280] a league in breadth. The vapour of the water riſes to the clouds, is ſeen at the diſtance of five leagues, and, when the ſun ſhines above it, ex⯑hibits a beautiful rainbow. Below this cataract the whirlpools and commotions of the waters are ſo tremendous, as to render navigation im⯑practicable for ſix miles; and above it, the ri⯑ver is much narrower than higher up*. Char⯑levoix† deſcribes it in the following manner:
'My firſt care, after my arrival, was to viſit the nobleſt caſcade, perhaps, in the world; but I preſently found the Baron de la Hontan had committed ſuch a miſtake with reſpect to its height and figure, as to give grounds to believe he had never ſeen it. It is certain, that, if you meaſure its height by that of the three moun⯑tains you are obliged to climb to get at it, it does not come much ſhort of what the map of M. Deſliſle makes it, that is, 600 feet, having certainly gone into this paradox, either on the faith of the Baron de la Hontan, or Father Hennepin. But after I arrived at the ſummit of the third mountain, I obſerved, that, in the ſpace of three leagues, which I had to walk before I came to this piece of water, though you are ſometimes obliged to aſcend, you muſt yet deſcend ſtill more, a circumſtance to which travellers ſeem not to have ſufficiently attend⯑ed. As it is impoſſible to approach it but on [281] one ſide only, and conſequently to ſee it, ex⯑cepting in profile, or ſideways; it is no eaſy matter to meaſure its height with inſtruments. It, has, however, been attempted by means of a pole tied to a long line, and, after many re⯑peated trials, it has been found only 115, or 120 feet high. But it is impoſſible to be ſure that the pole has not been ſtopt by ſome pro⯑jecting rock; for, though it was always drawn up wet, as well as the end of the line to which it was tied, this proves nothing at all, as the water which precipitates itſelf from the moun⯑tain, riſes very high in foam. For my own part, after having examined it on all ſides, where it could be viewed to the greateſt ad⯑vantage, I am inclined to think we cannot al⯑low it leſs than a hundred and forty, or fifty feet.'
'As to its figure, it is in the ſhape of a horſe⯑ſhoe, and is about 400 paces in circumference; it is divided into two, exactly in the middle, by a very narrow iſland, half a quarter of a league long. It is true, thoſe two parts very ſoon unite; that on my ſide, and which I could only have a ſide view of, has ſeveral branches which project from the body of the caſcade, but that which I viewed in front, appeared to me quite entire. The Baron de la Hontan mentions a torrent, which, if this author has not invented it, muſt certainly fall through ſome channel on the melting of the ſnows.'
[282] Three leagues from Albany, in the province of New York, there is a cataract of 50 feet per⯑pendicular height, the vapour of which gives riſe alſo to a rainbow*.
In every country where the number of men is too inconſiderable for forming and ſupporting poliſhed ſocieties, the ſurface of the earth is more unequal and rugged, and the channels of rivers are more extended, irregular, and often in⯑terrupted by cataracts. The Rhone and the Loire would require the operation of ſeveral ages before they became navigable. It is by conſining and directing the waters, and clearing the bottoms of rivers, that they acquire a fixed and determinate courſe. In thinly inhabited regions, nature is always rude, and ſometimes deformed.
Some rivers loſe themſelves in the ſands, and others ſeem to precipitate into the bowels of the earth. The Guadalquiver in Spain, the river of Gottenburg in Sweden, and even the Rhine, diſappear under ground. It is affirmed, that, in the weſt part of the iſland of St Domingo, there is a pretty high mountain, at the foot of which are ſeveral large caverns, that receive the rivers and brooks; and the noiſe of their fall is heard at the diſtance of ſeven or eight leagues†. The number of rivers, however, that diſappear in the earth, is very ſmall; and they ſeem not to de⯑ſcend [283] very deep. It is more probable, that, like the Rhine, they loſe themſelves by dividing and diſperſing through a large ſurface of ſand, which is very common with thoſe ſmall rivers that run through dry and ſandy ground, of which there are many examples in Africa, Perſia, Arabia, &c.
The rivers of the north carry down to the ſea prodigious quantities of ice, which, by accu⯑mulating, form thoſe enormous maſſes, ſo dan⯑gerous to the mariner. The ſtraits of Waigat, which is frozen during the greateſt part of the year, is moſt remarkable for theſe maſſes of ice, which are conſtantly brought into the ſtraits by the river Oby. They attach themſelves all a⯑long the coaſts, and riſe to great heights. The middle of the ſtrait freezes laſt, and the ice, of courſe, does not riſe ſo high as on each ſide. When the north wind ceaſes, and it blows in the direction of the ſtraits, the ice begins to melt and to break in the middle; then large maſſes are detached, and tranſported into the open ſea. The wind, which blows during the whole win⯑ter from the north, over the frozen country of Nova Zembla, renders the regions watered by the Oby, and all Siberia, ſo cold, that, at Tobol⯑ſki, in the 57th degree, there are no fruit trees, though at Stockholm in Sweden, and even in higher latitudes, they have fruit trees and legu⯑minous plants. This difference proceeds not, as has been imagined, from the ſea of Lapland [284] being colder than that of the ſtraits, nor from the country of Nova Zembla being colder than that of Lapland, but from this circumſtance alone, that the Baltic and the ſea of Bothnia ſoften the rigour of the north wind; whereas, in Siberia, there is nothing to check its activity. This ſo⯑lution is a reſult of experience. The cold is never ſo intenſe near the ſea coaſts as in the in⯑terior parts of a country. There are plants which endure the open air all winter at London, which cannot be preſerved at Paris: And Sibe⯑ria, which is a vaſt continent, is, for this reaſon, colder than Sweden, which is almoſt ſurround⯑ed with the ſea.
Spitzbergen is the coldeſt country in the world: It runs as far as the 78th degree of north latitude, and is compoſed of ſmall, pointed mountains. Theſe mountains conſiſt of gravel, and of flat ſtones, like gray ſlate, heaped upon one another. According to the accounts of voy⯑agers, theſe hills are raiſed by the winds, and new ones appear every ſeaſon. In this country no quadrupeds live but the rein-deer, which feeds upon moſs. Beyond theſe hills, and a⯑bove a league from the ſea, the maſt of a ſhip was lately found with a pully fixed to one end of it; from which circumſtance, it has been concluded, that this is a new country, and that it was formerly covered with the ſea: It is un⯑inhabited and uninhabitable; for the hills have no conſiſtence, but are looſe and moveable; and [285] a vapour proceeds from the earth, ſo cold and penetrating, as to preclude the poſſibility of re⯑maining any time upon this dreary and inhoſ⯑pitable land.
The whale-fiſhing veſſels arrive at Spitzber⯑gen in July, and depart from it about the mid⯑dle of Auguſt, the ice not permitting them to arrive ſooner, or to remain longer. In theſe ſeas there are prodigious boards of ice, clear and ſhining as glaſs, and from 60 to 80 fathom thick; and, in ſome places, the ſea appears to be frozen to the bottom*.
The ſeas of North America are likewiſe much infeſted with ice, as in Aſcenſion-bay, in Hud⯑ſon's, Cumberland's, Davis's, and Frobiſher's ſtraits, &c. We are aſſured by Robert Lade, that the mountains of Frieſland are entirely co⯑vered with ſnow; and that the ice ſurrounds the coaſts, and, like a bulwark, prevents all approach to them. 'It is remarkable,' ſays he, 'that, in this ſea, we meet with iſlands of ice, more than half a league in circumference, exceedingly high, and that deſcend from 70 to 80 fathoms deep. This ice, which is ſweet, is perhaps o⯑riginally formed in the rivers or ſtraits of the adjacent lands, &c. Theſe iſlands or moun⯑tains of ice are moveable, and , in ſtorms, they follow the tract of a ſhip, as if they were drawn after her by a rope. Some of them [286] riſe ſo high above water, that they ſurmount the tops of the talleſt maſts*,' &c.
In the voyages collected for the uſe of the Dutch Eaſt India Company, we have the fol⯑lowing account of the ice off Nova Zembla: 'At Cape Trooſt, the weather was ſo foggy, as to oblige us to moor our veſſel to a bank of ice, which was 36 fathoms below, and 16 a⯑bove the ſurface of the water. On the 10th of Auguſt, the ice began to ſeparate, and to float; we then remarked, that the maſs to which our veſſel had been moored, touched the bottom; for, though the others were all in motion, and ſtruck againſt it, and againſt each other, it remained immoveable. We were now afraid of being frozen in, or daſhed to pieces by the ice; we, therefore, endeavour⯑ed to eſcape from this latitude, though the veſ⯑ſel, in her courſe, was obliged to puſh through the ice, which made a great noiſe round us for a conſiderable diſtance: We at laſt anchored along another board of ice, where we remain⯑ed that night.'
'During the firſt watch, the ice began to ſplit, with an inconceivable noiſe. The ſhip's head kept ſo ſtrongly to the current in which the ice-boards floated, that we were obliged to veer the cable in order to get her off. We counted above 400 blocks of ice, which ſank [287] 10 fathoms below the water, and appeared to riſe about 2 fathoms above it.'
'We then moored the veſſel to another block of ice, which was immerſed below the ſurface about ſix fathoms. At a little diſtance from this ſtation we perceived a large bank, which was pointed like a cone, and reached to the bottom of the ſea: We approached it, and found it to be 20 fathoms below, and about 12 above the ſurface of the water.'
'On the 11th, we ſailed up to another bank, which was 18 fathoms below the ſurface, and 10 fathoms above it.'
'The Dutch, on the 21ſt, advanced a great way between the boards of ice, and anchored during the night. Next morning they retired, and moored to a bank which was 18 fathoms below, and 10 above the water. They climbed to the top, and remarked, as a ſingular phaeno⯑menon, that it was covered with earth, and that they found there about 40 eggs. Its colour was a fine azure blue, and totally diffe⯑rent from that of the other maſſes. This cir⯑cumſtance gave riſe to various ſpeculations; ſome imagining it to be an effect of the ice, and others thought the whole was a maſs of frozen earth*.'
Wafer met with many floating pieces of ice off Terra del Fuego, which were ſo large that [288] he at firſt imagined them to be iſlands: Some of them, he remarks, appeared to be a league or two in length, and the largeſt of them ſeemed to riſe 400 or 500 feet above the ſurface of the water.
All theſe boards of ice, as I have remarked in the 6th Article, are tranſported from the rivers into the ſea. Thoſe in the ſea of Nova Zembla and in the Straits of Waigat, come from the Oby, and, perhaps, from the Jeniſca, and other great rivers in Siberia and Tartary; thoſe of the Hudſon's Straits, from Aſcen⯑ſion-bay, into which many rivers in North A⯑merica empty themſelves; and thoſe of Terra del Fuego, from the ſouthern continent. If fewer of them appear in the northern coaſts of Lapland than in thoſe of Siberia and Waigat's Straits, it is becauſe all the Lapland rivers fall into the gulf of Bothnia, and none of them in⯑to the north ſea. They may likewiſe be formed in ſtraits, where the tides riſe higher than in the open ſea; and, conſequently, where the boards of ice that float on the ſurface may accumulate and produce maſſes or banks of ſeveral fathoms high. But, with regard to thoſe which riſe to the height of four or five hundred feet, it ap⯑pears, that they can no where be produced but near very elevated coaſts; and I imagine, that, when the ſnows which cover theſe coaſts melt, the water runs down upon the boards of ice, and, by freezing anew, gradually augment their [289] ſize, till they arrive at this amazing height; that, in a warm ſummer, the action of the winds, the agitation of the ſea, and perhaps their own weight, may detach them from the coaſts, and ſet them adrift; and that they may even be tranſported into temperate climates before they are entirely diſſolved.
THE dry land is every where ſurrounded by the ocean: It penetrates, ſometimes by large openings, and ſometimes by ſmall ſtraits, into the interior parts of different countries; and it forms mediterranean ſeas, ſome of which are affected by the motion of the tides, and others not. We ſhall, in this article, trace the ocean through all its windings; and, at the ſame time, give an enumeration of all the mediterranean ſeas, which we ſhall endeavour to diſtinguiſh from what are called bays or gulfs, and lakes.
The ſea that waſhes the weſtern coaſts of France, forms a gulf between Spain and Bri⯑tain. This gulf is, by navigators, called the Bay [291] of Biſcay: It is very open, and advances far⯑theſt into the land between Bayonne and St Se⯑baſtian. It likewiſe advances conſiderably at Rochelle and Rochefort. This bay begins at Cape Ortegal, and terminates at Breſt, where a ſtrait commences between the ſouth point of Britain and Cape Lizard. This ſtrait, which is at firſt pretty wide, forms a ſmall bay on the coaſt of Normandy, the moſt advanced point of which is at Auranche. It continues pretty large till it arrives at the channel of Calais, where it is very narrow; it then ſuddenly enlarges, and terminates between the Texel and the coaſt of Norwich: At the Texel, it forms a ſmall ſhallow mediterranean called Zuiderſee, and ſeveral large gaps or advances, whoſe waters are not of a con⯑ſiderable depth.
After this, the ocean forms a large bay called the German Sea, which commences at the north⯑moſt point of Scotland, and runs along the eaſt coaſt of Britain the length of Norwich; and from thence to the Texel, along the coaſts of Holland and Germany, of Jutland and Norway, as far as Bergen. This bay may even be con⯑ſidered as a mediterranean; for the Orkney iſlands nearly ſhut up its mouth, and ſeem, by their direction, to be a continuation of the moun⯑tains of Norway. It forms a large ſtrait, which commences at the ſouth point of Norway, and continues pretty broad to the iſland of Zetland, where it ſuddenly contracts, and forms, between [292] the coaſts of Sweden and the iſlands of Denmark and Jutland, four ſmall ſtraits; after which, it widens to a ſmall bay, the moſt advanced point of which is at Lubec; from thence, to the ſouth extremity of Sweden, it continues pretty broad; then it enlarges more and more, and forms the Baltic, which is a mediterranean ſea, extending, from ſouth to north, near 300 leagues, if the gulph of Bothnia, which, in effect, is a continu⯑ation of it, be comprehended. In the Baltic are two bays, that of Livonia, the moſt advanced point of which is near Mittau and Riga, and that of Finland, which is a branch of the Baltic, extending between Livonia and Finland to Pe⯑terſburgh, and communicating with lake Ladoga, and even with lake Onega, which joins the white ſea by means of the river Onega. The whole body of water which forms the Baltic, the Gulfs of Bothnia, of Finland, and of Livonia, ought to be regarded as an immenſe lake, ſupported by a great number of rivers, as the Oder, the Vi⯑ſtula, the Niemen, the Droine in Germany and Poland; by other rivers in Livonia and Finland, by others ſtill more conſiderable that come from Lapland, as the Tornea, the Calis, the Lula, the Pithea, the Uma; and by ſeveral from Sweden. Theſe rivers, which in general are large, amount in all to more than 40, computing thoſe which fall into them, and cannot fail to convey a quan⯑tity of water ſufficient to ſupply the Baltic. Be⯑ſides, there are no tides in the Baltic, and its [293] water has very little faltneſs: And, if the ſitua⯑tion of the land, and the number of lakes and marſhes in Finland and Sweden, which are con⯑tiguous to the Baltic, be taken into conſideration, we ſhall be inclined to regard it not as a ſea, but as a great lake formed by the waters which it receives from the adjacent countries, and which have forced for themſelves a paſſage near Den⯑mark into the ocean, into which, according to the relation of voyagers, it ſtill continues to run.
From the commencement of the bay which goes by the name of the German Sea, and which terminates beyond Bergen, the ocean follows the coaſts of Norway, Swediſh Lapland, North Lapland, and Muſcovite Lapland, at the eaſtern part of which it forms a large ſtrait, and gives riſe to the mediterranean called the White Sea, which may alſo be conſidered as a great lake; for it receives twelve or thirteen large rivers, which are more than ſufficient to ſupply it with water; and its water contains but little ſalt. Beſides, it is within a trifle, in ſeveral places, of communicating with the Baltic; and it has an evident communication with the gulf of Fin⯑land; for, in aſcending the river Onega, we arrive at a lake of the ſame name, which is joined by two rivers to lake Ladoga; and this laſt communicates by a large branch with the gulf of Finland; and there are, in Swediſh Lapland, ſeveral places from which the waters run almoſt indifferently either into the White [294] Sea, or into the gulfs of Bothnia and of Fin⯑land. This whole country being full of lakes and marſhes, it, therefore, ſeems probable, that the Baltic and White Seas were the receptacles of its waters, and that, in time, they diſcharged themſelves into the German and Frozen ſeas.
On leaving the White Sea, and coaſting the iſland of Candenos, and the north of Ruſſia, the ocean advances a ſmall arm into the land at the mouth of the river Petzora. This arm, which is about 40 leagues in length, by 8 or 10 in breadth, may rather be regarded as a collection of water formed by the river, than as a gulf of the ſea; and it alſo contains very little ſalt. In this place the land runs out in a promontory terminated by the ſmall iſlands of Maurice and of Orange, and between this promontory and the neighbouring land to the ſouth of Waigat's ſtraits, there is a bay of about 30 leagues long, which belongs to the ocean, and is not formed by rivers. This is ſucceeded by Waigat's ſtraits, which lies nearly under the 70th degree of north latitude; it is not above 8 or 10 leagues in length, and it communicates with the ſea which waſhes the north coaſts of Siberia. As this ſtrait is blocked up with ice during the greateſt part of the year, it is very difficult to penetrate into the ſea beyond it. This paſſage has been tried in vain by many navigators; and thoſe who ſucceeded have not given us exact charts of this ſea, which they call the Pacific [295] Sea. By the moſt recent charts, and by the beſt globes, it appears, that this ſea may be only a mediterranean, having no connection with the great ſea of Tartary; for it ſeems to be ſhut up and bounded to the ſouth by the country of the Samoides, which is now well known, and which extends from the Straits of Waigat to the mouth of the river Jeniſca: To the eaſt, it is bounded by Jelmorland; to the weſt by Nova Zembla; and, though we know not the extent of this ſea to the north and north-eaſt, as the land ſeems not to be interrupted, it is probable that the Pa⯑cific Sea is only a mediterranean; and that it is bounded by land, and has no communication on that ſide with the ocean. What eſtabliſhes this fact is, that, in departing from the Straits of Waigat, the whole weſt and north coaſts of No⯑va Zembla, the length of Cape Deſire, have been traverſed; that, from this Cape, the coaſts of Nova Zembla have been traced to a ſmall bay about the 75th degree, where ſome Dutchmen paſſed a dreadful winter in 1596; and that, be⯑yond this gulf, the land of Jelmorland was diſcovered in 1664, which is ſeparated from Nova Zembla only by a few leagues of land; ſo that the only land unknown is a ſmall ſpot near this little bay juſt now deſcribed; and this ſpot ex⯑ceeds not, perhaps, 30 leagues in length. If, therefore, the Pacific Sea joins with the eaſtern ocean, it muſt be by means of this ſmall bay, which is the only way by which this mediter⯑ranean [296] can have any communication with it. And, even on the ſuppoſition that ſuch a com⯑munication exiſted, as this bay lies in the 75th degree of latitude, it would be neceſſary, to gain this open ſea, to keep five degrees farther north. It is apparent, therefore, that, in attempting a north paſſage to China, it is better to ſail beyond Nova Zembla to the 77th or 78th degree, where the ſea is more open and clearer of ice, than to perſiſt in paſſing the frozen ſtraits of Waigat, when it is even uncertain whether the ſea be⯑yond them has any communication with the eaſtern ocean.
The coaſt has been traced from Nova Zem⯑bla and Jelmorland to the mouth of the Chotan⯑ga, which is about the 73d degree; beyond which an unknow coaſt extends about 200 leagues. We only know, from the Ruſſians who travelled by land into theſe climates, that the country is not interrupted; and, in their charts, the rivers are delineated, and they called the inhabitants Populi Palati. This interval of unknown coaſt extends from the mouth of the Chotanga to that of Kauvoina, in the 66th de⯑gree of latitude. The bay of Linchidolin, in which the Ruſſians fiſh whales, advances far⯑theſt into the land at the mouth of the Len, which is a conſiderable river. This bay is very open, and pertains to the ſea of Tartary.
From the mouth of the Len, the northern coaſt of Tartary runs about 500 leagues eaſt⯑ward [297] to a peninſula inhabited by a people called Schelates; it is the moſt northern point of Tar⯑tary, and lies under the 72d degree of latitude. In this 500 leagues, the ocean forms neither bays nor arms; only, from the peninſula of the Schelates, to the mouth of the Korvinea, the coaſt has a conſiderable winding. This point is the eaſtern extremity of the north coaſt of the Old Continent, and Cape North in Lapland is the weſtern extremity. Thus, we have of northern coaſt, from Cape North in Lapland, to the extre⯑mity of the country of the Schelates, an extent of 1700 leagues, including the ſinuoſities of bays; and it meaſures about 1100 leagues in a ſtraight line.
Let us next take a ſurvey of the eaſtern coaſts of the Antient Continent, commencing at the extreme point of the country of the Schelates, and deſcending towards the equator. The ocean firſt makes a turn between the country of the Schelates and that of the Tſchutſchi, which laſt projects conſiderably into the ſea. To the ſouth of this country, there is a ſmall open bay, called the bay of Suctoikret; this bay is ſucceeded by another, which advances, like an arm, about 40 or 50 leagues into the land of Kamtſchatka: After which the ocean flows in, by a narrow ſtrait, full of ſmall iſlands, between the ſouthern point of Kamtſchatka and the northern point of the land of Jeſſo, and forms a large medi⯑terranean, which we ſhall now deſcribe in de⯑tail. [298] It conſiſts of the ſea of Kamtſchatka, in which there is a conſiderable iſland, called the iſland of Amour. An arm of this ſea runs north-eaſt. But, both this arm and the ſea of Kamtſchatka may, at leaſt in part, be formed by the waters from the rivers which flow into it from the lands of Kamtſchatka, and thoſe of Tartary. However this matter ſtands, the ſea of Kamtſchatka communications, by a very long ſtrait, with the ſea of Corea, which is ano⯑ther part of this mediterranean; and the whole together, extending more than 600 leagues in length, is bounded, on the weſt and north, by the lands of Corea and Tartary; and, on the eaſt and ſouth, by thoſe of Kamtſchatka, Jeſſo, and Japan, without having any other communi⯑cation with the ocean than by the ſtrait between Kamtſchatka and Jeſſo; for, it is uncertain whether the communication between Japan and the land of Jeſſo, though laid down in ſome charts, has a real exiſtence; and, even ſuppoſing it did exiſt, the ſea of Kamtſchatka and that of Corea would ſtill be regarded as forming toge⯑ther a great mediterranean, ſeparated on all ſides from the ocean, and not as a bay; for it communicates not with the ocean by its ſouth⯑ern ſtrait, but with the Chineſe Sea, which is rather a mediterranean than a bay.
In the preeceding article, it was remarked, that the ſea had a conſtant motion from eaſt to weſt; and that, conſequently, the great Pacific Ocean [299] is making continual efforts againſt the eaſtern coaſts. An accurate examination of the globe will confirm the concluſions we have drawn from this obſervation; for, it appears, that, from Kamtſchatka to New Britain, diſcovered by Dampier in 1700, and which lies in the 4th or 5th degree of ſouth latitude, the ocean has encroached on theſe coaſts to the extent of 400 leagues; and, of courſe, that the eaſtern bounds of the Old Continent ſtretch not ſo far as they did formerly; for, it is remarkable, that New Britain and Kamtſchatka, which are the moſt advanced lands to the eaſt, lie under the ſame meridian. Beſides, all countries extend fartheſt from north to ſouth. Kamtſchatka makes a point of about 160 leagues from north to ſouth, and this point, the eaſtern coaſt of which is waſhed by the Pacific Ocean, and the other by the mediterranean above deſcribed, is divided from north to ſouth by a chain of mountains. The lands of Japan and of Jeſſo form another territory between the ocean and the ſea of Co⯑rea, extending from north to ſouth more than 400 leagues; and the direction of the chains of mountains in Jeſſo and Japan muſt be from north to ſouth; becauſe, in this direction, they extend 400 leagues; but, from weſt to eaſt, they exceed not 50 or 60. Thus, Kamtſchatka, Jeſſo, and the eaſtern part of Japan, ought to be conſidered as contiguous lands, lying in a direction from north to ſouth: And, following [300] the ſame direction, we find, after the point of Cape Ava in Japan, the iſland of Barnevelt, and three other iſlands, ſituated in a line from north to ſouth, and extending about 100 leagues. We next meet with three iſlands, called Calla⯑nos, and after theſe, the Ladrone iſlands, to the number of 14 or 15, all ſtretching in a line from north to ſouth, the whole occupying a ſpace of 300 leagues in length; and the broad⯑eſt part of theſe iſlands, from eaſt to weſt, ex⯑ceeds not 8 leagues. From theſe facts, I am led to conclude, that Kamtſchatka, Jeſſo, the eaſt part of Japan, the iſlands of Barnevelt, the Callanos, and the Ladrones, are a continuation of the ſame chain of mountains, and the remains of an antient country, which has been gradu⯑ally corroded and covered with the ſea. All theſe countries appear to be nothing but moun⯑tains, of which the iſlands are the peaks or points, the low-lands being occupied by the ocean. What, therefore, is related in the Lettres Edeſiantes is true; and, in fact, a number of iſlands, called the New Philippines, has been diſcovered in the very ſituation that P. Gobien ſuppoſed them to lie: And, it cannot be doubt⯑ed, that the moſt eaſterly of theſe New Philip⯑pines are a continuation of the chain of moun⯑tains which compoſe the Ladrones; for theſe eaſtern iſlands, to the number of eleven, lie in a line from north to the ſouth, extending in [301] length more than 200 leagues, and, in breadth, the largeſt of them exceeds not eight leagues.
But theſe conjectures may ſeem to be bold, on account of the great diſtances between the iſlands in the neighbourhood of Cape Ava, of Japan, and of the Callanos, between theſe iſlands and the Ladrones, and between the Ladrones and the New Philippines, the firſt interval being about 160 leagues, the ſecond 50 or 60, and the third near 120. But it ought to be conſidered, that chains of mountains often extend much farther below the waters of the ocean; and that theſe intervals are nothing when compared to the extent of land, from ſouth to north, in theſe iſlands or mountains, which, beginning at the interior part of Kamtſchatka, is more than 1100 leagues. But, though this idea concerning the quantity of land gained by the ocean on the eaſtern parts of the Old Continent, and the con⯑tinuation of the mountains, ſhould be rejected, ſtill it muſt be acknowledged, that Kamtſchatka, Jeſſo, Japan, the iſlands of Rois, Formoſa, Vaif, Baſha, Babuyane, Lucca, Mindano, Gilolo, &c. and, laſtly, New Guinea, which extends to New Britain, and is ſituated under the ſame meridian as Kamtſchatka, form a ſtretch of country of more than 2200 leagues, with ſmall interrup⯑tions, the greateſt of which exceeds not, per⯑haps, 20 leagues; ſo that the ocean has ſcooped out an immenſe bay from the interior parts of the eaſtern continent, which begins at Kamt⯑ſchatka, [302] and terminates at New Britain. This bay is interſperſed with numerous iſlands, and has all the appearances of being gained from the land. It is, therefore, probable, that the ocean, by its conſtant motion from eaſt to weſt, has gradually gained this great tract of country from the continent, and has formed ſeveral me⯑diterraneans, as thoſe of Kamtſchatka, of Corea, of China, and perhaps the whole Indian Archi⯑pelago; for the land and the water are ſo blen⯑ded together in this region, that it evidently ap⯑pears to have been a large country deſtroyed by inundations, of which only the eminences and mountainous parts are now to be ſeen, the low⯑er grounds being entirely concealed under the waters of the ocean. This hypotheſis is farther confirmed by the ſhallowneſs of the ſea, and the figures of the innumerable iſlands, which ſeem to be nothing but the tops of moun⯑tains.
If we take a more particular ſurvey of theſe ſeas, we will find, that the northern part of the Chineſe ſea forms itſelf into a great bay, which begins at the iſland of Fungma, and terminates at the frontiers of the province of Pekin, about 50 leagues from this capital of the Chineſe em⯑pire. The moſt advanced and narroweſt part of this bay is called the gulf of Changi. It is pro⯑bable that this gulf, and part of the ſea of China, are encroachments of the ocean, and that the iſlands above deſcribed are the moſt elevated [303] parts of the antient country. Farther ſouth are the bays of Tonquin and of Siam, in the neigh⯑bourhood of which is the peninſula of Malacca, conſiſting of a long chain of mountains that run from north to ſouth; and the Andaman iſlands, which form another chain of mountains, in the ſame direction, ſeem to be only a continuation of the mountains of Sumatra.
After this the ocean forms the great bay of Bengal; where it may be remarked, that the land of the peninſula of Indus makes a concave curve, towards the eaſt, nearly reſembling the great bay of the eaſtern continent, which ſeems to have been produced by the ſame cauſe, name⯑ly, the motion of the ſea from eaſt to weſt. In this peninſula are the mountains of Gates, which extend from north to ſouth; and the iſland of Ceylon appears to have been ſeparated from this part of the continent.
The Maldiva iſlands are nothing but another chain of mountains ſtretching from north to ſouth. Then follows the Arabian gulph, which ſends off four branches or arms; the two largeſt are on the weſt coaſt, and the two ſmalleſt on the eaſt. The firſt arm on the eaſt coaſt is the bay of Cambaia, which extends not above 50 or 60 leagues; but it receives two conſiderable rivers, the Tapta and the Baroche or Mehi. The ſe⯑cond arm or bay on the ſame coaſt is remark⯑able for the rapidity and height of its tides, which alternately advance and retreat more than [304] 50 leagues. Into this bay fall ſeveral rivers, as the Indus, the Padar, &c. which have brought down ſand and mud in ſuch quantities as to ele⯑vate the bottom of the bay, and reduce it nearly to a perfect level. It is owing to this circum⯑ſtance that the tides extend to ſo great a diſtance. The firſt arm on the weſt coaſt is the Perſic gulf, which advances into the land above 250 leagues; and the ſecond is the Red Sea, which, reckoning from the iſland of Socotora, extends above 680 leagues. From the ſtraits of Ormuz and of Babelmandel, theſe two arms ſhould be conſidered as mediterranean ſeas: They are both, indeed affected with the tides; but this is occaſioned by their vicinity to the equator, where the tides [...] higher than in other climates. Beſides, they are both very long and very nar⯑row. The motion of the tides is more rapid in the Red Sea than in the Perſic gulf; becauſe the former is nearly three times as long, and equally narrow, as the latter; neither does it receive any river capable of reſiſting the tide: But the Perſic gulf receives three large rivers at its moſt advanced extremity. It is apparent, that the Red Sea has been formed by an irruption of the ocean; for the ſituation and ſimilarity in the direction of the coaſts on each ſide of the ſtraits of Babelmandel demonſtrate, that this paſſage has been cut by the waters.
At the extremity of the Red Sea lies that fa⯑mous ſtrip of land called the Iſthmus of Suez, [305] which is a barrier to the junction of the Red Sea with the Mediterranean. In the preceding article, I gave the reaſons which render it pro⯑bable that the Red Sea is higher than the Me⯑diterranean, and that, if the Iſthmus were cut, an inundation and increaſe of the latter would be the conſequence. It may here be added, that, though the ſuperior elevation of the Red Sea ſhould not be allowed, yet, that there are no tides in the Mediterranean near the mouths of the Nile, is an unconteſtible fact. It is equally certain, that the tides in the Red Sea riſe ſeveral feet; and this circumſtance alone, on the ſuppo⯑ſition of the removal of the Iſthmus, would oc⯑caſion a great influx of water from the Red Sea into the Mediterranean. Beſides, Varenius, in his geography*, remarks, 'Oceanus Germa⯑nicus, qui eſt Atlantici pars, inter Friſiam et Hollandiam ſe effundens, efficit ſinum, qui, etſi parvus ſit reſpectu celebrium ſinuum ma⯑ris, tamen et ipſe dicitur mare, alluitque Hol⯑landiae emporium celeberrimum, Amſteloda⯑mum. Non procul inde abeſt lacus Harle⯑menſis, qui etiam mare Harlemenſe dicitur. Hujus altitudo non eſt minor altitudine ſinus illius Belgici, quem diximus, et mittit ramum ad urbem Leidam, ubi in varias foſſas divarica⯑tur. Quoniam itaque nec lacus hic, neque ſi⯑nus ille Hollandici maris inundant adjacentes agros, (de naturali conſtitutione loquor, non [306] ubi tempeſtatibus urgentur, propter quas agge⯑res facti ſunt); patet inde, quod non ſint al⯑tiores quam agri Hollandiae. At vero Oceanum Germanicum eſſe altiorem quam terras haſce, experti ſunt Leidenſes, cum ſuſcepiſſent foſſam ſeu alveum ex urbe ſua ad Oceani Germanici littora, prope Cattorum vicum perducere, (di⯑ſtantia eſt duorum milliarium) ut, recepto per alveum hunc mari, poſſent navigationem inſti⯑tuere in Oceanum Germanicum, et hinc in va⯑rias terrae regiones. Verumenimvero, cum magnam jam alvei portam perfeciſſent, deſiſtere coacti ſunt, quoniam tum demum per obſerva⯑tionem cognitum eſt, Oceani Germanici aquam eſſe altiorem quam agrum inter Leidam et lit⯑tus Oceani iſtius: Unde locus ille, ubi fodere deſierunt, dicitur Het malle Gat. Oceanus ita⯑que Germanicus eſt aliquantum altior quam ſinus ille Hollandicus,' &c. As the German ocean, therefore, is higher than the ſea of Hol⯑land, there is nothing to prevent us from be⯑lieving that the Red Sea may be higher than the Mediterranean. Herodotus and Diodorus Si⯑culus mention a canal of communication be⯑tween the Nile, the Mediterranean, and the Red Sea: And M. de l'Iſle, in 1704, publiſhed a map, in which he has laid down the termination of a canal in the eaſt branch of the Nile, which he imagined to be a part of that which former⯑ly joined that river to the Red Sea* We meet [307] with the ſame opinion in a book entitled Con⯑noiſſance de l'Ancien Monde; where the author, copying Diodorus Siculus, farther informs us, that this canal was begun by Neco King of Egypt; that Darius King of Perſia continued the work; that it was finiſhed by Ptolomy II. who conducted it to the city of Arſinoa; and that it could be ſhut and opened at pleaſure. I pretend not to deny theſe facts; but, I confeſs, they appear to be doubtful. I ſuſpect, that the violence and height of the tides, in the Red Sea, would neceſſarily produce and communicate their influence to the waters of the canal: At leaſt, it would require great precaution to pre⯑vent inundations, and to keep the canal in pro⯑per repair. Though we are told by hiſtorians that this canal was begun and finiſhed, they are ſilent as to its duration; and the remains of it, which are pretended ſtill to exiſt, are perhaps all that was ever executed. This branch of the ocean has been denominated the Red Sea, be⯑cauſe, wherever there are madrepores or corals at the bottom, the water of it has the appearance of this colour. The following deſcription of it is given in the Hiſtoire Generale des Voyages *: 'Before leaving the Red Sea, D. Jean inquired into the cauſes which induced the antients to give it this appellation: He recollected, that Pliny had delivered ſeveral opinions concer⯑ning the origin of this name. Some derived it [308] from a King of that country called Erythros, which, in the Greek language, ſignifies Red: Others imagined that the red colour was occa⯑ſioned by the reflection of the ſun from the ſurface of the water; and others affirmed the water itſelf to be red. The Portugueſe, who had made ſeveral voyages in that ſea, alledged, that the whole coaſt of Arabia was remarkably red; and that the duſt and ſand carried into the ſea by the winds tinged the water with the ſame colour.'
'Dom Jean, who examined the nature of the water and of the coaſts, through their whole extent, with the moſt ſcrupulous attention, aſ⯑ſures us, that the waters of this ſea have no peculiarity in their colour, and that the duſt and ſand, not being red themſelves, could not poſſibly communicate this colour to the water. The land on each ſide, he obſerves, is gene⯑rally brown; in ſome places, it is black, and, in others, white: At Suaquem, the coaſts of which the Portugueſe never viſited, there are three mountains ſtriped with red; but they conſiſt of hard rocks, and the neighbouring ground is of the uſual colour.'
'The truth is, that this ſea is all of the ſame uniform colour, of which any man may ſatis⯑fy himſelf by drawing water from different parts. But, it muſt be acknowledged, that, in ſome places, it appears, by accident, to be red, and, in others, green and white. This phae⯑nomenon [309] admits of the following explication. From Suaquem to Koſſir, which is an extent of 136 leagues, the ſea is filled with banks and rocks of coral; they are ſo called from their reſembling coral in form and colour ſo exact⯑ly, that it is difficult to perceive the diſtinction: There are two kinds of them, the one is white, and the other extremely red. In many places, they are covered with a kind of gum, or viſcid ſubſtance, of a green colour, and ſometimes of a deep orange. Now the water of this ſea is ſo tranſparent, that the bottom is viſible at the depth of twenty fathoms, eſpecially from Suaquem to the extremity of the gulf; and hence the water aſſumes, in appearance, the co⯑lour of the bodies which it covers. When, for example, the rocks are overlaid with a green gum, the water abover them appears to be green; when the bottom is ſand alone, the ſuperincumbent water ſeems to be white; and, when the rocks are covered with coral, the water above them appears to be reddiſh. But, as the rocks of this colour are more frequent than the green or white, Dom Jean concludes, that the Arabic Gulf has, from this circum⯑ſtance, obtained the name of the Red Sea. He was the more ſatisfied with this diſcovery, becauſe the method he employed in the inve⯑ſtigation of it left no room for heſitation or doubt. In ſuch places as were not deep e⯑nough to allow his veſſel to ſail, he faſtened [310] pinks oppoſite to the rocks; and the ſailors were enabled to execute his orders, at more than half a league from the rocks, without be⯑ing immerſed above the middle of their bodies. In thoſe places where the water appeared red, the greateſt part of the ſtones and pebbles they brought up were of the ſame colour; where the water appeared green, the ſtones were green alſo; and where the water appeared white, the bottom was a pure white ſand.'
From the entrance to the Red Sea, at Cape Gardafu, to the Cape of Good Hope, the direc⯑tion of the coaſt is pretty equal, and the ſea forms no bays of any note. There is, indeed, a ſmall ſcoop on the coaſt of Melinda, which, if the Iſland of Madagaſcar were united to the continent, might be conſidered as a part of a large bay. This iſland, it is true, though ſepa⯑rated by the ſtraits of Mozambigue, appears to have formerly belonged to the continent; for, in this ſtrait, there are deep ſands of great ex⯑tent, eſpecially on the Madagaſcar coaſt, which make the open part of it very narrow.
From the Cape of Good Hope to Cape Negro, on the weſt coaſt of Africa, the land lies in the ſame direction; and the whole of it ſeems to be a chain of mountains: It is, at leaſt, a very elevated country, and, though more than 500 leagues in length, it it is furniſhed with no rivers of any conſideration, excepting one or two, which are, known no farther than their [311] mouths. But the coaſts, above Cape Negro, makes a large curve; and the land, along this curve, appears to be lower than that of the reſt of Africa: It is watered by ſeveral great rivers, the largeſt of which are the Coanza and the Zaire. From Cape Negro to Cape Gonſalvez, are the mouths of 24 conſiderable rivers; and the ſpace between theſe two capes, reckoning along the ſhore, is about 420 leagues. We would be tempted to think, that the ocean has encroached on theſe low lands of Africa, not by its natural motion from eaſt to weſt, which could have no influence in producing this effect, but by the facility with which it might have under⯑mined and ſurmounted them. From Cape Gon⯑ſalvez to Cape Trois-pointes, the ocean forms an open bay, which preſents nothing remark⯑able, excepting a very advanced point nearly in the middle of it, called Cape Formoſa: It like⯑wiſe contains, in the ſouthern part of it, the iſlands of Fernandpo, St Thomas, and Prince's Iſland. Theſe iſlands appear to be a continua⯑tion of a chain of mountains ſituated between Rie del Rey, and the river Jamoer. From Cape Trois-pointes to Cape Palmas, the ocean runs a little in upon the land; and from Cape Palmas to Cape Tagrin, there is nothing wor⯑thy of remark. But, beyond Cape Tagrin, there is a ſmall bay in the country of Sierra-Leona; and a little farther, there is another, in which are ſituated the iſlands of Biſagas. After [312] this we meet with Cape Verd, which projects far into the ſea, and of which the iſlands of the ſame name appear to be a continuation; or, rather, they ſeem to be a continuation of Cape Blanc, which is a more elevated country, and ſtretches ſtill farther into the ocean. We next come to a mountainous and dry coaſt, which commences at Cape Blanc, and terminates at Cape Bajador: The Canary iſlands ſeem to be a continuation of theſe mountains. Laſtly, between Africa and Portugal, is a large open bay, in the middle of which are the celebrated ſtraits of Gibraltar. The ocean pours its waters, with great rapidity, through this ſtrait into the Mediterranean. This ſea runs into the interior parts of the land near 900 leagues, and gives riſe to many objects worthy of remark. 1ſt, It has no tides that are perceptible, excepting in the Gulf of Venice; and a ſmall flux and reflux have been alledged to take place at Marſeilles and on the coaſt of Tri⯑poli. 2d, It contains many large iſlands, as Sicily, Sardinia, Corſica, Cyprus, Majorca, &c. and Italy, which is one of the moſt extenſive peninſula's in the world: It is likewiſe adorned with a rich Archipelago, or rather, it is from the Mediterranean Archipelago that all other collec⯑tions of iſlands have acquired that appellation. But this Archipelago appears to belong more properly to the Black Sea than to the Mediter⯑ranean; and it is probable, that the country of Greece was partly covered with the Black Sea, [313] which runs into the ſea of Marmora, and from that into the Mediterranean.
It has been alledged, that a double current runs through the Straits of Gibraltar; one ſupe⯑rior, which carries the water from the ocean in⯑to the Mediterranean, and another inferior, which carries the waters from the Mediterrane⯑an back to the ocean. But this notion is falſe, and contrary to the known laws of hydroſtatics. Theſe oppoſite currents have been aſcribed to ſeveral other ſtraits, as the Boſphorus, the ſtraits of the Sund, &c.; and Marſilli has related ma⯑ny experiments tending to prove the exiſtence of a ſuperior and inferior current in the Boſ⯑phorus. Theſe experiments, however, muſt have been fallacious; for ſuch a phaenomenon is repugnant to the nature and motion of fluids. Beſide, Greaves, in his Pyramidographie, has de⯑monſtrated, by accurate experiments, that there are no oppoſite currents in the Boſphorus. Mar⯑ſilli and others may have been deceived by the regorging of the water near the ſhores, which takes place in the Boſphorus, in the ſtraits of Gibraltar, and in all rapid rivers, and which oft⯑en produces a motion oppoſite to that of the principal current.
Let us now briefly run over the coaſts of the New Continent. We ſhall begin with Cape Hold-with-hope, which is ſituated in the 73d degree of North Latitude. This is the moſt northerly point of land in New Greenland, and [314] is diſtant from Cape North in Lapland about 160 or 180 leagues. From this cape the coaſt of Greenland might be traced to the polar circle, where the ocean forms a large ſtrait between Iceland and Greenland. Some maintain, that this country in the neighbourhood of Iceland is not the Antient Greenland, formerly poſſeſſed by the Danes as a province dependent on that kingdom; its inhabitants were civilized Chriſti⯑ans, who had biſhops, churches, and a number of towns proportioned to their trade. The Danes had a communication with them as eaſy, and as frequent, as the Spaniards with the Canary iſlands: There ſtill exiſts, it is ſaid, laws and regulations reſpecting the government of this province, and theſe not of a very antient date. However, without forming any conjectures how this country came to be abſolutely loſt, we find not, in New Greenland, the leaſt veſtige of what is here related. They are mere ſavages: They have no buildings: There is not a word in their language that has the ſmalleſt affinity to the Daniſh tongue; and there is not a ſingle cir⯑cumſtance from which we can infer it to be the ſame country. It is even almoſt a deſert, and is covered with ſnow and ice the greateſt part of the year. But, as theſe lands are of vaſt ex⯑tent, and, as the coaſts have been little frequent⯑ed by modern navigators, they may have miſ⯑ſed the place occupied by the deſcendents of theſe poliſhed people; or the increaſe of the ice [315] in this ſea may now, perhaps, prevent all acceſs to them. If, however, maps can be truſted, the whole coaſt of this country is known: It forms a large peninſula, at the extremity of which are the two ſtraits of Frobiſher and of Frieſland, where the cold is exceſſive, although they are not farther north than the Orkneys, that is, a⯑bout 60 degrees.
Between the weſt coaſt of Greenland, and that of Labrador, the ocean forms a gulf, and then a large mediterranean, which is the coldeſt of all ſeas, and its coaſts are little known. In purſuing this gulf, we meet with Davis's ſtrait, which leads to the Chriſtian ſea, which termi⯑nates in Baffin's bay, through which there ap⯑pears to be an outlet into Hudſon's bay. The ſtrait of Cumberland, which, like that of Davis, may lead into the Chriſtian ſea, is more narrow and more ſubject to be frozen. Hudſon's ſtrait, though much farther ſouth, is alſo frozen for ſome part of the year: And it is remarkable, that the tides are very high in theſe ſeas and ſtraits, although no tides take place in the inland ſeas of Europe, as the Baltic and Mediterranean. This difference ſeems to be occaſioned by the motion of the ſea from eaſt to weſt, which pro⯑duces high tides in ſtraits oppoſite to the current of the waters, or whoſe mouths open to the eaſt. Whereas, in thoſe of Europe, which open to the weſt, there are no tides. The ocean, by its ge⯑neral movement, ruſhes into the former, but [316] from the latter; and this is the reaſon why the tides are ſo violent in the ſeas of China, Corea, and Kamtſchatka.
In ſailing down Hudſon's bay towards La⯑brador, there is a narrow opening, which Davis, in 1586, traverſed for about 30 leagues, and traded with the inhabitants. But no attempts have hitherto been made to diſcover the whole of this arm of the ſea. We know nothing of the neighbouring country, but the land of the Eſquimaux. Fort Pon-chartrin is the only ſet⯑tlement, and the moſt northerly part of this country; and it is ſeparated from the iſland of Newfoundland by the ſmall ſtrait of Belleiſle, which is little frequented. As the eaſtern coaſt of Newfoundland has the ſame direction with that of Labrador, this iſland appears to have been formerly a part of the continent, in the ſame manner as Iſle-Royal ſeems to have been detached from Acadia. The bottoms of the great bank, and of the leſſer banks on which the cod-fiſhery is carried on, are not deep; but, as they ſhelve a great way under water, they pro⯑duce violent currents. Between Cape Breton and Newfoundland, there is a pretty large ſtrait, which is the mouth of a ſmall mediterranean, called the Gulf of St Laurence. It ſends off a branch, which extends a conſiderable way into the country, and appears to be only the mouth of the river of that name. In this arm of the ſea the tides are very perceptible; and, even at [317] Quebec, which is farther up the country, the waters riſe ſeveral feet. Leaving the gulf of St Laurence, and following the coaſt of Acadia, we meet with a ſmall gulf called Boſton-Bay, which is of a ſquare figure, and advances but a little way into the land. But, before we purſue this coaſt any farther, it is worthy of remark, that, from Newfoundland to Guiana, the ocean forms an immenſe bay, that runs in upon the land as far as Florida, which is more than 500 leagues. This bay is ſimilar to that of the Old Con⯑tinent above deſcribed, where the ocean, af⯑ter forming a large gulf between Kamtſchatka and New Britain, gives riſe to a great mediter⯑ranean, which comprehends the ſeas of Kamt⯑ſchatka, of Corea, of China, &c. In the ſame manner, in the New Continent, the ocean, after forming a large gulf between Newfoundland and Guiana, gives riſe to a great mediterranean, extending from the Antilles to Mexico; which confirms what we have advanced concerning the motion of the ſea from eaſt to weſt: For it ap⯑pears that the ocean has gained as much territory on the eaſt of America as on the eaſt coaſt of Aſia. Beſides, theſe great gulfs in each con⯑tinent lie under the ſame degrees of latitude, and are nearly of equal extent. Such ſingular relations, it would appear, muſt have been pro⯑duced by the ſame cauſe.
If we examine the poſition of the Antilles, beginning with the iſland of Trinidad, which is [318] the ſouthmoſt, it is impoſſible to doubt but that Trinidad, Tobago, the Granades, St Vincent, Martinico, Marygalante, Antego, Barbadoes, and all the adjacent iſles, once formed a chain of mountains which extended from ſouth to north, like Newfoundland and the country of the Eſquimaux. Farther, the direction of the Antilles from eaſt to weſt, if we begin with Bar⯑badoes, and paſs on to St Bartholomy, Porto-Rico, St Domingo, and Cuba, is nearly the ſame with the coaſts of Cape Breton, Acadia, and New England. All theſe iſlands lie ſo cloſe to⯑gether, that they may be regarded as a continued belt of land, and as the moſt elevated parts of a country now occupied by the ſea. Moſt of them, in effect, are nothing but the tops of mountains; and the ſea between them and the continent is a true mediterranean, in which the tides are not much more perceptible than in our Mediterra⯑nean, although the ſtraits between the iſlands are directly oppoſite to the motion of the ſea from eaſt to weſt, which ſhould contribute to raiſe the tides in the gulf of Mexico. But, as this gulf is very broad, the waters elevated by the tide, being expanded over a large ſurface, hardly produce any ſenſible change upon the coaſt of Louiſianna and ſeveral other places.
Both the Old and New Continents, therefore, appear to have been encroached upon by the ocean in the ſame latitudes: Both are furniſhed with a great mediterranean, and a vaſt number [319] of iſlands, which likewiſe lie nearly in the ſame latitudes. The only difference is, that the Old Continent, being much larger than the New, has a mediterranean on its weſt coaſt, to which the New Continent has nothing analogous. But both ſeem to have undergone ſimilar revolutions; theſe revolutions are greateſt near their middle parts, or between the tropics, where the motion of the ſea is moſt violent.
The coaſts of Guiana, from the mouth of the river Oronoko to that of the Amazones, offer nothing remarkable. But the Amazones, which is the largeſt river in the univerſe, forms a con⯑ſiderable ſheet of water near Coropa, before it diſcharges itſelf into the ſea by the two mouths which ſorround the iſland of Caviana. From the mouth of the Amazones to Cape St Roche, the river runs almoſt ſtraight eaſt; from Cape St Roche to Cape St Auguſtine, it runs ſouth; and from Cape St Auguſtine, to the bay of All Saints, it runs weſtward in ſuch a manner that this part of Braſil projects conſiderably into the ocean, which is directly oppoſite to a ſimilar projection of the African coaſt. The bay of All Saints is a ſmall arm of the ſea, which ad⯑vances about 50 leagues into the land, and is much frequented by navigators. From this bay, to Cape St Thomas, the coaſt runs ſtraight ſouth, and from thence, in a ſouth-weſt direction, to the mouth of the Plata, where an arm of the ſea projects about 100 leagues into the land. [320] From this river, to the ſouthern extremity of America, the ocean forms a large bay, which is terminated by Falkland Iſland, Cape Aſſumption, and other lands bordering on Terra del Fuego. At the bottom of this bay is the ſtrait of Magel⯑lan, the longeſt in the univerſe, and where the tides riſe very high. Beyond this is the ſtrait of La Maire, which is much ſhorter; and, laſtly, Cape Horn, which is the ſouth point of Ame⯑rica.
On the ſubject of points or head-lands, it is remarkable, that they all regard the ſouth, and that moſt of them are cut by ſtraits that run from eaſt to weſt. The point of South America regards the Arctic Pole, and it is cut by the ſtrait of Magellan: That of Greenland, which like⯑wiſe has a ſouthern aſpect, is cut from eaſt to weſt by the ſtrait of Frobiſher: That of Afri⯑ca regards alſo the ſouth, and, beyond the Cape of Good Hope, are banks and ſhoals which ap⯑pear to have been ſeparated from it: That of the peninſula of India is cut by the ſtrait be⯑tween it and iſland of Ceylon; and, like all others, projects ſouthward. Theſe are facts; but we are unable to give any explication of them.
From Terra del Fuego, all along the weſt coaſt of South America, the ocean makes conſiderable advances into the land; and this coaſt ſeems to follow exactly the direction of the high moun⯑tains which traverſe this part of the continent [321] from ſouth to north, from the Equator to the Arctic Pole. Near the Line, the ocean forms a large bay, extending from Cape St Francois to Panama, that famous iſthmus, which, like that of Suez, prevents the junction of the two ſeas. If theſe two necks of land were removed, both the Old and the New Continent would be di⯑vided into two diſtinct portions. From Panama to California, there occurs nothing worthy of remark. Between the peninſula of California and New Mexico, is a long arm of the ocean, called the Vermilion Sea, which is more than 200 leagues long. In fine, the weſt coaſt of Cali⯑fornia has been traced to the 43d degree of la⯑titude. It was in this latitude that Drake, who firſt diſcovered the land to the north of Califor⯑nia, and which he called New Albion, was o⯑bliged, by the rigour of the cold, to change his courſe, and to anchor in a ſmall bay which bears his name; ſo that the countries beyond the 43d or 44th degree, in this part of the globe, are as little known as thoſe of North America beyond the 48th degree, which is inhabited by the Moozemleki, and the 51ſt, which is inha⯑bited by the Aſſiniboils; the territory of the for⯑mer ſavages extends much farther weſt than that of the latter. All beyond, for 1000 leagues in length, and as much in breadth, is totally un⯑known, unleſs the Ruſſians, as they pretend, have made ſome diſcoveries by departing from [322] Kamtſchatka, and viſiting the eaſtern coaſts of North America.
The ocean, then, ſurrounds the whole globe, without interruption, and we may ſail round it by taking our departure from the ſouth point of America. But we are ſtill uncertain whether the ocean ſurrounds, in the ſame manner, the north part of the globe; and all the navigators, who have attempted to go from Europe to Chi⯑na by the north-eaſt or north-weſt, have equally failed in their enterpriſes.
Lakes differ from mediterraneans; the former derive no water from the ocean; on the con⯑trary, when they communicate with ſeas, they are conſtantly diſcharging water into them. Thus the Black Sea, which ſome geographers have regarded as a branch of the Mediterranean, and, of courſe, as an appendage of the ocean, is only a lake; becauſe, in place of receiving any ſupplies from the Mediterranean, its waters run with rapidity through the Boſphorus, in the lake called the Sea of Marmora, and from thence through the ſtraits of the Dardanelles into the Grecian Sea. The Black Sea is about 250 leagues long, and 100 broad: It receives a number of large rivers, as the Danube, the Nieper, the Don, the Boh, the Donjec, &c. The Don, which unites with the Donjec, before it arrives at the Black Sea, forms a lake called the Palus Meotis, which is more than 100 leagues in length, and from 20 to 25 in breadth. The Sea [323] of Marmora, which is below the Black Sea, is a lake ſmaller than the Palus Meotis, being not above 50 leagues long, and 8 or 9 broad.
It is related by ſome of the antients, and par⯑ticularly by Diodorus Siculus, that the Euxine, or Black Sea, was originally a great river or lake, and had no communication with the Greek Sea; but that its waters were, in the courſe of time, ſo greatly augmented by the rivers that fall into it, that they forced a paſſage, firſt by the iſlands of Cyanea, and then by the Helle⯑ſpont. This opinion has great probability on its ſide; and, I think, it is no difficult matter to explain how the operation was effected: For, ſuppoſing the bottom of the Black Sea to have been formerly much lower than it is now, the mud and ſand carried down by the rivers would gradually raiſe it, till the ſurface of the water was elevated above that of the land, and then the water would neceſſarily find a paſſage for itſelf: And, as the rivers continue ſtill to tranſ⯑port ſand and earth, and as, at the ſame time, the quantity of water in the rivers diminiſhes in proportion as the mountains from which they ſpring are lowered, it may happen, in the courſe of ages, that the Boſphorus will again be filled up. But, as effects of this nature depend on many cauſes, we muſt content ourſelves with ſimple conjectures. Mr Tourneſort, on the au⯑thority of the antients, ſays, that the Black Sea, which receives the waters of a great part of Eu⯑rope [324] and Aſia, after being conſiderably augment⯑ed, opened to itſelf a paſſage by the Boſphorus, and either formed the Mediterranean, or in⯑creaſed its waters to ſuch a degree, that they forced a paſſage to the ocean through the ſtraits of Gibraltar; and that the iſland of Atalantis, mentioned by Planto, was, on this occaſion, total⯑ly overflowed. This notion cannot be ſupport⯑ed; for the ocean runs into the Mediterranean, and not the Mediterranean into the ocean. Be⯑ſides, M. Tournefort has not combined two eſ⯑ſential facts, though he has mentioned both of them. The firſt is, that the Black Sea receives 9 or 10 rivers, each of which furniſhes more water than is diſcharged by the Boſphorus; and the ſecond, that the Mediterranean does not re⯑ceive more water from rivers than the Black Sea, though it be ſeven or eight times larger; and what it receives from the Boſphorus is not the tenth part of what falls into the Black Sea. How, therefore, could this tenth part of the water that falls into a ſmall ſea, produce not on⯑ly a larger ſea, but augment its waters to ſuch a degree as would enable it to break down the [...] of Gibraltar, and overwhelm an iſland of [...] extent than the whole of Europe? It is [...] to perceive that M. Tournefort has not ſufficiently conſidered this matter. The Mediterranean derives from the ocean at leaſt ten times the quantity of water it receives from the Black Sea; for the narroweſt part of the [325] Boſphorus exceeds not 800 pace, while that of the ſtraits of Gibraltar is more than 5000; and, ſuppoſing the velocities of both to be equal, ſtill the water in the ſtraits of Gibraltar is by much the deepeſt.
M. Tournefort, who ridicules Polybius for predicting that the Boſphorus will in time be filled up, has not attended ſufficiently to circum⯑ſtances, otherwiſe he would not have pronoun⯑ced the impoſſibility of ſuch an event. Muſt not the Black Sea, which conſtantly receives the ſand and mud of eight or ten large rivers, gra⯑dually fill up? Muſt not the winds and the na⯑tural current of the waters continually tranſport part of theſe matters into the Boſphous? It is, therefore, extremely probable, that, in the courſe of ages, the Boſphorus will be choaked up, when the quantity of water diſcharged by the rivers into the Black Sea ſhall be greatly diminiſhed. Now, the rivers are diminiſhing daily, becauſe the mountains, which collect the dews, and give riſe to the rivers, are continually diminiſhing.
The Black Sea receives more water from ri⯑vers than the Mediterranean; and Mr Tourne⯑fort obſerves, on this ſubject, 'That the greateſt rivers in Europe fall into this ſea by means of the Danube, into which are diſcharged the ri⯑vers of Subia, Franconia, Bavaria, Auſtria, Hungary, Moravia, Corinthia, Croatia, Both⯑nia, Servia, Tranſylvania, and Wallachia: The rivers of Black Ruſſia and of Podolia fall like⯑wiſe [326] wiſe into the ſame ſea by means of the Nieſter; thoſe of the ſouthern and eaſtern parts of Po⯑land, of the northern part of Muſcovy, and of the country of the Coſſacks, fall into it, either by the Nieper or Boriſthenes; the Tanais and the Copa empty themſelves into the Black Sea by the Cimmerian Boſphorus; the rivers of Mingrelia, the principal of which is the Phaſis, alſo diſcharge their contents into this ſea, and likewiſe the Caſalmac, the Sangaris, and other rivers of Aſia Minor which take a northern courſe: Theſe vaſt diſcharges notwithſtanding, the Thracian Boſphorus, which is the only out⯑let from the Black Sea, is not comparable to any one of theſe great rivers*.'
All theſe facts demonſtrate the great quantity of water carried off by evaporation; and it is owing to this circumſtance that the ocean con⯑ſtantly runs into the Mediterranean by the ſtraits of Gibraltar. It is difficult to aſcertain the quan⯑tity of water received by any ſea; it requires an exact knowledge of the breadth, depth, and ve⯑locity of all the rivers that fall into it, of their augmentation and diminution in different ſea⯑ſons of the year; and of the quantity which the ſea loſes by evaporation. This laſt is the moſt difficult to determine; for, ſuppoſing evapora⯑tion to be proportioned to the ſurfaces, it will be greater in a warm than in a cold climate. Beſides, water mixed with ſalt and bitumen eva⯑porates [327] more ſlowly than freſh water; a ſea ſub⯑ject to great agitations evaporates more quickly than a calm ſea; and a difference in the depth has alſo ſome effect. In fine, ſo many particu⯑lars are included in the theory of evaporation, that it is not poſſible to make an exact eſtima⯑tion of it.
The water of the Black Sea is leſs clear, and leſs ſalt than that of the ocean. There are no iſlands in it; and its tempeſts are more violent and more dangerous than thoſe of the ocean; becauſe its waters, being extended in a baſin which has but an inconſiderable outlet, move, when agitated, in a kind of whirlpools, which beat upon all ſides of a veſſel with an inſupport⯑able violence*.
After the Black Sea, the greateſt lake in the world is the Caſpian Sea, which extends from ſouth to north about 300 leagues, and its mean breadth exceeds not 50. This lake receives the Wolga, beſides ſeveral other conſiderable rivers, as the Kur, the Faie, and the Gempo. But, what is ſingular, it receives not one river from the eaſt coaſt; the country on that ſide is a ſan⯑dy deſert, which remained, till lately, altogether unknown. The Czar Peter I. ſent engineers to make a chart of the Caſpian Sea. It had been repreſented as round by former geographers; but it is very long and very narrow. Its eaſt⯑ern coaſt, and the neighbouring country, were [328] entirely unknown; even Lake Aral, which is about 100 leagues eaſt of the Caſpian, was ei⯑ther not known to exiſt, or was conſidered as a part of this ſea. Thus, before the diſcoveries of the Czar, there was in this region an un⯑known country of 300 leagues in length, and 100 or 150 in breadth. Lake Aral is nearly oblong, and about 90 or 100 leagues long, and 50 or 60 broad. It receives the Sideroias and the Oxus, two large rivers; but, like the Caſ⯑pian, it has no outlet for diſcharging its waters; and, as the Caſpian receives no rivers from the eaſt, Lake Aral, on the contrary, receives none from the weſt. Hence it is preſumable, that theſe two formerly conſtituted but one lake; and the rivers being gradually choaked up, the country between them would neceſſarily be co⯑vered with ſand. There are ſome ſmall iſlands in the Caſpian; and its waters are much freſher than thoſe of the ocean. Storms, in this ſea, are ex⯑ceedingly dangerous; and it affords not navi⯑gation to large veſſels, on account of ſhoals, ſand-banks, and rocks concealed under the ſur⯑face. 'The largeſt veſſels employed on the Caſpian,' ſays Pietro della Valle* 'along the coaſts of the province of Mazanda in Perſia, where ſtands the town of Ferhabad, although they be called ſhips, are no better than our tar⯑tanes: Their ſides are high; they draw little wa⯑ter, and are flat-bottomed. They are built of this [329] conſtruction, not only becauſe this ſea is ſhal⯑low near the coaſts, but becauſe it is full of ſhoals and ſand-banks; ſo that no other veſſels could be uſed with ſafety. I was ſurpriſed to ſee no fiſhing carried on at Ferhabad, ex⯑cepting ſalmons at the mouth of the river, a bad kind of ſturgeon, and other freſh water fiſhes of no value. I attributed this to their ignorance of navigation and of the art of fiſh⯑ing, till I was informed by the Cham of Eſter⯑abad, that this ſea, at the diſtance of 20 or 30 miles from the ſhore, is ſo ſhallow, that nets could not be uſed with advantage; and that the ſame reaſon accounted for the conſtruction of their veſſels, which carry no cannon, becauſe the Caſpian is not infeſted with pirates.'
Struys, Avril, and others, affirm, that, in the neighbourhood of Kilan, there are two gulfs, which ſwallow up the waters of the Caſpian, and carry them, by ſubterraneous paſſages, into the Perſic Gulf. De Fer, and other geographers, have laid down theſe gulfs in their maps, though we are aſſured by the Czar's envoys, that they have no exiſtence*. The fact, with regard to the willow leaves found on the Perſic Gulf, and which are alledged by the ſame au⯑thors to be tranſported from the Caſpian Sea, becauſe no willows grow near the Perſic Gulf, appears to be equally improbable as the ſubter⯑raneous paſſages, which Gemelli Careri, as well [330] as the Ruſſians, maintain to be altogether ima⯑ginary. Beſides, the Caſpian is about a third leſs than the Black Sea, which laſt alſo receives more water by rivers; evaporation, therefore, is a⯑lone ſufficient to carry off all its adventitious wa⯑ters, without the aſſiſtance of imaginary gulfs, or ſubterraneous paſſages.
There are lakes, or ſeas, which neither re⯑ceive nor diſcharge rivers; there are others which both receive and diſcharge; and others which only receive rivers. The Caſpian, Lake Aral, and the Dead Sea, are of the laſt kind: In Aſia Minor, there is a ſmall lake of the ſame ſpecies: There is another ſtill larger in Perſia, upon which the city of Marago is ſituated: It is of an oval figure, and about 10 or 12 leagues long, and 6 or 7 broad: It receives the Tauris, which is not a very conſiderable river. If to theſe we add a ſmall lake of the ſame nature in Greece, 12 or 15 leagues from Lepanto, we have an enumeration of all the known lakes in Aſia that belong to this ſpecies. In Europe, there is not a ſingle one of any conſideration. There are ſeveral ſmall lakes of this kind in Africa, as thoſe which receive the rivers Ghir, Zez, Touguedout, and Tafilet. Theſe four lakes lie at no great diſtance from one another, and are ſituated on the frontiers of Barbary, near the deſart of Zaara. There is another in the province of Kovar, which receives the river that runs through the country of Berdoa. In [331] North America, which abounds with lakes, there are none of this kind, excepting two ſmall col⯑lections of water formed by brooks, the one near Guatimapo, and the other ſome leagues from Realnuevo, both in Mexico. But in Peru there are two contiguous lakes, one of which, Lake Titicaca, is very large, and receives a river which riſes near Cuſco; but no river iſſues from it. There is a ſmall one in Tucuman, which receives the river Salta; another, in the ſame country, of greater extent, receives the Santiago; and three or four between Tucuman and Chili.
Theſe lakes, which neither receive nor give riſe to any river, are more numerous than the kind juſt mentioned. They are a kind of ſwamps, which collect the rain water; or, they may originate from ſubterraneous waters, which iſſue in the form of ſprings in low grounds, from which there is no fall to carry them off. Thoſe rivers that overflow may alſo leave ſtag⯑nating waters upon the land, which remain a conſiderable time, and are occaſionally recruited by ſubſequent inundations. Salt lakes may ſometimes be produced by inundations from the ſea, as that at Harlem, and ſeveral others, in Holland, to which no other origin can be aſcri⯑bed. The ſea, likewiſe, by abandoning certain lands, may have left lakes in the low grounds of particular countries, and which continue to be maintained by the rains. Of this kind, there [332] are ſmall lakes in Europe, as in Ireland, in Jut⯑land, in Italy, in the country of the Griſons, in Poland, in Muſcovy, in Finland, and in Greece: But all theſe are of little conſideration. In Aſia, near the Euphrates, in the deſart of Irac, there is one above 15 leagues long; another in Perſia, nearly of the ſame extent, upon which are ſituated the towns of Kelat, Tetuan, Vaſtan, and Van; a ſmall one in Chorazan, near Fer⯑rior; another in Independent Tartary, called Lake Levi; two in Muſcovite Tartary; one in Cochinchina; and, in ſine, a pretty large one not far from Nankin. This laſt, however, Communicates with the neighbouring ſea by a canal of conſiderable extent. In Africa, there is a ſmall lake of this ſpecies in the kingdom of Morocco; another near Alexandria, which ap⯑pears to have been left by the ſea; another, 8 or 10 leagues long, formed by the rain-water, in the deſart of Azarad, about the 30th degree of latitude; another, ſtill larger, upon which is ſituated the town of Gaoga, under the 27th de⯑gree; another, but much ſmaller, near the town of Kanum, under the 30th degree; one near the mouth of the river Gambia; ſeveral others in Congo, about the 2d or 3d degree of ſouth lati⯑tude; two others in the country of the Caffres; one of them, called Lake Ruſumbo, is not very extenſive; and the other, which lies in the pro⯑vince of Arbuta, is perhaps the largeſt of this kind, being about 25 leagues long, and 7 or [333] 8 broad: There is likewiſe one of theſe lakes near the eaſt coaſt of Madagaſcar, about the 29th degree of ſouth latitude.
In America, there is one of theſe lakes ſitua⯑ted in the middle of the peninſula of Florida, which has an iſland called Serrope in its centre. The lake near the town of Mexico, which is round, and about 10 leagues in diameter, belongs likewiſe to this ſpecies. There is another ſtill more extenſive in New Spain, about 25 leagues from the eaſtern coaſt of the bay of Campeachy; and another, of ſmaller dimenſions, in the ſame country, near the coaſt of the South Sea. Some travellers have affirmed, that, in the interior parts of Guiana, there is a very large lake of this ſpecies, which they call Golden Lake, or Lake Parima; and they have given marvellous accounts of the riches of the neighbouring coun⯑try, and of the great quantities of gold duſt found in this lake, which they alledge to be more than 400 leagues in length, and above 125 in breadth; no river, it is ſaid, either en⯑ters into, or iſſues from it. Though this lake be laid down in ſeveral maps, its exiſtence is ſtill problematical.
But the moſt common and the moſt extenſive lakes are thoſe which both receive and give riſe to rivers: As they are exceedingly numerous, I ſhall only mention the largeſt, or the moſt re⯑markable, of them. Beginning with Europe, we have, in Switzerland, the Lake of Geneva, [334] that of Conſtance, &c. In Hungary, Lake Ba⯑laton, and another, of equal extent, in Livonia, which ſeparates this province from Ruſſia; Lake Lapwert in Finland, which is very long, and divides into ſeveral branches, and Lake Oula, which is of a circular figure: In Muſcovy, Lake Ladoga, which is more than 25 leagues long, and above 12 broad; Lake Onega, which is e⯑qually long, but leſs in breadth; Lake Ilmen; Lake Belozero, which is one of the ſources of the Wolga; Lake Iwan-Oſero, which is one of the ſources of the Don; and two other lakes, from which the river Vitzogda derives its origin: In Lapland, the lake from which iſſues the river Kimi; another much larger, and ſituated near the coaſt of Wardhus; and ſeveral others of leſs note, which give riſe to the rivers Lula, Pitha, and Uma: In Norway, two lakes nearly of the ſame dimenſions with thoſe of Lapland: In Sweden, Lake Vener, which is as large as Lake Meller, upon which Stockholm is ſituated; and two leſs conſiderable, one near Elvedal, and the other near Lincopin.
In Siberia and in Muſcovite and Independent Tartary, there are a great number of theſe lakes, of which the principal are, the great lake Bara⯑ba, which is more than 100 leagues long, and of which the waters fall into the Irtis; the great lake Eſtraguel the ſource of the Irtis; ſeveral leſſer ones, the ſources of the Jeniſca; the great lake Kita, the ſource of the Oby; another great [335] lake, the ſource of the Angara; Lake Baical, which is more than 70 leagues long, and is formed by the river Angara; and Lake Pehu, the ſource of the Urack, &c. In China and Chineſe Tartary, we have Lake Dalai, the ſource of the great river Argus, which falls into the Amour; the lake of the Three Mountains, the ſource of the river Helum, which falls likewiſe into the Amour; the lakes of Cinhal, Cokmor, and Sorama, the ſources of the river Hoamho; two large lakes in the neighbourhood of Nankin, &c. In Tonquin is the Guadag, a lake of con⯑ſiderable magnitude. In India, we have Lake Chiamat, which is the ſource of the river La⯑quia, and lies near the ſources of the Ava, the Longenu, &c. This lake is more than 50 leagues long, and about 40 broad. The ſource of the Ganges is another lake; and one near Caſh⯑mire gives riſe to the Indus, &c.
In Africa there are Lake Cayar, and two or three others, near the mouth of the Senegal; Lake Guarda, and Lake Sigiſmus, which, toge⯑ther, make a triangular lake of 100 leagues long, and 75 broad, and contain a conſiderable iſland. It is in this lake that the Niger loſes its name, and, at its exit, aſſumes that of Senegal. In a⯑ſcending towards the courſe of this river, we meet with another pretty large lake called Bour⯑nou, where the Niger again changes its name; for the river that falls into this lake is called Gombaru. At the ſources of the Nile in Aethio⯑pia, [336] is the great lake Gambia, which is above 50 leagues long. On the coaſt of Guiney are alſo ſeveral lakes, which appear to have been o⯑riginally formed by the ſea; and there are few others in Africa of any conſideration.
North America is the country of lakes. The moſt extenſive of them are, Lake Superior, which is about 125 leagues long, and 50 broad; Lake Huron, which is near 100 leagues in length, and about 40 in breadth; Lake Illionois, which, comprehending the bay of Puants, is nearly as extenſive as Lake Huron; Lake Erie and Lake Ontario, which together, exceed 80 leagues in length, by 20 or 25 in breadth; Lake Miſtaſin, to the north of Quebec, is about 50 leagues long; Lake Champlain, to the ſouth of Quebec, is nearly of equal length; Lake Alemipigon, and Lake Chriſtinaux, both to the north of Lake Superior, are likewiſe conſiderable; the Lake of the Aſſmiboils contains ſeveral iſlands, and is more than 75 leagues long: Beſides the Mexi⯑con Gulf, there are two conſiderable lakes in that country; that called Nicaragua, in the pro⯑vince of the ſame name, is about 70 leagues in length.
Laſtly, in South America, there is a ſmall lake, the ſource of the Maragnon; a more ex⯑tenſive one gives riſe to the river Paraguay: There are, beſides Lake Titicares, the waters of which fall into the river Plata; two leſſer ones, which diſcharge their waters into the ſame ri⯑ver; [337] and ſome inconſiderable ones in the inte⯑rior parts of Chili.
All lakes that give riſe to rivers, and all thoſe which occur in the courſe of rivers, or which border upon and diſcharge their waters into ri⯑vers, are not ſalt. Almoſt all thoſe, on the con⯑trary, which receive rivers, but give riſe to none, are ſalt. This circumſtance ſeems to favour the opinion, that the ſaltneſs of the ſea is occaſioned by the ſalts brought down from the land by the rivers; for we find ſalt does not evaporate; and, of courſe, all that is tranſported by the rivers remains in the ſea: Although the water of ri⯑vers appears to be freſh, it is well known, that it contains a ſmall quantity of ſalt, which, in the courſe of ages, might accumulate to ſuch a de⯑gree as would be ſufficient to produce the pre⯑ſent ſaltneſs of the ſea, and which muſt be con⯑tinually augmenting. It is in this manner, I preſume, the Caſpian, Lake Aral, and the Black Sea, have become ſalt. With regard to thoſe ſeas, which, like marſhes, or ſwamps, neither receive nor diſcharge rivers, they are either ſalt or freſh, according to their origin. Thoſe in the neighbourhood of the ſea are commonly ſalt; and thoſe at a diſtance from it are freſh; becauſe the former have originated from an in⯑undations of the ſea, and the latter from freſh fountains.
The waters of the Dead Sea contain a great deal of the bitumen of Judea, which is nothing but [338] aſphaltes; and, accordingly, this ſea is often termed the Aſphaltic Lake. The neighbouring land is impregnated with this bitumen: And many have imagined, like the Lake Avernus, no fiſh could live in it, and that birds were ſuf⯑focated in attempting to fly over it. But ſuch diſmal effects are produced by neither of theſe lakes; for both of them contain fiſhes, the birds fly over them in ſafety, and men bathe in them with impunity.
It is ſaid, that, in Bohemia, there is a lake, which has holes in it ſo deep, that they cannot be ſounded, and that, from theſe holes, there iſſue violent winds which ſweep over all Bohe⯑mia, and, in winter, raiſe into the air maſſes of ice of more than 100 pounds weight*. We are likewiſe told of a petrifying lake in Iceland; and Lake Neagh in Ireland poſſeſſes the ſame quality. But theſe petrifications are, doubtleſs, nothing but incruſtations ſimilar to thoſe pro⯑duced by the waters at Arcueil.
WATER, like other fluids, naturally de⯑ſcends from the higher to the lower grounds, if not prevented by ſome interpoſed obſtacle; and, after it has occupied the loweſt ſituation, it remains ſmooth and tranquil, unleſs diſturbed by ſome foreign cauſe. All the wa⯑ters of the ocean are collected in the loweſt pla⯑ces upon the ſurface of the earth; and hence the motions of the ſea muſt proceed from cauſes that are external. The chief motion is that of the tides, which riſe and fall alternately, and from which reſults a general and perpetual mo⯑tion, in all ſeas, from eaſt to weſt. Theſe two motions have an invariable relation to the mo⯑tions [340] of the moon. During the full and new moons, this motion from eaſt to weſt is moſt re⯑markable, as well as that of the tides, which ebb and ſlow, upon moſt coaſts, every 6½ hours: It is always high tide when the moon arrives at the meridian, either above or below the horizon of the place; and it is always ebb or low tide when the moon is at the greateſt diſtance from the meridian, or when it riſes and ſets. The motion from eaſt to weſt is perpetual; becauſe, when the tide is riſing, the whole ocean moves from eaſt to weſt, and puſhes weſtward an im⯑menſe body of water; and the ebbing, or reflux, appears only to be owing to the ſmaller quan⯑tity of water which is then impelled towards the weſt. The flux, therefore, ought rather to be regarded as a ſwelling, and the reflux as the [...] of the waters, which, in place of di⯑ſturbing the motion from eaſt to weſt, is the cauſe which produces and renders it perpetual; though this motion, for the reaſon already men⯑tioned, is greater during the flux than the re⯑flux.
This motion is attended with the following circumſtances: 1ſt, It is more ſenſible at the full and new moon than at the quadratures; it is likewiſe more violent in ſpring and autumn than in any other ſeaſon; and it is weakeſt at the fol⯑ſtices. This phaenomenon in occaſioned by the combined attractions of the moon and ſun. 2d, The direction and quantity of this motion [341] is often varied by the winds, eſpecially ſuch as blow conſtantly from the ſame quarter. Great rivers, in like manner, by diſcharging their wa⯑ter into the ſea, produce currents which often extend ſeveral leagues, and are ſtrongeſt when the direction of the wind correſponds with the general motion. Of this an example is afforded in the Pacific Ocean, where the motion from eaſt to weſt is conſtant, and very perceptible. 3d, It is worthy of remark, that, when one part of a fluid is moved, the motion is communicated to the whole: During the tides, therefore, a great part of the ocean is ſenſibly put in mo⯑tion; and, conſequently, the whole ocean, from ſurface to bottom, is moved at the ſame time.
To render this more clear, let us attend to the cauſes which produce the tides. We formerly remarked, that the moon acted upon the earth by a force which ſome call attraction, and others gravity. This force penetrates the whole globe, is exactly proportioned to the quantity of mat⯑ter, and decreaſes as the ſquares of the diſtances increaſe. Let us next examine what effects this force muſt produce upon the waters when the moon comes to the meridian of any place. The ſurface of the water immediately under the moon is then nearer that planet than any other part of the earth; of courſe, that part of the ſea muſt be elevated towards the moon, and the ſummit of this eminence muſt be oppoſite to the moon's center. To produce this eminence, the [342] waters upon the ſurface, as well as thoſe at the bottom, contribute their ſhare, in proportion to their diſtances from the moon, which acts upon them in the inverſe ratio of the ſquares of their diſtances. Thus the ſurface of this part of the ſea is firſt elevated; the ſurface of the adjacent parts is likewiſe elevated, but in a ſmaller de⯑gree; and the waters at the bottom of all theſe parts are raiſed by the ſame cauſe. Hence, as the whole portion of water under the moon is raiſed, the waters at a diſtance, upon which no attraction is exerted, muſt neceſſarily ruſh for⯑ward with precipitation to ſupply the place of thoſe which were elevated, or drawn towards the moon. It is in this manner that the flux, or high tide, is produced, which is more or leſs ſenſible on different coaſts, and which agitates the ſea, not only at the ſurface, but at the great⯑eſt depths. The reflux, or ebb, is a conſequence of the natural diſpoſition of the water, which, when no longer acted upon by the moon, ſub⯑ſides, and returns to occupy thoſe ſhores from which it had been forced to retire by a foreign power. The ſame effect is produced when the moon arrives at the antipode, or oppoſite meri⯑dian, but for a different reaſon: In the firſt caſe, the waters riſe, becauſe they are nearer the moon than any other part of the globe; and, in the ſe⯑cond, they riſe, becauſe the moon is at the greateſt diſtance from them. It is eaſy to perceive that the effect muſt be the ſame; for, the waters here be⯑ing [343] leſs attracted than thoſe of the oppoſite he⯑miſphere, they will neceſſarily recede, and form an eminence, the higheſt point of which will be where the attraction is leaſt, that is, in the me⯑ridian oppoſite to the moon's ſtation, or to the place where ſhe was thirteen hours before. When the moon comes to the horizon, the tide is ebb, and the ſea is in its natural ſtate of equi⯑librium. But, when ſhe is in the oppoſite meri⯑dian, this equilibrium cannot exiſt; for the wa⯑ters, at the place oppoſite to the moon, being then at their great diſtance from her, they are leſs attracted than the reſt of the globe; and hence their relative gravity, by which they are conſtantly kept in equilibrium, puſhes them to⯑wards the point oppoſite to the moon, in order to preſerve this equilibrium. Thus, in both caſes, when the moon is in the meridian of a place, or in the oppoſite meridian, the waters muſt be elevated nearly to the ſame height; and, conſequently, they muſt ebb or flow back when the moon is in the horizon, either at her riſing or ſetting. A motion, ſuch as we have de⯑ſcribed, neceſſarily agitates the whole maſs of the ocean, from its ſurface to its bottom; and, as the bottom is leſs affected by winds than the ſurface, the motion produced in the former, by the tides, is more regular and uniform.
From this alternate ebbing and flowing, there reſults, as already remarked, a conſtant motion of the ſea from eaſt to weſt; for the moon, [344] which is the cauſe of the tides, moves from eaſt to weſt, and, by acting ſucceſſively in this di⯑rection, ſhe draws the waters after her. This motion is moſt perceptible in ſtraits. At the ſtraits of Magellan, for example, the tides riſe near 20 feet, and they continue at this height ſix hours; but the reflux, or ebbing, laſts only two hours, and the waters run to the weſt*. This inconteſtibly proves, that the reflux is not equal to the flux, and that, from both, there re⯑ſults a motion to the weſt, which is ſtronger du⯑ring the flux than the reflux. It is for this rea⯑ſon, that, in open ſeas, at great diſtances from land, the tides are only rendered perceptible by this general current of the waters from eaſt to weſt.
The tides are much higher between the tro⯑pics than in any other part of the ocean. They likewiſe riſe higher in places that ſtretch from eaſt to weſt, in long and narrow bays, and upon coaſts which are interrupted with iſlands and promontories. The higheſt known tides take place at one of the mouths of the Indus, where they riſe 30 feet perpendicular. They have al⯑ſo a remarkable elevation at Malaya, in the ſtraits of the Sund, in the Red Sea, in Nelſon's bay, at the mouth of the river St Laurence, up⯑on the coaſts of China and Japan, at Panama, in the gulf of Bengal, &c.
[345] The ſea's motion, from eaſt to weſt, is moſt obſervable in particular places. Voyagers have often remarked it in ſailing from India to Ma⯑dagaſcar and Africa. It moves alſo with conſi⯑derable force in the Pacific ocean, and between the Moluccas and Brazil: But it is moſt violent in ſtraits: The waters are carried from eaſt to weſt, through the ſtraits of Magellan, for ex⯑ample, with ſuch rapidity, that their motion is perceptible, at a great diſtance, in the Atlantic ocean. It was this circumſtance, it is ſaid, that made Magellan conjecture that a ſtrait exiſted by which there was a communication with the two ſeas. In the ſtraits formed by the Manillas, in the channels between the Maldiva iſlands, and in the gulf of Mexico, between Cuba and Juca⯑tan, there is a conſtant current from eaſt to weſt. This motion, in the gulf of Paria, is ſo violent, that its ſtrait is called the Dragon's Mouth. It is likewiſe violent in the ſea of Canada, in that of Tartary, and in Waigait's ſtraits, through which it forces enormous maſſes of ice into the northern ſeas. The Pacific ocean runs from eaſt to weſt through the ſtraits of Japan; the ſea of Japan runs towards China; and the Indian ocean runs weſtward through the ſtraits of Java, and other iſlands of India. It is, therefore, evi⯑dent, that the ſea has a general and uniform motion from eaſt to weſt; and, it is certain, that the Atlantic runs towards America, and that the [346] Pacific ocean flies from it, as is apparent at Cape Current between Lima and Panama*.
In fine, the tides riſe and fall alternately in ſix hours and a half upon moſt coaſts, though they happen at different hours, according to the climate, and the poſition of particular lands. Thus the coaſts of the ſea are perpetually beat by the waves; and each tide carries off from the higher grounds ſmall quantities of matter, and depoſites them, at a diſtance, on the bottom of the ocean. In the ſame manner, each tide car⯑ries in, and depoſites upon low coaſts, ſand, ſhells, and other ſea-bodies, which gradually form horizontal ſtrata, and give riſe to downs, and little hills, ſimilar to other hills, both in their figure and internal ſtructure. Thus the ſea is conſtantly encroaching upon high coaſts, and loſing ground upon thoſe that are low.
To give an idea of the violent effects of a ſtormy ſea againſt a high coaſt, I ſhall relate a fact atteſted by an eye-witneſs, a perſon worthy of the higheſt credit. In the largeſt of the Ork⯑ney iſlands, there are coaſts compoſed of ſolid rock, above 200 feet high, and nearly perpendi⯑cular to the ſurface of the water. The tides, as is uſual in iſlands and promontories, riſe very high at this place. But, when a violent wind concurs with the flow of the tide, the agitation of the waters is ſo great, that they often riſe a⯑bove theſe rocks, and fall down in the form of [347] rain: Nay, to this amazing height, gravel, and ſtones as large as a man's fiſt, are raiſed from the foot of the rocks.
I myſelf ſaw, in the port of Livourne, where the ſea is much more tranquil, a tempeſt in De⯑cember 1731, which obliged the mariners to cut off the maſts of their veſſels, which were driven, by the violence of the wind, from their anchors in the road: The waters of the ſea ſur⯑mounted fortifications of a great height; and, as I was upon one of the moſt advanced works, before I could reach the town, I was more drenched with ſea-water than I could have been by the heavieſt rain.
Theſe examples may convey a notion of the violence with which the ſea acts againſt particu⯑lar coaſts. This conſtant agitation gradually wears*, corrodes, excavates, and diminiſhes the quantity of the land. All theſe materials are tranſ⯑ported and depoſited in places where the ſea is more tranquil. In the time of ſtorms, the water is foul and muddy, by the admixture of matters detached from the coaſts and from the bottom of the ſea. Theſe bodies, which are very vari⯑ous, and carried from great diſtances, are thrown [348] upon the low ſhores, eſpecially after tempeſts, as ambergris on the weſt of Ireland, yellow am⯑ber upon the coaſts of Pomerania, cocoas upon the coaſts of India, &c. and ſometimes pumice, and other ſingular ſtones. On this occaſion, we may quote a paſſage from the New Voyages to the iſlands of America. 'When at St Domingo,' ſays the author, 'I was preſented, among other things, with ſome light ſtones, brought in by the ſea in high ſouth winds: Some of them were two and a half feet long, 18 inches broad, and about a foot thick; and yet they weighed not above five pounds. They were as white as ſnow, harder than pumice, of a fine grain, and appeared not to be porous. When, how⯑ever, they were thrown into water, they re⯑bounded like a foot-ball thrown againſt the ground. It was difficult to force them under water with the hand. I incloſed two of theſe ſtones with thin boards, and found that they bore 160 pounds without ſinking. They ſer⯑ved my negro for a ſhallop on which he divert⯑ed himſelf in failing about the quay*.' This ſtone muſt have been a pumice of a cloſe fine grain, which had been tranſported by the ſea from the neighbourhood of ſome volcano, in the ſame manner as ambergris, cocoas, common pu⯑mice, the ſeeds of plants, reeds, &c. are tranſ⯑ported. It is chiefly on the coaſts of Ireland and of Scotland that obſervations of this kind have been made. The ſea, by its general mo⯑tion [349] from eaſt to weſt, ought to carry to Ameri⯑ca the productions of our coaſts; and, it muſt be by the operation of ſome irregular move⯑ments, that the productions of the Eaſt and Weſt Indias, and of the northern regions, are brought upon our coaſts. The winds are probably the cauſe of thoſe effects. In open ſeas, and at great diſtances from land, large portions of the water have been ſeen totally covered with pumice⯑ſtones. They could only come from volcano's in iſlands, or on the continent; and they have probably been tranſported to the open ſeas by currents. Before the ſouth part of America was diſcovered, and when it was not believed that the Indian ocean had any communication with ours, appearances of this kind firſt gave riſe to the ſuſpicion that ſuch a communication was not impoſſible.
The alternate motion of the tides, and the uniform motion of the ſea from eaſt to weſt, exhibit different appearances in different climates, according to the different indentations in the land, and the height of the coaſts. In ſome places the motion from eaſt to weſt is not per⯑ceptible; at others, it moves in a contrary direc⯑tion, as on the coaſt of Guiney. But theſe con⯑trary motions are occaſioned by the winds, by the poſition of the land, by the waters of great rivers, and by the diſpoſition of the bottom of the ſea. All theſe cauſes produce currents, which often change the direction of the general [350] movement. But, as this motion from eaſt to weſt is the greateſt, moſt general, and conſtant, it ought to produce the moſt ſignal effects; and, upon the whole, the ſea muſt gradually gain ground on the weſt, and loſe it on the eaſt; and, although, upon coaſts where the weſt wind blows during the greateſt part of the year, as in France and Britain, the ſea may gain land on the eaſt; yet theſe exceptions deſtroy not the effect of the general cauſe.
THE coaſts of the ſea may be divided into three kinds: 1. High coaſts com⯑poſed of hard rocks, commonly perpendicular, and of a conſiderable elevation, riſing ſome⯑times to the height of 700 or 800 feet. 2. Low coaſts, of which ſome are almoſt level with the ſurface of the water, and others have a ſmall elevation, and are often bordered with rocks nearly of a level with the water, which give riſe to breakers, and render the approach of ſhips exceedingly dangerous. 3. Downs, or coaſts formed by ſand, either accumulated by the ſea, or brought down and depoſited by rivers: Theſe [352] downs form hills of more or leſs elevation, ac⯑cording to circumſtances.
The coaſts of Italy are lined with marble and rocks of different ſpecies. Thoſe rocks ap⯑pear at a diſtance like perpendicular pillars of marble. The coaſts of France, from Breſt to Bourdeaux, conſiſt almoſt entirely of rocks on a level with the ſea, which occaſion breakers. The coaſts of England, of Spain, and of many other places, are bordered with rocks and hard ſtones, excepting particular ſpots which are em⯑ployed as roads and harbours.
The depth of the water along the coaſts is generally proportioned to their elevation; a high coaſt indicates a deep water; and, on low coaſts, the water is commonly ſhallow. The inequa⯑lities at the bottom of the ſea near the coaſts likewiſe correſpond with the inequalities in the ſurface of the ground along the ſhore. This ſubject is illuſtrated in the following manner by a celebrated voyager.
'I have made it my general obſervation, that, where the land is fenced with ſteep rocks and cliffs againſt the ſea, there the ſea is very deep, and ſeldom affords anchor-ground; and, on the other ſide, where the land falls away with a declivity into the ſea, (although the land be extraordinary high within,) yet there are com⯑monly good ſoundings, and conſequently an⯑choring; and, as the viſible declivity of the land appears near, or at the edge of the water, [353] whether pretty ſteep, or more ſloping, ſo we commonly find our anchor-ground to be more or leſs deep or ſteep; therefore we come near⯑er the ſhore, or anchor farther off, as we ſee convenient; for there is no coaſt in the world, that I know, or have heard of, where the land is of a continual height, without ſome ſmall vallies or declivities, which lie intermixed with the high land. They are the ſubſiding of val⯑lies or low lands, that make dents in the ſhore and creeks, ſmall bays, and harbours, or little coves, &c. which afford good anchoring, the ſurface of the earth being there lodged deep under water. Thus we find many good har⯑bours on ſuch coaſts, where the land bounds the ſea with ſteep cliffs, by reaſon of the de⯑clivities, or ſubſiding of the land between theſe cliffs: But, where the declenſion from the hills or cliffs is not within land, between hill and hill, but, as on the coaſt of Chili and Peru, the declivity is toward the main ſea, or into it, the coaſt being perpendicular, or very ſteep from the neighbouring hills, as in thoſe countries from the Andes, that run along the ſhore, there is a deep ſea, and few or no harbours or creeks. All that coaſt is too ſteep for anchor⯑ing, and hath the feweſt roads fit for ſhips of any coaſt I know. The coaſts of Gallicia, Portugal, Norway, and Newfoundland, &c. are coaſts like the Peruvian, and the high iſlands of the Archipelago; but yet not ſo [354] ſcanty of good harbours; for, where there are ſhort ridges of land, there are good bays at the extremities of thoſe ridges, where they plunge into the ſea; as on the coaſt of Ca⯑raccos, &c. The iſland of John Ferdinando, and the iſland of St Helena, &c. are ſuch high land with deep ſhore: And, in general, the plunging of any land under water, ſeems to be in proportion to the riſing of its continuous part above water, more or leſs ſteep; and it muſt be a bottom almoſt level, or very gently declining, that affords good anchoring, ſhips being ſoon driven from their moorings on a ſteep bank; therefore, we never ſtrive to anchor where we ſee the land high, and bounding the ſea with ſteep cliffs; and, for this reaſon, when we came in ſight of States-Iſland, near Terra del Fuego, before we entered into the South-Seas, we did not ſo much as think of anchor⯑ing after we ſaw what land it was, becauſe of the ſteep cliffs which appeared againſt the ſea; yet there might be little harbours or coves for ſhallops, or the like, to anchor in, which we did not ſee, or ſearch after.'
'As high ſteep cliffs bounding on the ſea have this ill conſequence, that they ſeldom af⯑ford anchoring; ſo they have this benefit, that we can ſee them far off, and fail cloſe to them, without danger; for which reaſon we call them bold ſhores; whereas low land, on the contrary, is ſeen but a little way, and in many [355] places we dare not come near it, for fear of running a-ground before we ſee it. Beſides, there are, in many places, ſhoals thrown out by the courſe of great rivers, that from the low land fall into the ſea.'
'This which I have ſaid, that there is uſually good anchoring near low lands, may be illu⯑ſtrated by ſeveral inſtances. Thus, on the ſouth ſide of the bay of Campeachy, there is moſtly low land, and there alſo is good an⯑choring all along ſhore; and, in ſome places to the eaſtward of the town of Campeachy, we ſhall have ſo many fathom as we are leagues off from land; that is, from 9 or 10 leagues diſtance, till you come within 4 leagues; and from thence to land it grows but ſhallower. The bay of Honduras alſo is low land, and con⯑tinues moſtly ſo, as we paſſed along from thence to the coaſts of Portobel, and Cartagena, till we came as high as Santa Martha; afterwards the land is low again, till you come towards the coaſt of Caraccos, which is a high coaſt and bold ſhore. The land about Surinam, on the ſame coaſt, is low and good anchoring, and that over on the coaſt of Guinea is ſuch alſo. And ſuch, too, is the bay of Panama, where the pilot-book orders the pilot always to ſound, and not to come within ſuch a depth, be it by night or day. In the ſame ſeas, from the high land of Guatimala in Mexico, to California, there is moſtly low land and good anchoring. [356] In the main of Aſia, the coaſt of China, the bay of Siam and Bengal, and all the coaſt of Coromandel, and the coaſt about Malacca, and againſt it the iſland of Sumatra, on that ſide, are moſtly low anchoring ſhores. But, on the weſt ſide of Sumatra, the ſhore is high and bold; ſo moſt of the iſlands lying to the eaſtward of Sumatra; as the iſlands Borneo, Celebes, Gilolo, and abundance of iſlands of leſs note, lying ſcattering up and down thoſe ſeas, are low land, and have good anchoring about them; with many ſhoals ſcattered to and fro among them; but the iſlands lying againſt the Eaſt-Indian Ocean, eſpecially the weſt ſides of them, are high land and ſteep, particularly the weſt parts, not only of Sumatra, but alſo of Java, Timor, &c. Particulars are endleſs; but, in general, 'tis ſeldom but high ſhores and deep waters, and, on the other ſide, low land and ſhallow ſeas are found together*.'
It is, therefore, fully eſtabliſhed by the obſer⯑vations of navigators, that there are, in the bot⯑tom of the ſea, conſiderable mountains, and o⯑ther inequalities. We are alſo aſſured by the teſtimony of divers, that there are ſmaller ine⯑qualities occaſioned by rocks, and that the cold is greateſt in the hollows or valleys. In general, as formerly remarked, the depths of open ſeas [...] in proportion to their diſtance from the coaſts. It appears, from M. Buache's chart of that part of the ocean which lies be⯑tween [357] the coaſts of Africa and America, and from the draughts he has given us of the ſea from Cape Tagrin to Rio-grand, that the bot⯑tom of the ocean is as irregular as the ſurface of the land; that Abrolhos, where there are vigies, and where ſome of the rocks are on a level with the water, are only the tops of large and high mountains, of which Dolphin iſland is one of the moſt elevated points; that the Cape de Verd iſlands are likewiſe the tops of moun⯑tains; and that all round theſe abrolhos and iſlands, the depth of the ſea is unfathomable.
With regard to the qualities of the different ſoils at the bottom of the ſea, little can be ſaid with preciſion, as all our knowledge is derived from ſounding and from divers. We on⯑ly know, that ſome places are covered with ſlime and mud of a conſiderable thickneſs, in which anchors can have no hold: It is proba⯑ble that, in theſe places, the mud is depoſited by rivers. Other parts are covered with ſand of different kinds, ſimilar to thoſe upon land. In others are heaps of ſhells, madrepores, corals, and other productions of inſects, juſt beginning to unite and to aſſume the form of ſtones: In others, we find fragments of ſtones, gravel, and frequently ſtones and marbles compleatly from⯑ed. In the Maldiva iſlands, for example, they build their houſes with a hard ſtone raiſed from ſome fathoms under water. At Marſeilles very good marble is raiſed from the bottom of the [358] ſea, which is ſo far from waſting or deſtroying ſtones and marble, that, as ſhall be proved in our diſcourſe on minerals, it creates and preſerves them: It is the ſun, the earth, the air, and the rains, which alone corrupt and deſtroy theſe ſubſtances.
The bottom of the ſea muſt be compoſed of the ſame materials as the ſurface of the earth which we inhabit, ſince the very ſame ſubſtan⯑ces are found on both. At the bottom of ſome parts of the ocean are vaſt collections of ſhells, madrepores, and corals; and we find, upon land, numberleſs quarries, banks of chalk, and of other ſubſtances, mixed with the ſame ſhells, madrepores, and corals; ſo that, in every view, the dry parts of this globe reſemble thoſe cover⯑ed with the waters, both in compoſition of ma⯑terials, and in ſuperficial inequalities.
To theſe inequalities at the bottom, we muſt aſcribe the origin of currents; for, if the bot⯑tom were uniform and level, there could be no current but the general motion from eaſt to weſt, and ſuch as might occaſionally be produ⯑ced by the winds. But what inconteſtibly proves, that moſt currents are produced by the tides, and take their direction from inequalities at the bottom, is, that they uniformly follow the tides, and change their courſe at every ebb and flow*. This is confirmed by the teſtimony [359] of all navigators, who unanimouſly affirm, that, in thoſe places where the tides are moſt impetu⯑ous, the currents are likewiſe moſt rapid.
Thus it is apparent, that the tides give riſe to currents, and that they always follow the di⯑rection of the oppoſite hills or mountains be⯑tween which they run. Currents produced by winds likewiſe obſerve the direction of the emi⯑nences concealed under the waters; for they ſeldom run in the direct path of the winds; nei⯑ther do thoſe produced by the tides invariably obſerve the courſe pointed out by their original cauſe.
To give a diſtinct idea of the origin of cur⯑rents, let it be remarked, that they take place in all ſeas; that ſome are rapid, and others ſlow; that ſome are of great extent both in length and breadth, and others ſhorter and nar⯑rower; that the ſame cauſe by which they are produced, whether it be the wind or the tides, frequently beſtows on each a difference both in celerity and direction; that a north wind, for example, which ought to produce a general mo⯑tion towards the ſouth, gives riſe, on the con⯑trary, to a number of ſeparate currents, very different both in their direction and extent, ſome running ſouth, others ſouth-eaſt, and others ſouth-weſt; ſome are rapid, others ſlow; ſome long and broad, and others ſhort and narrow: In a word, their motions are ſo various and combined, that they loſe all reſemblance to their [360] general cauſe. When a contrary wind blows, every motion is uniformly reverſed; and the courſe of the different currents is preciſely the ſame as would neceſſarily take place between two oppoſite and neighbouring hills upon the ſurface of the land, were it covered with water. Of this, the Maldiva and Indian iſlands, where the winds blow and the currents run regularly for ſix months in oppoſite directions, afford moſt ſtriking examples. The ſame thing has been remarked of currents between ſhoals and ſand⯑banks. In general, all currents, from whatever cauſe they proceed, have the ſame dimenſions and the ſame direction through their whole courſe; but they differ greatly from each other in every reſpect. This uniformity and variety can proceed from no other cauſe but the ine⯑qualities of the hills, mountains, and vallies, at the bottom of the ocean; for, it is an eſtabliſh⯑ed fact, that the current between two iſlands follows the direction of the coaſts; and the ſame phaenomenon is exhibited between ſhoals and ſand-banks. The hills and mountains in the ſea, therefore, may be conſidered as the banks which contain and direct the currents: Hence a current is a river, the breadth of which is determined by that of the valley through which it runs; its rapidity is proportioned to the force by which it is produced, combined with the breadth of the interval through which it paſſes; and its direction is marked out by the [361] poſition of the hills and other inequalities be⯑tween which it ſhapes its courſe.
An opportunity is now afforded us of ex⯑plaining that ſingular correſpondence between the angles of hills and mountains, which is ob⯑ſervable in every country of the world. We have already remarked this uniform correſpon⯑dence of angles in the banks of rivers. The cauſe of this effect depends on the laws of hy⯑droſtatics, and might be eaſily explained. But it is ſufficient for our preſent purpoſe, that the fact is general, and univerſally known; and every man may ſatisfy himſelf with his own eyes, that, when the bank of a river projects in⯑to the land, to the left, for inſtance, the oppo⯑ſite bank, on the contrary, makes a projection from the land on the right.
The currents of the ocean, therefore, which ought to be regarded as large rivers, and as ſub⯑ject to the ſame laws as thoſe on land, muſt, like them, have formed, through the whole ex⯑tent of their courſe, many ſinuoſities or wind⯑ings with correſponding angles or projections: And, as the banks of currents are hills and mountains, either above or below the ſurface of the water, they muſt have produced on theſe eminences the ſame effects as our rivers do up⯑on their banks. Thus, we have no longer any reaſon to be aſtoniſhed, that our hills and mountains, which were formerly covered with [362] the ſea, and formed by the ſediments of its wa⯑ters, ſhould have aſſumed, by the motion of its currents, this regular figure, ariſing from the correſpondence of their oppoſite angles. They were originally banks of currents, or of ſea-ri⯑vers, and neceſſarily muſt have aſſumed a figure and direction ſimilar to thoſe of land-rivers.
This alone, independent of the other proofs which we have adduced, is a ſufficient demon⯑ſtration that all our preſent continents and iſlands were formerly covered with the waters of the ocean, and throws much light on the theory which I have been endeavouring to eſta⯑bliſh. It was not enough to have proved that the internal ſtrata of the earth were formed by ſediments of the waters; that the mountains were elevated by ſucceſſive accumulations of theſe ſediments; or, that many ſtrata were impreg⯑nated with ſhells and other productions of the ſea. It was ſtill neceſſary to inveſtigate and aſſign the real cauſe of the correſpondence in the angles of mountains, which hitherto had never been attempted, but which, when united with the other proofs, forms a connected chain of evidence in ſupport of my theory, as com⯑pleat as the nature of phyſical reaſoning will admit.
The moſt conſpicuous currents of the ocean are thoſe in the Atlantic near the coaſt of Gui⯑ney. They extend from Cape Verd to the bay of Fernandopo. They run from weſt to eaſt, [363] which is contrary to the general motion of the ſea; and they are ſo rapid, that veſſels ſail in two days from Moura to Rio de Benin, about 150 leagues, but require ſix or ſeven weeks to return. It would even be impoſſible to clear theſe latitudes, were it not by means of the tem⯑peſtuous winds which ſuddenly ariſe in them: But there are ſometimes whole ſeaſons in which the mariner is obliged to remain ſtationary, on account of perpetual calms, the ſea having here no motion but what it derives from the currents; and theſe always run in upon the coaſts, from which they extend not above 20 leagues. Near the iſland of Sumatra, there are rapid currents, which run from ſouth to north, and which have probably given riſe to the bay between Malacca and India. We find ſimilar currents between Java and the lands of Magellan, and between the Cape of Good Hope and Madagaſcar, eſpe⯑cially on the African coaſt from Natal to the Cape. In the Pacific ocean, upon the coaſts of Peru, and the reſt of America, the waters move from ſouth to north, which is probably owing to the conſtant blowing of the ſouth wind. The ſame motion from ſouth to north has been re⯑marked on the coaſts of Braſil, from Cape St Auguſtine to the Antilles, and from the mouth of the Manilla ſtraits to the Philippines and Japan*.
[364] There are violent currents in the neighbour⯑hood of the Maldiva iſlands; and between theſe iſlands, as already obſerved, the currents run al⯑ternately in oppoſite directions ſix months in the year, and are probably occaſioned by the trade⯑winds.
We only here enumerate ſuch currents as are remarkable both for their extent and their rapi⯑dity; becauſe the number of leſſer currents is almoſt infinite. The tides, the winds, and every cauſe that agitates the waters, produce currents, which are more or leſs perceptible in different places. We have already remarked, that the bottom of the ſea is, like the land, interſected with mountains and vallies, ſhoals and ſand⯑banks. In all the mountainous places, the cur⯑rents muſt neceſſarily be violent; and, where the bottom is ſmooth and level, they are almoſt imperceptible; for the rapidity of a current muſt augment in proportion to the obſtacles the water meets with. The current between two chains of mountains will be more or leſs violent in proportion to their diſtance. The ſame thing muſt happen between two banks of ſand, or two adjacent iſlands. It is, accordingly, remarkable, that, in the Indian ocean, which is interſected with an innumerable quantity of iſlands and ſand-banks, there are every where currents, which, by their rapidity, render navigation ex⯑tremely dangerous.
[365] Currents are not only occaſioned by inequa⯑lities at the bottom; but a ſimilar effect is pro⯑duced by the coaſts, from which the waters are repelled to greater or leſs diſtances. This re⯑gorging of the waters may be rendered perpe⯑tual and violent by particular circumſtances: An oblique poſition, for example, of a coaſt, its con⯑tiguity to a bay or a great river, a promontory, or any particular obſtacle to the general move⯑ment of the waters, will always give riſe to a current: Now, as nothing is more irregular than the bottom and the coaſts of the ſea, the num⯑ber of currents that every where appear ought not to create ſurpriſe.
All currents have a determinate breadth, pro⯑portioned to the interval between the two emi⯑nences which limit them. They run in the ſame manner as land-rivers; they form a channel, and cut their banks in a regular manner, with correſponding angles: In fine, the currents of the ocean have ſcooped out our valleys, ſhaped our mountains, and beſtowed upon the land, while it remained under the ſurface of the wa⯑ters, the form under which it now appears.
If any doubt ſhould remain concerning the correſpondence in the angles of mountains, I appeal to the teſtimony of every man's obſerva⯑tion. Every traveller may remark this corre⯑ſpondence in oppoſite hills. When a hill makes a projection to the right, the oppoſite one uni⯑formly recedes to the left. Beſides, in oppoſite [366] hills ſeparated by vallies, there is rarely any dif⯑ference in their height. The more I obſerve the contours and elevations of hills, I am the more convinced of the correſpondence of their angles, and of their reſemblance to the channels and banks of rivers. It was the repeated obſer⯑vation of this ſurpriſing regularity and reſem⯑blance that firſt ſuggeſted the idea of the theory of the earth which I am now ſupporting. When to this are added the paralleliſm of the ſtrata, and the ſhells ſo univerſally incorporated with different materials, no ſubject of this nature can admit of a greater degree of probability.
IN our climates, nothing can appear to be more capricious and irregular than the force and direction of the winds. But there are ſome countries where this irregularity is not ſo great, and others where the wind blows conſtantly in the ſame direction, and with nearly the ſame de⯑gree of force.
Though the motions of the air depend on many cauſes; yet there are ſome more con⯑ſtant and powerful than others; but it is diffi⯑cult to eſtimate their preciſe effects, becauſe theſe are often modified by ſecondary cauſes.
[368] The heat of the ſun is the moſt powerful cauſe of winds: It produces a conſiderable and ſucceſſive rarefaction in the different parts of the atmoſphere, and gives riſe to an eaſt-wind, which blows conſtantly between the Tropics, where the rarefaction is greateſt.
The force of the ſun's attraction upon the at⯑moſphere, and even that of the moon, are in⯑conſiderable, when compared with the cauſe juſt mentioned. This force it is true, produces a motion in the air ſimilar to that of the tides in the ſea: But, though the air is elaſtic, and 800 times lighter than water, the motion pro⯑duced by attraction cannot exceed what is ex⯑cited in the waters of the ocean by the ſame cauſe; for the action of gravity being propor⯑tioned to the quantity of matter, it muſt elevate a ſea of water, of air, or of quickſilver, nearly to the ſame height. Hence the influence of the planets upon the air muſt be inconſiderable*; and, though it muſt occaſion a ſlight motion from eaſt to weſt, this motion becomes alto⯑gether inſenſible when compared with that pro⯑duced by the heat of the ſun: But, as the rare⯑faction is always greateſt when the ſun is in the zenith, the current of air muſt follow the courſe of the ſun, and produce a conſtant wind from eaſt to weſt. This wind blows perpetually at ſea in the Torrid Zone, and at land, in moſt [369] places between the Tropics. It is this wind which we perceive when the ſun riſes; and, in general, eaſt winds are more frequent, and more violent than weſt winds. The general wind, from eaſt to weſt, extends even beyond the Tropics. It blows ſo conſtantly in the Pacific ocean, that the ſhips coming from Acapulco to the Philippines, perform their voyage, which is more than 2700 leagues, without the leaſt dan⯑ger, and without, almoſt, the neceſſity of being directed. In the Atlantic, between Africa and Braſil, this wind is equally conſtant. It is like⯑wiſe felt between the Philippines and Africa; but there it is leſs conſtant, on account of the obſtacles it meets with from the numerous iſlands in that ſea; for it blows, during the months of January, February, March, and April, between the Mozambique coaſt and India; but it gives place to other winds during the reſt of the year: And, though it is leſs perceptible on the coaſts than on the open ſea, and ſtill leſs in the interior parts of continents than on the coaſts, yet, in ſome places, it blows almoſt per⯑petually, as on the eaſt coaſts of Braſil, on the coaſts of Loango in Africa, &c.
This wind is conſtant under the Line; and, therefore, in going from Europe to America, mariners direct their courſe ſouthward, along the coaſts of Spain and Africa, till they come within 20 degrees of the Equator, where they fall in with the eaſt, or trade-wind, which car⯑ries [370] them directly to the coaſt of America. By means of the ſame wind, the voyage from Aca⯑pulco to the Philippines is performed in two months; but the return from the Philippines to Acapulco is much more difficult, and requires a longer time. About 28 or 30 degrees on this ſide of the Line, the weſt wind is equally conſtant; and, for this reaſon, the veſſels return⯑ing from the Weſt Indies to Europe, obſerve not the ſame rout as in going out. Thoſe from New Spain run north along the coaſt till they arrive at the Havannah, in the iſland of Cuba; and from thence they proceed northward till they fall in with the weſt wind, which carries them to the Azores, and then to Spain. In the ſame manner, veſſels returning by the South Sea from the Philippines or China, to Peru or Mexico, ſail north as far as Japan; and, under that latitude, they ſail to within a certain diſtance from California; and from thence, following the coaſt of New Spain, they arrive at Acapulco. Theſe eaſt winds blow not always from the ſame point; but, in general, they blow from the ſouth-eaſt from April to September, and from the north-eaſt from November to April.
The eaſt wind, by its conſtant action, aug⯑ments the general motion of the ſea from eaſt to weſt. It alſo produces perpetual currents, ſome of them running from eaſt to weſt, and others from eaſt to ſouth-eaſt, or north-weſt, ac⯑cording to the direction of the eminences, or [371] chains of mountains, below the ſurface, the vallies or intervals between which ſerving as channels to theſe ſea-rivers. The variable winds, which blow ſometimes from the eaſt, and ſometimes from the ſouth, likewiſe produce currents, which change their direction with that of the wind.
The winds that blow conſtantly for ſome months are commonly ſucceeded by contrary winds, which obliges the mariner to wait for that which is moſt favourable to his deſtination. When theſe winds change, they often produce, for ſeveral days, and ſometimes for a month, or even two months, a perfect calm, or dreadful tempeſts.
Theſe general winds, occaſioned by the ra⯑refaction of the atmoſphere, are variouſly com⯑bined and modified by different cauſes, and in different climates. In that part of the Atlantic which lies under the Temperate Zone, the north wind blows almoſt conſtantly during the months of October, November, December, and January. Theſe months, therefore, are moſt favourable for ſhips going to the Indies, which are carried over the Line by this wind: And it is a well known fact, that veſſels which depart from Eu⯑rope in March, frequently arrive not ſooner at Braſil than thoſe which ſet out in the following October. The north wind reigns almoſt perpe⯑tually, during the winter, off Nova Zembla, and other northern coaſts. At Cape de Verd, the [372] ſouth wind blows, during the month of July, which is the rainy ſeaſon, or winter, in theſe climates. At the Cape of Good Hope, the north-weſt wind blows during the month of Septem⯑ber: The ſame wind blows at Patna in the Eaſt Indies, during the months of November, De⯑cember and January, and occaſion great rains; but the eaſt wind prevails during the other nine months. In the Indian Ocean, between Africa and India, and as far as the Molucca iſlands, the trade-wind from eaſt to weſt reigns from January to the beginning of June; the weſt winds begin in Auguſt or September; and, in the interval between June and July, there are dreadful tempeſts, generally from the north winds; but theſe winds are more variable on the coaſts than in the open ſeas.
In the kingdom of Guzarat, and upon the neighbouring coaſts, the north winds blow from March to September; and, during the other months, the ſouth winds almoſt always prevail. The Dutch, in returning from Java, ſet out in January or February, by the aſſiſtance of the eaſt wind, which is felt as far as the 18th degree of ſouth latitude; and then they meet with ſouth winds, which carry them to St Helena*.
Some regular winds are produced by the melting of the ſnows. This was remarked by the antient Greeks. During ſummer, a north-eaſt wind, and a ſouth-eaſt one during winter, [373] was obſerved to take place in Thracia, in Mace⯑donia, in the Egean Sea, and even in Egypt and Africa; and winds of the ſame kind have been remarked in Congo, at Guzarat, and at the extremity of Africa, which are all occaſioned by the melting of the ſnows. Regular winds, which laſt but a few hours, are alſo produced by the motion of the tides; and, in many places, as on the coaſts of New Spain, of Congo, of Cuba, &c. a wind blows from the land during the night, and from the ſea during the day.
The north winds are equally regular within the polar circles; but they become more and more imperceptible as we approach the Equa⯑tor: This remark is applicable to both poles.
In the Atlantic and Aethiopic ocean, within the tropics, an eaſt wind blows, through the whole year, without any conſiderable variation, excepting in ſome ſmall ſpots, where it changes according to the ſituation of the coaſts, and other circumſtances: 1ſt, Near the coaſt of Africa, and about the 28th degree of North latitude, veſſels are certain of finding a freſh gale from the north-eaſt, or north-north-eaſt, which accom⯑panies them to the 10th degree of the ſame la⯑titude, about 100 leagues from the coaſt of Guinea; and, at the 4th degree of north latitude, they meet with calms and tornadoes. 2d, In going by the Caribbee iſlands, this wind turns more and more eaſterly, in proportion as the veſſels approach the American coaſt. 3d, The [374] limits of theſe variable winds, in the Atlantic, are more extenſive upon the coaſts of America than upon thoſe of Africa. Along the coaſt of Guinea, from Sierra Leona to the iſland of St Thomas, an extent of about 500 leagues, there is a perpetual ſouth, or ſouth-weſt wind. The narroweſt part of the Atlantic is from the coaſt of Guinea to Braſil, where it is not above 500 leagues over. Veſſels, however, that depart from Guinea, are obliged to ſhape their courſe ſouthward, eſpecially when they ſet out in the months of July or Auguſt, in order to fall in with the ſouth-eaſt winds, which blow conſtant⯑ly during this ſeaſon*.
In the Mediterranean, the eaſt wind blows from the land in the evening, and the weſt wind from the ſea in the morning. The ſouth wind, which is accompanied with rain, and blows commonly during the latter end of autumn, at Paris, in Burgundy, and Champagne, yields to a mild north wind, which produces that fine weather vulgarly called Saint Martin's Sum⯑mer†.
Doctor Liſter alledges, that the eaſt wind, which reigns during the whole year between the tropics, is occaſioned by the tranſpiration of the plant called the ſea-lentil, which abounds in theſe climates; and that the difference of land⯑winds is owing to the different ſituation of trees [375] and foreſts. This ridiculous whim he aſſigns as the cauſe of the winds; and, in his opinion, the wind is ſtrongeſt at mid-day, becauſe the tranſpiration from plants is then the greateſt; and the wind, continues he, blows from eaſt to weſt, becauſe all plants are, in ſome meaſure, ſun-flowers, and tranſpire moſt from the ſide oppoſite to the ſun*.
Other authors have aſſigned the diurnal mo⯑tion of the earth as the cauſe of this eaſt wind. This notion is ſpecious: But every man, who has the leaſt knowledge of phyſics, muſt allow, that no fluid which ſurrounds the earth can be affected by its rotation; that the air muſt move along with the earth itſelf; and that the rota⯑tory motion is equally imperceptible in the at⯑moſphere, as on the ſurface of the earth.
The principal cauſe of the winds, as already remarked, is the heat of the ſun†; for, what⯑ever rarefies or condenſes the air, muſt produce a wind or current in a direction oppoſite to thoſe places where the rarefaction or condenſation is greateſt.
The preſſure of clouds, exhalations from the earth, the exploſion of meteors, rains, &c. like⯑wiſe produce conſiderable agitations in the at⯑moſphere. Each of theſe cauſes, when variouſ⯑ly combined, produce different effects. As it is in vain to attempt a compleat theory of the winds, I confine myſelf to their hiſtory.
[376] If we had a ſeries of obſervations upon the di⯑rection, the force, and the variations of the winds in the different climates of the earth, and if theſe obſervations were ſufficiently numerous and ex⯑act, we might be enabled to form more compleat ideas with regard to the cauſes of the different changes in the atmoſphere, than we at preſent poſſeſs.
The winds are more regular at ſea than upon land; becauſe their motion is not interrupted. But, upon land, the direction is often changed by the interpoſition of mountains, foreſts, cities, and other obſtacles. Winds are often reflected from mountains with a force nearly equal to that of their original current: Theſe winds are exceed⯑ingly irregular, becauſe their direction depends on the contour, the height, and the ſituation of the mountains from which they rebound. The ſea-winds alſo blow with more force and uni⯑formity, and laſt longer: The land-winds, how⯑ever violent, have intermiſſions and moments of repoſe: But, at ſea, the current of the air, ha⯑ving no obſtacles to contend with, is uniform and perpetual.
At ſea, the eaſt winds, and thoſe which come from the Poles, are generally ſtronger than the weſt winds, and thoſe that proceed from the E⯑quator. But, at land, the ſouth and weſt winds are more or leſs violent, according to the differ⯑ent ſituation of particular countries. During ſpring and autumn, the winds, both at ſea and [377] land, are more violent than in ſummer or win⯑ter. For this, ſeveral reaſons may be aſſigned: 1. In ſpring and autumn the tides are higheſt; and, conſequently, the winds they excite are moſt violent during theſe ſeaſons: 2. The mo⯑tion produced in the atmoſphere by the action of the ſun and moon, or the tides of the air, muſt likewiſe be greateſt at the equinoxial ſeaſons: 3. The melting of the ſnows in ſpring, and the condenſation of the vapours exhaled in ſummer by the ſun, and which fall down in the autumn in the form of rain, produce, or, at leaſt, aug⯑ment the force of the winds. 4. The tranſition from heat to cold, or from cold to heat, muſt create conſiderable augmentation and diminu⯑tion in the volume of the air, which alone is ſuf⯑ficient to raiſe great winds.
Contrary currents in the atmoſphere have oft⯑en been remarked. We ſee ſome clouds mo⯑ving in one direction, and others, either above or below them, proceeding in a direction per⯑fectly oppoſite. This contrariety of motion ne⯑ver continues long; becauſe its general cauſe is the reſiſtence of ſome large cloud, which reflects the wind in a direction oppoſite to its natural courſe, but is ſoon diſſipated.
The winds are more violent in proportion to the elevation of the ground, till it arrive at the ordinary ſtation of the clouds, which is about one-fourth or one-third of a league perpendi⯑cular height; and beyond this, the ſky is gene⯑rally [378] ſerene, eſpecially in ſummer, and the wind gradually diminiſhes: It is even ſaid to be alto⯑gether imperceptible on the tops of the higheſt mountains. However, as the ſummits of theſe mountains are covered with ice and ſnow, it is natural to think, that this region of the air is agitated during the fall of the ſnows, and, that the winds are only imperceptible in the ſummer ſeaſon. The light vapours which are raiſed in ſummer fall in the form of dews; but, in winter, they are condenſed, and fall on the tops of the mountains in the form of ſnow or ice, which may raiſe conſiderable winds at that altitude.
The celerity of a current of air is augmented when its paſſage is contracted. The ſame wind, which is but ſlightly felt in a large open plain, be⯑comes violent in going through a narrow paſs in a mountain, or between two high houſes; and it is moſt violent at the tops of the buildings or of the mountain, becauſe the air being compreſſed by theſe obſtacles, is augmented both in volume and denſity; and, as its celerity remains the ſame, its force or momentum muſt be increaſed. It is for this reaſon that the wind appears to be more violent near a church or a tour than at a diſtance from them. I have often remarked, that the wind reflected from a building ſtand⯑ing by itſelf is ſtronger than the direct wind which produced it. This effect can be owing to no other cauſe than the compreſſion of the air againſt the building from which it rebounds.
[379] As the denſity of the air is greateſt at the ſurface of the earth, it is natural to conclude, that the wind muſt there alſo be moſt violent; and this concluſion is, I apprehend, juſt, when the ſky is ſerene: But, when it is charged with clouds, the action of the wind will be moſt vio⯑lent at the height of the clouds, which are den⯑ſer than air, as they fall in the form of rain or of hail. In computing the force of wind, there⯑fore, we ought to eſtimate not only its veloci⯑ty, but likewiſe the denſity of the air; for, two winds of equal velocities may differ greatly in their force, if the denſities of the air be unequal. From this remark, we may learn the imperfec⯑tion of thoſe machines which have been em⯑ployed for meaſuring the velocity of the winds.
Particular winds, whether they be direct or reflected, are more violent than thoſe that are general. The interrupted action of land-winds depends on the compreſſion of the air, which renders every blaſt more violent than if the cur⯑rent were uniform. A uniformly continued ſtream of air produces not ſuch havock as the fury of thoſe winds which blow, as it were, by paroxyſins. But of this we ſhall treat more fully in the next article.
The winds, in their various directions, may be conſidered under general points of view, from which, perhaps, ſome uſeful deductions may be drawn. For example, the winds may be divided into Zones. The eaſt wind, which [380] extends 25 or 30 degrees on each ſide of the Equator, exerts its force round the globe within the Torrid Zone. The north wind blows with equal conſtancy in both the Frigid Zones. Thus, the eaſt wind occupies the Torrid Zone, and the north wind the Frigid Zones. With regard to the Temperate Zones, the winds peculiar to them may be conſidered only as currents of air, produced by the combination of the two princi⯑pal winds, which gives riſe to all thoſe that come from the eaſtern points; and the weſt winds, which are common in the Temperate Zones, both in the Pacific and Atlantic Oceans, may be conſidered as reflections from the con⯑tinents of Aſia and America, but deriving their origin principally from the eaſt and north winds.
Though we have ſaid, that, generally ſpeak⯑ing, the eaſt wind blows round the globe 25 or 30 degrees on each ſide of the Equator; yet it muſt be acknowledged, that, in ſome places, it extends not ſo far, and that its direction is not throughout from eaſt to weſt; for, on this ſide of the Equator, it is eaſt-north-eaſt, and, beyond the Equator, it is eaſt-ſouth-eaſt, and, the more we recede from the Equator, its direction is the more oblique. The Equator is the line under which the direction of the wind from eaſt to weſt is moſt exact. In the Indian Ocean, for example, the general wind from eaſt to weſt ex⯑tends not above 15 degrees beyond the Equator. In going from Goa to the Cape of Good Hope, [381] this wind is not felt beyond the 12th degree of ſouth latitude, nor is it perceptible on this ſide of the Equator. But, after arriving at the 12th degree of ſouth latitude, this wind continues to the 28th degree. In the ſea which ſeparates A⯑frica from america, there is an interval from the 4th degree of north latitude to the 10th or 11th of ſouth latitude, where this general wind is not perceived. But, beyond the 10th or 11th de⯑gree, it extends to the 30th.
There are likewiſe many deviations in the trade-winds, which have an alternate motion. Some continue for a longer or ſhorter time; o⯑thers have a greater or leſſer extent; others are more or leſs regular, and more or leſs violent. The following, according to Varenius, are the principal phaenomena of theſe winds. 'In the ocean between Africa and India, and as far as the Molucca iſlands, the eaſt wind commences in January, and continues to the beginning of June. In the month of Auguſt, the weſt wind begins, and continues for three or four months. In the interval between theſe trade-winds, which is between the end of June and the be⯑ginning of Auguſt, the ſea is infeſted with vi⯑olent tempeſts from the north.'
'Theſe winds are ſubject to the greateſt va⯑riations near the coaſts: Veſſels cannot take their departure from the coaſt of Malabar, and other ports on the weſt coaſt of the peninſula of India, to Africa, Arabia, or Perſia, but from [382] the month of January to April or May; for, at the end of May, and during the months of June, July, and Auguſt, the tempeſts from the north and north-eaſt are ſo violent, that no ſhips can keep the ſeas. But, on the o⯑ther ſide of this peninſula, in the ſea which waſhes the coaſt of Coromandel, there are no tempeſts of this kind.'
'Veſſels depart from Java, Ceylon, and ſe⯑veral other places, for the Molucca's in Sep⯑tember, becauſe the weſt wind begins then to blow in theſe regions. However, when 15 degrees ſouth of the Equator, this wind ceaſes, and they fall in with the trade-wind, which, in this place, blows from the ſouth-eaſt. In the ſame manner, veſſels depart from Cochin for Malacca in March; becauſe, at this time, the weſt wind begins to blow. Thus the weſt winds ariſe at different times, in different parts of the Indian Ocean. The times of departure are different from Java to the Molucca's, from Cochin to Malacca, from Malacca to China, and from China to Japan.'
'At Banda, the weſt winds terminate at the end of March; calm and variable winds occu⯑py the month of April; and the eaſt winds begin with great violence in May. At Cey⯑lon, the weſt winds commence about the mid⯑dle of March, and continue to the beginning of October, when the eaſt, or rather eaſt-north-eaſt winds return. At Madagaſcar, they have [383] north or morth-weſt winds from the middle of April to the end of May; but eaſt and ſouth winds in February and March. From Madagaſcar to the Cape of Good Hope, the northerly winds prevail during the months of March and April. In the gulf of Bengal, af⯑ter the 20th of April, the ſouth winds blow with violence; and, before this period, the ſouth-weſt and north-weſt winds prevail. The weſterly winds are alſo violent in the Chineſe ſea during the months of June and July. This is, therefore, the moſt proper ſeaſon for ſail⯑ing from China to Japan: But, in returning from Japan to China, February and March are preferable, becauſe the eaſterly winds then prevail.'
'There are ſome winds which may be con⯑ſidered as peculiar to certain coaſts: For ex⯑ample, a ſouth wind blows almoſt perpetually on the coaſts of Chili and Peru. It begins a⯑bout the 46th degree of ſouth latitude, and ex⯑tends beyond Panama, which makes the voy⯑age from Lima to Panama more eaſy and ex⯑peditious than the return. The weſterly winds blow almoſt continually on the coaſts of Ma⯑gellan's land, in the neighbourhood of the ſtraits of Le Maire. Upon the Malabar coaſt, they have almoſt conſtantly north and north⯑weſt winds. The north wind is very frequent on the coaſt of Guinea. The weſterly winds [384] reign upon the coaſts of Japan during the months of November and December.'
The periodic, or alternate winds, mentioned above, are peculiar to the ſea. But, upon land, there are alſo periodic winds, which return at certain ſeaſons, or particular days, or even at ſtated hours. On the coaſt of Malabar, for ex⯑ample, an eaſterly land-wind blows from Sep⯑tember to April: It generally commences at midnight, and ends at noon; and it is not percep⯑tible at 12 or 15 leagues from the coaſt. From noon to midnight, there is a gentle weſterly breeze from the ſea. Upon the coaſts of New Spain in America, and upon thoſe of Congo in Africa, land-winds blow during the night, and ſea-winds during the day. Winds blow from all the coaſts of Jamaica during the night, which prevents the landing, or ſailing of ſhips, with ſafety, before the riſing of the ſun.
In winter, the port of Cochin is inacceſſible; neither can any veſſel get out; becauſe the winds are ſo impetuous, that no veſſels can keep the ſea; and, beſides, the weſt wind, which blows with great fury, drives ſuch a quantity of ſand into the mouth of the river, as renders it impoſ⯑ſible for ſhips of any burden to enter it for ſix months of the year. But the eaſt wind, which blows during the other ſix months, drives back the ſand into the ſea, and opens the mouth of the river. At the ſtraits of Babelmandel, there blows a ſouth-eaſt wind, which is regularly ſuc⯑ceeded [385] by the north-eaſt. At Saint Domingo, there are two different winds which riſe regu⯑larly every day; the one, which is from the ſea, comes from the eaſt, and begins at 10 o'clock before noon; the other, which is a land-wind from the weſt, riſes at 6 or 7 in the evening, and continues the whole night. Other facts of this kind, collected from voyagers of knowledge and credit, might furniſh a compleat hiſtory of the winds, which would be a work extremely uſeful both to navigation and phyſics.
THE winds are more irregular on the land than on the ſea, and in high than in low countries. The mountains not only change the direction of the winds, but even produce ſome, which are either conſtant or variable, according to their cauſes. The melting of ſnows on the tops of the mountains generally give riſe to conſtant winds which laſt a conſiderable time. The vapours which ſtrike againſt the mountains, and accumulate upon them, produce variable winds, which are very common in all climates; and there is as great a variety in the motions of [387] the air, as there are inequalities on the ſurface of the earth. We can only, therefore, give ex⯑amples and genuine hiſtory of facts: And, as a connected ſeries of obſervations upon the va⯑riations of the winds, and even of the ſeaſons, in different countries, is ſtill wanting, we ſhall not attempt to explain all the cauſes of theſe va⯑riations, but ſhall confine ourſelves to thoſe which are moſt probable.
In ſtraits, at the extremities of promontories, peninſula's, and capes, and in all narrow bays, tempeſtuous winds are frequent. But, indepen⯑dent of theſe, ſome ſeas are much more infeſted with ſtorms than others. The Indian Ocean the ſeas of Japan and of Magellan, along the Afri⯑can coaſt beyond the Canaries, and the oppoſite coaſt near Natal, and the Red and Vermilion Seas, are all ſubject to tempeſts. The Atlantic is likewiſe more tempeſtuous than the great o⯑cean called the Pacific: This ocean, however, is no where perfectly tranquil, but between the Tropics; for the nearer we approach the poles, it is the more ſubject to variable winds, the ſud⯑den changes of which produce tempeſts.
All continents are ſubject to the effects of va⯑riable winds, which are ſometimes very ſingu⯑lar. In the kingdom of Caſſimir, which is ſur⯑rounded with the mountains of Caucaſus, a moſt ſudden reverſe of ſeaſons is felt on Mount Pire⯑penjale. In leſs than an hour's journey, we paſs from ſummer to winter: A north and a ſouth [388] wind, according to Bernier, blow perceptibly within 200 paces of each other. The poſition of this mountain muſt be ſingular; and, there⯑fore, it merits a particular examination. In the peninſula of India, which is traverſed from north to ſouth by the mountains of Gate, the extreme heats of ſummer are felt on one ſide of thoſe moun⯑tains, and all the rigours of winter on the other. The ſame phaenomenon takes place on the two oppoſite coaſts of Cape Roſalgate in Arabia: On the north coaſt the ſea is calm and tranquil; while the ſouth coaſt is infeſted with continual ſtorms. Geylon exhibits another example of this phaenomenon; winter and high winds reign in the north part of the iſland, while, on the ſouth ſide of it, fine weather and ſummer heats prevail. Of oppoſite ſeaſons in the neigh⯑bourhood of each other, and at the ſame time, there are ſeveral examples, not only on the con⯑tinent, but on the iſlands, as at Cerem, a long iſland near Amboyna, in the north part of which it is winter, and ſummer in the ſouth part; and the interval between theſe two ſeaſons is not a⯑bove three or four leagues.
In Egypt a ſouth wind prevails in ſummer, which is ſo hot as to ſtop reſpiration; and it raiſes ſuch immenſe quantities of ſand, that the ſky ſeems to be covered with thick clouds. This ſand is ſo fine, and is blown with ſuch violence, that it penetrates the cloſeſt cheſts. When theſe winds continue for ſeveral days, they give riſe [389] to epidemic diſeaſes, which frequently cut off vaſt numbers of men. It ſeldom rains in Egypt; every year, however, there are ſome days of rain in the months of December, January, and Fe⯑bruary. But thick fogs are more frequent than rain, eſpecially in the neighbourhood of Cairo. Theſe fogs commence in November, and con⯑tinue during the winter; and, through the whole year, even when the ſky is ſerene, the dews fall ſo copiouſly, that they have all the effects of rain.
In Perſia, the winter commences in Novem⯑ber, and laſts till March. The cold is ſtrong e⯑nough to produce ice; and ſnows fall in the mountains, and ſometimes in the plains. From March to May, they have violent winds, which recal the warmth of ſummer. From May to September the ſky is ſerene, and the heats are moderated during the night by freſh breezes which continue till morning; and, in autumn, they have violent winds, like thoſe which blow in the ſpring. However, though theſe winds are very ſtrong, they ſeldom produce tempeſts or hurricanes. But, in ſummer, a very noxious wind blows along the Perſic Gulf, which is call⯑ed Samiel by the natives; it is ſtill hotter and more terrible than that of Egypt; and acting like an exploſion of inflamed vapour, it ſuſſo⯑cates every perſon who unhappily falls within its vortex. A ſimilar wind riſes in ſummer a⯑long the Red Sea, which ſuſſocates animals, and [390] tranſports ſuch quantities of ſand, that many people imagine this ſea will, in the courſe of time, be compleatly filled up with it. Ara⯑bia gives birth to frequent clouds of ſand which darken the air, and excite dangerous whirlwinds. At Vera Cruz, when the hot winds blow from the north, the houſes of that town are almoſt buried with ſand. Hot winds are alſo felt in ſummer at Negapatan in India, and likewiſe at Petapouli and Maſulapatan. Theſe ſcorching winds which kill men, are fortunately of no long duration; but they are extremely violent, and their heat and deleterious quality are propor⯑tioned to their velocity; which is contrary to the nature of other winds; for the more their rapidity, they are the more wholeſome and re⯑freſhing. This difference proceeds from the de⯑gree of heat in the air. When the heat of the air is leſs than that of the body, the motion of the air is agreeable. But, when the heat of the air is greater than that of the bodies of animals, its motion ſcorches and ſuſſocates. At Goa, the winter, or rather the rainy and tempeſtuous ſea⯑ſon, is in the months of May, June, and July; it cools and refreſhes the air, which would o⯑therwiſe be perfectly inſupportable in that re⯑gion.
The Cape of Good Hope is famous for its tempeſts, and a peculiar cloud which produces them. This cloud at firſt appears like a ſmall round ſpot in the heavens, which mariners di⯑ſtinguiſh [391] by the name of the Ox's Eye. The ſeeming ſmallneſs of this cloud is probably ow⯑ing to its great height. Of all voyagers who mention this cloud, Kolbe appears to have ex⯑amined it with the greateſt attention. 'This cloud,' ſays he*, 'which appears on the moun⯑tains of the Table, or of the Devil, or of the Wind, is compoſed, if I am not deceived, of an infinite number of particles puſhed, in the firſt place, againſt the mountains to the eaſt of the Cape, by the eaſt wind which blows in the Torrid Zone during almoſt the whole year. Theſe particles or vapours are ſtopped by the high mountains, and are collected on their eaſt ſide. They then become viſible in the form of ſmall fragments of clouds, which, by the conſtant action of the eaſt wind, are ele⯑vated to the tops of the mountains. Here they remain not long at reſt; but, being for⯑ced to advance, they ſink down between the mountains that are ſtill before them, where they are locked up and ſqueezed on all ſides as in a canal. The wind preſſes theſe vapours from above, and the oppoſite ſides of the two mountains confine them on the right and left, till, in their progreſs, they advance to the foot of ſome mountain where the country is more flat and open; they then expand, and become again inviſible. But they are ſoon puſhed againſt another ridge of mountains by freſh [392] clouds coming up behind them; and in this manner they proceed till they arrive with vaſt impetuoſity at the top of the higheſt moun⯑tains of the Cape, which are thoſe of the Wind or of the Table, where they are met by a wind blowing in the very oppoſite direction. Here a dreadful conflict enſues. The vapours are preſſed both before and behind, which pro⯑duces terrible whirlwinds, either on the moun⯑tains of the Table, or in the vallies. When the north-weſt wind yields, that of the ſouth-eaſt increaſes, and continues to blow with more or leſs violence for ſix months. When the Ox's Eye is thick, the force of the ſouth-eaſt wind augments, becauſe the vapours amaſſed behind the mountains continually preſs forward; for the ſame reaſon, this wind diminiſhes when the Ox's Eye is thin; and it entirely ceaſes when the Ox's Eye vaniſhes, becauſe no va⯑pours arrive from the eaſt.'
'The circumſtances attending this phaeno⯑menon lead to the following hypotheſis: 1. Behind the mountain of the Table, a train of thin white vapour is obſerved, which com⯑mences on the eaſtern declivity of this moun⯑tain, ends in a ſharp point at the ſea, and occu⯑pies, in its extent, the whole mountains of Stone. I have often contemplated this train, and imagined it to originate from the rapid motion of the vapour above deſcribed, from the mountains of Stone to that of the Table.'
[393] '2. The paſſage of theſe vapours muſt be ex⯑tremely embarraſſed by the contrary ſhocks received, not only from the mountains, but from the ſouth and eaſt winds which prevail in the neighbourhood of the Cape. I have al⯑ready mentioned the two mountains ſituated on the points of Falſe bay, the one called the Hanging Lip, the other the Norvege. When the particles or vapours, which I have conjec⯑tured, are puſhed againſt thoſe mountains by the eaſt winds, they are repelled by the ſouth winds, and driven againſt the neighbouring mountains, where they are detained for ſome time, and appear like clouds, as they often do upon the mountains of Falſe bay, and even be⯑yond them. Theſe clouds are frequently very thick above the land in the poſſeſſion of the Dutch, upon the mountains of Stellenboſck, of Draken⯑ſtein, and of Stone, but eſpecially upon the mountains of the Table and of the Devil.'
'Laſtly, The conſtant appearance of ſmall black clouds upon the Lion's Head two or three days before the ſouth-eaſt winds blow, con⯑firms me in my conjecture; for theſe clouds, in my opinion, are compoſed of the particles or vapour mentioned above. If the north-weſt wind prevails when theſe particles arrive, their courſe is ſtopped; but they are never driven to any great diſtance till the ſouth-eaſt wind commences.'
[394] The navigators who firſt approached the Cape of Good Hope, were ignorant of the effects of theſe clouds, which ſeemed to ariſe ſlowly and without any agitation in the air, but which, in a moment, excite the moſt furious tempeſts, and precipitate the largeſt veſſels to the bottom of the ocean. In the country of Natal, a cloud ſi⯑milar to the Ox's Eye at the Cape, produces the ſame direful effects. Theſe ſpecies of tempeſts are frequent in the Atlantic, eſpecially in the neighbourhood of the Equator. Near the coaſt of Guiney, three or four of theſe ſtorms ſome⯑times happen in a day, which are likewiſe occa⯑ſioned and announced by ſmall black clouds, while the reſt of the ſky is generally ſerene, and the ſea perfectly calm. It is principally in April, May, and June, that theſe furious ſtorms ariſe along the coaſt of Guiney, becauſe no re⯑gular winds blow there at that ſeaſon. On the coaſt of Loango, the ſtormy ſeaſon is in the months of January, February, March, and April. At Cape Gardafu, on the other ſide of Africa, they have ſtorms of this kind in May, and the clouds which produce them are generally in the north, like thoſe of the Cape of Good Hope.
All theſe ſtorms originate from winds that iſ⯑ſue from a cloud; and their direction is from north to ſouth, or from north-eaſt to ſouth-weſt, &c. But there are tempeſts of another kind, called Whirlwinds, which are ſtill more violent, and in which the wind ſeems to blow from e⯑very [395] quarter at once. Their motion is circular, and nothing can reſiſt their fury. They are ge⯑nerally preceded by a dead calm; but, in an inſtant, the waves are elevated to the clouds by the fury of the winds. Some parts of the ſea cannot be approached; becauſe they are perpe⯑tually infeſted either with calms or whirlwinds. Theſe places have been called calms and torna⯑dos by the Spaniards. The moſt conſiderable of them are near Guiney, about the 2d or 3d degree of north latitude. They extend about 300 or 350 leagues in length, and nearly as much in breadth, which includes a ſpace of more than 100,000 ſquare leagues.
When contrary winds arrive at the ſame time in the ſame place, they produce whirlwinds, by the oppoſite motion of the air, in the ſame manner as whirlpools are produced in the ſea by contrary currents. But, when thoſe oppo⯑ſite winds are counterbalanced by their diſtant action upon each other, they then revolve in a great circle, and produce a perfect calm, which it is impoſſible for veſſels to paſs through. Theſe places are all marked in the globes of Mr Se⯑nex. I am inclined to think, that the contrariety of the winds alone, if not aſſiſted by the direc⯑tion of the coaſts, and the particular ſtructure of the bottom of the ſea in theſe places, could not produce this effect. I imagine that the cur⯑rents, which are in effect occaſioned by the winds, but aſſume their direction from the fi⯑gure [396] of the coaſts and the inequalities at the bottom, terminate in theſe places; and that their oppoſite motions, in a plain ſurrounded with a chain of mountains, give riſe to the tornados in queſtion.
Whirlpools ſeem to be nothing elſe but cir⯑cular motions of the waters occaſioned by the action of two or more oppoſite currents. The Euripus, ſo famed by the death of Ariſtotle, al⯑ternately abſorbs and rejects the water ſeven times every 24 hours. This whirlpool is near the coaſt of Greece. Charybdis, which lies near the ſtraits of Sicily, rejects and abſorbs the wa⯑ter thrice in 24 hours. We are uncertain as to the number of alternate motions in other whirl⯑pools. Dr Placentia informs us, that the mo⯑tions of the Euripus are irregular for 18 or 19 days every month, and regular during the other 11; and that it ſeldom ſwells above one, or at moſt two feet. He farther informs us, that au⯑thors are not agreed as to the tides in the Eu⯑ripus; that ſome ſay it is twice, others ſeven times, ſome eleven, others 12 or 14 times in 24 hours; but that Loirius, who examined it attentively, found that the tides roſe regularly e⯑very ſix hours, and that their motion was ſuffi⯑cient to turn a mill-wheel.
The largeſt known whirlpool is in the ſea of Norway, the circumference of which exceeds 20 leagues. It abſorbs, for ſix hours, water, whales, ſhips, and any thing that approaches it, [397] and the next ſix hours are employed in throwing them up again.
To account for theſe whirlpools, it is unne⯑ceſſary to have recourſe to an abyſs, or to pits in the bottom of the ſea, which are perpetually ſwallowing the waters. It is well known, that, when water has two directions, the combination of theſe motions produces a whirling, and exhi⯑bits the appearance of a void ſpace in the middle. In the ſame manner, whirlpools in the ſea are occaſioned by two or more contrary currents; and, as the tides are the principal cauſe of cur⯑rents, and, of courſe, they run for ſix hours in contrary directions, it is not ſurpriſing, that the whirlpools which are produced by them ſhould alternately reject and abſorb every thing within their reach during the ſame portions of time.
Whirlpools, then, are occaſioned by contrary currents, and whirlwinds by the conflict of contrary winds. Theſe whirlwinds are com⯑mon in the Chineſe and Japaneſe ſeas, near the Antilles, and in many other places of the ocean, particularly in the neighbourhood of prominent coaſts. But they are ſtill more frequent upon land; and their effects are ſometimes prodigious. 'I have ſeen,' ſays Bellarmin*, 'an enormous ditch ſcooped out by the wind, tranſported in the air, and dropped upon a village, which was for ever buried under this load of earth.' A detail of the effects of ſeveral hurricanes may be [398] ſeen in the hiſtory of the French Academy, and in the Philoſophical Tranſactions, which would appear altogether inconceivable, if they were not atteſted by intelligent and credible ſpectators.
The ſame obſervation may be made with re⯑gard to water-ſpouts, which the mariner never beholds without terror and amazement. They are very common on certain coaſts of the Medi⯑terranean, eſpecially when the weather is cloudy, and the wind blows from ſeveral coaſts at the ſame time. They are more frequent near the coaſts of Laodicea, of Grecgo, and of Carmel, than in any other part of the Mediterranean. Moſt of them are large cylinders of water which fall from the clouds, though, at a diſtance, the water appears to riſe up from the ſea to the clouds*.
But there are two ſpecies of water-ſpouts; the firſt is that we have juſt mentioned, and is nothing but a thick cloud compreſſed, and ſur⯑rounded by oppoſite winds blowing from dif⯑ferent coaſts at the ſame time, which make it aſſume a cylindric figure, and fall down by its own gravity. The quantity of water is ſo im⯑menſe, and the rapidity of the fall ſo great, that if, unfortunately, one of theſe ſpouts break up⯑on a ſhip, it daſhes it to pieces, and ſinks it in an inſtant. It is alledged, and with probability, that water-ſpouts may be broken and diſſipated by the commotion excited in the air by the [399] firing of cannons, which correſponds with the diſſipation of thunder-clouds by the ringing of bells.
The other ſpecies of water-ſpout is called a typhon, and is very frequent in the Chineſe Sea. The typhon deſcends not from the clouds, nor is produced by the action of oppoſite winds. It, on the contrary, riſes from the water to the heavens with amazing rapidity. Whirlwinds often run along conſiderable tracts, bearing down houſes, trees, and every obſtacle that they meet with. But typhons remain always in the ſame places, and can be owing to nothing but ſubterraneous fires; for the ſea is then in the greateſt agitation, and the air is ſo impregnated with ſulphureous exhalations, that the ſky ap⯑pears to be covered with a copper-coloured cruſt, although there be no clouds, and the ſun or the ſtars appear through the vapour. It is to theſe ſubterranean fires that we muſt aſcribe the warmth of the Chineſe Sea in winter, where theſe ty⯑phons are very frequent*.
Thevenote, in his voyage to the eaſt, gives the following account of water-ſpouts: 'We ſaw water-ſpouts in the Perſic gulf, between the iſlands of Queſomo, Lareca, and Ormutz. Few have had the opportunity, and fewer ſtill have paid the attention to water-ſpouts, that I have done. I ſhall deſcribe them with perſpicuity [400] and ſimplicity, in order to render my account the more eaſily intelligible.'
'The firſt that we ſaw, was on the north ſide between us and the iſland of Queſomo, about a gun-ſhot from our ſhip. In this place, we ſaw the water begin to boil, and to be raiſed about a foot above the ſurface: It was whitiſh, and the top of it appeared like black ſmoke: It made a kind of whiſpering noiſe, like a tor⯑rent ruſhing down with violence into a deep valley. This noiſe was mingled with another that reſembled the hiſſing of ſerpents. A little afterwards, we ſaw an obſcure canal or pipe, which reſembled ſmoke riſing to the clouds, and revolved with conſiderable velocity: This pipe was about the ſize of a man's finger; and the ſame noiſe continued. It then vaniſhed, having continued in all about a quarter of an hour. We then perceived another on the ſouth, which began in the ſame manner as the former: Immediately a third ſprung up to the weſt, and then a fourth likewiſe to the weſt; the moſt diſtant not exceeding a muſket-ſhot from us. Each of them appeared like heaps of ſmoking ſtraw, and were accompanied with the ſame noiſe as the firſt. We next per⯑ceived three pipes, or canals, extending from the water to the clouds, where each of them terminated like the mouth of a funnel or trumpet, or like the paps of an animal drawn perpendicularly downward by a weight. Theſe [401] pipes were of a dark white colour, which I imagined to be owing to the water they con⯑tained; for the pipes appeared to be formed before they were filled with the water, and they diſappeared when they were empty; in the ſame manner as a cylinder of clear glaſs, when held up in the light at a diſtance from the eye, is not viſible, unleſs it be filled with ſome coloured liquor. Theſe pipes were not ſtraight, but bent in ſome places: They were not even perpendicular; on the contrary, from the clouds into which they were ingrafted, to the places from which they extracted the wa⯑ter, they were very much inclined. And, what is ſingular, the cloud to which the ſecond of the three was attached, having been puſhed forward by the wind, the pipe followed it without breaking, or quitting its ſtation in the water; and, paſſing behind the pipe of the firſt, they remained for ſome time in the form of a St Andrew's croſs. At firſt, none of the three exceeded an inch in thickneſs, excepting where they joined the cloud: But the one that ap⯑peared firſt, ſwelled afterwards conſiderably. The other two continued not longer than the one we had ſeen to the north. The ſecond, on the ſouth, laſted about a quarter of an hour; but the firſt, on the ſame ſide of the veſſel, continued longer, and gave us ſome un⯑eaſineſs; of it, therefore, we have ſtill farther to remark, that, although it originally was not [402] larger than a man's finger, it gradually ſwelled to the ſize of an arm, then to that of a leg, and, laſtly, to that of the trunk of a tree as large as a man could encompaſs with both his arms. We ſaw the water riſing diſtinctly through this tranſparent body, which was of a ſerpen⯑tine form; and it ſometimes diminiſhed in thickneſs both above and below. It now ex⯑actly reſembled a ſoft tube filled with water, and preſſed with the fingers, either above to make the fluid deſcend, or below to make it aſcend; and I was ſatisfied that theſe variations were occaſioned by the wind, which, when it preſ⯑ſed the canal above, cauſed the water to de⯑ſcend, and when the preſſure was lower down, made the water aſcend. After this, it dimi⯑niſhed to the ſize of a man's arm; then it ſwel⯑led to the ſize of a thigh; then became ex⯑ceedingly ſmall; laſtly, I perceived that the water elevated from the ſurface began to ſink, and the end of the canal ſeparated from it; when a variation of the light removed it from my view. I ſtill, however, continued to look for it, becauſe I had remarked, that the canal of the ſecond ſpout appeared to break in the middle, and to reunite a little afterwards, one half of it having been concealed by the light; but this laſt never more appeared.'
'Theſe ſpouts are exceedingly dangerous at ſea; for, when they fall upon a veſſel, they mingle ſo with the ſails, that they ſometimes [403] raiſe the veſſel up, and let it fall back again with ſuch violence as to ſink it. But, although they ſhould not raiſe the ſhip, they tear the ſails, or let the whole water they contain fall upon the veſſel, which precipitates it to the bottom. It is not improbable, that many veſ⯑ſels, of which we never have any accounts, periſh by ſuch accidents; for there are few examples of our ever learning with certainty of ſhips being loſt in this manner.'
In the above account of water-ſpouts, there appears to be ſeveral optical illuſions. But I have related the facts verbatim, that they may either be confirmed, or at leaſt compared with thoſe of other navigators. M. Gentil, in his voyage round the world, deſcribes water-ſpouts in the following manner: 'At eleven o'clock, before noon, the ſky being cloudy, we ſaw round our ſhip, at the diſtance of about a quar⯑ter of a league, ſix water-ſpouts, which began with a noiſe like that of water running below ground, and gradually increaſed till it reſembled the hiſſing noiſe occaſioned by a high wind a⯑mong the ropes of a ſhip. We firſt perceived that the ſea began to boil; and its ſurface roſe about a foot and a half; the top of this ele⯑vated part was covered with a thick fog, or rather ſmoke, which formed itſelf into a canal, and mounted to the clouds. Theſe canals bended according as the wind carried the clouds to which they were attached. Not⯑withſtanding [404] the motion communicated to the clouds by the wind, the canals not only ad⯑hered to them, but ſeemed to ſtretch out, or contract, in proportion as the clouds roſe high⯑er, or ſunk down in the atmoſphere.'
'Theſe appearances gave us much uneaſineſs; and our ſailors, inſtead of encouraging each o⯑ther, increaſed their fears by dreadful ſtories. If theſe ſpouts, ſaid they, fall upon the ſhip, they will lift her up, and then plunge her to the bottom. Others maintained, with a deci⯑ſive tone, that they would not lift the veſſel; but that, being full of water, if the ſhip went forward, ſhe would break their communication with the ſea, and that the great body of water, by falling perpendicularly on the veſſel, would break her in pieces.'
'To prevent this misfortune, they lowered the ſails, and charged the cannon. It is a ge⯑neral opinion among ſailors, that the firing of cannon, by agitating the air, burſts and diſper⯑ſes water-ſpouts. But we were not under the neceſſity of having recourſe to this expedient; for, after courſing round the ſhip for about ten minutes, ſome being about a quarter of a league from us, and others nearer, the canals became gradually narrower, detached them⯑ſelves from the ſurface of the ſea, and then entirely vaniſhed*.'
[405] From the deſcription of theſe two voyagers, it appears, that water-ſpouts are produced, at leaſt in part, by the action of fire or ſmoke, which riſes with violence from the bottom of ſea; and that they are very different from thoſe which are occaſioned by oppoſite winds: 'The water-ſpouts,' ſays Mr Shaw*, 'which I had the opportunity of ſeeing, ſeemed to be ſo ma⯑ny cylinders of water falling down from the clouds; though, by the reflection, it may be of thoſe deſcending columns, or from the ac⯑tual dropping of the water contained in them, they would ſometimes appear, eſpecially at a diſtance, to be ſucked up from the ſea. Nothing more, perhaps, is required to explain this phae⯑nomenon, than that the clouds ſhould be firſt of all crouded together, and then, that contrary winds, preſſing violently upon them, ſhould occaſion them to condenſe, and fall in this cy⯑lindrical manner.'
Many facts remain ſtill to be known before theſe phaenomena can be properly explained. To me it appears, that, if there be, in particular places, at the bottom of the ſea, a mixture of ſulphur, bitumen, and mineral ſubſtances, theſe may oc⯑caſionly be inflamed, which will produce, like the exploſion of gun-powder, a great quantity of air; and that this air newly generated, and rarefied to a prodigious degree, mounts with ra⯑pidity, and may elevate the water from the ſea [406] to the clouds. In the ſame manner, if a perpen⯑dicular current of air be produced by the explo⯑ſion of ſulphureous matter in a cloud, the whole of its water may follow this current, and give riſe to a water-ſpout from the clouds to the ſea. But, it muſt be acknowledged, that this account of the laſt ſpecies of ſpout is not more ſatisfac⯑tory than that which we have given of thoſe produced by contrary winds; for, it may be aſk⯑ed, why thoſe ſpouts which originate from the clouds, are not as common on land as upon the ſea?
The hiſtorian of the academy for the year 1727, mentions a land water-ſpout which ap⯑peared at Capeſtan near Beziers. It deſcended from a cloud like a black pillar, which gradually diminiſhed, and ended in a point upon the ſur⯑face of the earth. It followed the direction of the wind, which was weſterly; it was attended with a thick ſmoke, and made a noiſe like the ſea when greatly agitated. It tore up trees by the roots, and marked its way on the earth by a large tract in which three carriages might have paſſed each other. Another pillar of the ſame kind appeared, but it ſoon joined the firſt; and, when the whole was diſſipated, there fell a great quantity of hail.
This ſpecies of water-ſpouts appears to be dif⯑ferent from the other two. It is not ſaid to have contained water; and it ſeems, both from what I have mentioned, and by M. Andoque's expli⯑cation [407] of it to the academy, to have been only a hurricane rendered viſible by the duſt and con⯑denſed vapour which it contained. The ſame hiſtorian, for the year 1741, mentions a water-ſpout which was ſeen upon the lake of Geneva. It was of a cylindrical figure, the upper part of which ended in a black cloud, and the under part of it was narrow, and terminated near the ſurface of the water. This meteor continued only a few minutes; and, at the moment of its diſſipation, a thick vapour aſcended from the place where it firſt appeared; the water of the lake boiled, and ſeemed to make an effort to riſe in⯑to the air, which was very calm the whole time; neither was this ſpout followed either by wind or rain. 'After all our knowledge of water-ſpouts,' ſays the hiſtorian, 'does not this prove that they are not produced by the conflict of oppoſite winds alone, but that they almoſt al⯑ways originate from volcano's or ſubterrane⯑ous vapours, which are known to exiſt at the bottom of the ſea, as well as upon land? Whirl⯑winds and hurricanes, therefore, which are ge⯑nerally believed to be the cauſe of theſe appear⯑ances, may be only an effect or an accidental conſequence of them.'
THE bowels of thoſe burning mountains called volcano's, contain ſulphur, bitumen, and other inflammable materials, the effects of which are more violent than thoſe of thunder or of gun-powder; and they have, in all ages, aſtoniſhed mankind, and deſolated the earth. A volcano is an immenſe cannon, with an aperture often more than half a league in circumference. From this vaſt mouth are projected torrents of ſmoke and of flames, rivers of bitumen, of ſul⯑phur, and of melted metals, clouds of aſhes and ſtones; and ſometimes it ejects, to the diſtance of ſeveral leagues, rocks ſo enormous, that they could not be moved by any combination of hu⯑man [409] man powers. The conflagration is ſo dreadful, and the quantities of burning, calcined, melted, and vitrified ſubſtances thrown out by the moun⯑tain are ſo great, that they bury whole towns and foreſts, cover the plains to the thickneſs of a hundred or two hundred feet, and ſome⯑times from hills and mountains, which are only portions of theſe matters heaped up and com⯑pacted into one maſs. The action of the fire and the force of the exploſions are ſo violent, that they produce, by reaction, ſuccuſſions, which ſhake the earth, agitate the ſea, overturn moun⯑tains, and deſtroy towns and buildings of the moſt ſolid materials.
Theſe effects, though natural, have been re⯑garded as prodigies; and, though we often be⯑hold, in miniature, effects ſimilar to thoſe of vol⯑cano's; yet grandeur, from whatever ſource it proceeds, has ſuch an aſtoniſhing influence up⯑on the imagination, that it is not ſurpriſing they ſhould have been conſidered by ſome authors as vents to a central fire, and, by the vulgar, as mouths of hell. Aſtoniſhment produces fear, and fear is the ſource of ſuperſtition. The in⯑habitants of Iceland firmly believe that the groan⯑ings of their volcano are the cries of the damned, and that its eruptions are occaſioned by the de⯑ſperation and ungovernable fury of devils and tormented ſpirits.
All theſe phaenomena, however, are only the effects of fire and of ſmoke. In the bowels of [410] mountains, there are veins of ſulphur, bitumen, and other inflammable ſubſtances, together with vaſt quantities of pyrites, which ferment when expoſed to the air, or to moiſture, and produce exploſions proportioned to the quantity of in⯑flammable matter. This is the true idea of a volcano; and it is eaſy for the naturaliſt to imi⯑tate the operation of theſe ſubterraneous fires. A mixture of ſulphur, of filings of iron, and of water, buried at a certain depth below the ground, will exhibit, in miniature, all the ap⯑pearances of a volcano: This mixture ſoon fer⯑ments to a degree of inflammation, throws off the earth and ſtones which cover it, and produces exploſions every way ſimilar to thoſe of burn⯑ing mountains.
The moſt famous volcano's in Europe are thoſe of Mount Aetna in Sicily, of Mount Hecla in Iceland, and of Mount Veſuvius, near Naples in Italy. The burning of Mount Aetna is more antient than the records of hiſtory. Its erup⯑tions are extremely violent; and the quantity of matter it throws out is ſo enormous, that, af⯑ter digging 68 feet deep, marble pavements, and other veſtiges of an antient city, have been found covered with this amazing load of earth, in the ſame manner as the town of Herculane⯑um has been buried with the matter ejected from Mount Veſuvius. New mouths, or cra⯑ters, were opened in Aetna, in the years 1650, 1669, and at other times. The ſmoke and [411] flames of this volcano are ſeen as far as Malta, a diſtance of 60 leagues: It ſends forth a perpe⯑tual ſmoke, and, at particular times, it throws out, with an aſtoniſhing violence, flames, lava, huge ſtones, and matter of every kind. An e⯑ruption of this volcano, in the year 1537, pro⯑duced an earthquake over the whole iſland of Sicily, which laſted 12 days, and overthrew an immenſe number of houſes and public buildings. It terminated by the burſting of a new mouth, the lava of which burnt up every thing within five leagues of the mountain. It diſcharged aſhes ſo abundantly, and with ſuch force, that they reached the coaſt of Italy, and incommoded veſſels at great diſtances from the iſland. This volcano has, at preſent, two principal craters, one of which is narrower than the other. They both ſmoke perpetually; but flames only appear during the time of eruptions. Large ſtones, it is ſaid, have been projected from them to the di⯑ſtance of 60,000 paces.
A violent eruption, in 1683, produced a dreadful earthquake in Sicily. It laid the whole city of Catanea in ruins, and killed more than 60,000 of its inhabitants, beſide thoſe who periſhed in the neighbouring towns and villages.
Hecla darts its fires through the ſnows and ice of a frozen climate. Its eruption, how⯑ever, are equally violent with thoſe of Aetna, and other volcano's in the more ſouthern regions. It throws out aſhes, lava, pumice-ſtones, and [412] ſometimes boiling water. The whole iſland of Iceland abounds in ſulphur; but it is not habi⯑table within leſs than ſix leagues of the volcano. The hiſtory of its moſt violent eruptions is re⯑corded in a book written by Dithmar Bleffken.
According to hiſtorians, the burning of mount Veſuvius began not before the ſeventh conſulate of Titus Veſpaſian, and Flavius Domitian. The top of the mountain then opened, and at firſt threw out ſtones and rocks; theſe were ſuc⯑ceeded by flames and lava, which burned up two neighbouring cities, and volumes of ſmoke ſo thick as to darken the light of the ſun. The elder Pliny, ſtimulated by curioſity, approached too near the mountain, and was ſuffocated by its ſulphureous ſteams*. Dion Caſſius relates, that this eruption was ſo violent, that aſhes and ſulphureous ſteams were tranſmitted as far as Rome, and acroſs the Mediterranean into Africa and Egypt. Heraclea was one of the cities that were overwhelmed by the matter ejected from the mountain: It has lately been diſcovered 60 feet under the ſurface of the ground, which, in the courſe of time, had become arable, and fit for every kind of culture. The hiſtory of the diſcovery of Heraclea is in the hands of the pu⯑blic. We have only to wiſh, that ſome perſon, ſkilled in the knowledge of nature, would exa⯑mine with attention the different materials which compoſe this 60 feet of earth, and remark their [413] ſituation, the alterations they have undergone, the direction they have followed, the hardneſs they have acquired, &c.
Naples appears to be ſituated upon a vault filled with burning minerals; for Veſuvius and Solfatara ſeem to have ſubterraneous communi⯑cations. When Veſuvius throws out lava, Sol⯑fatara emits flames; and, when the eruptions of the former ceaſe, the burning of the latter is likewiſe extinguiſhed. The city of Naples is nearly in the centre between them.
One of the laſt, and moſt dreadful, eruptions of Veſuvius, happened in the year 1737*. The mountain diſcharged, from ſeveral mouths, im⯑menſe torrents of melted matter, which ſpread over the fields, and terminated in the ſea. M. de Montealegre, who communicated this account of it to the Academy of Sciences, obſerved, with horror, one of theſe rivers of fire, which, from its ſource to the ſea, was about 7 miles in length, 50 or 60 paces broad, from 25 to 30 palms deep, and in the vallies 120 palms. The running matter reſembled foam, or the droſs which iſſues from a furnace, &c.†
In Aſia, and particularly in the iſlands of the Indian ocean, volcano's are numerous. One of the moſt famous is Mount Albours, near Mount Taurus, about 8 leagues from Herat. The top [414] of this mountain ſends forth a pepetual ſmoke; and it frequently throws out flames and burning matter, in ſuch quantities as to cover all the ad⯑jacent plains with aſhes. In the iſland of Ter⯑nate, there is a volcano which diſcharges matter ſimilar to pumice-ſtones. Some voyagers al⯑ledge, that this volcano is moſt furious during the equinoxes, becauſe theſe periods are attended with certain winds which increaſe the inflam⯑mation of theſe fires, that have continued to burn for ages*. The iſland of Ternate is not above 7 leagues round, and is only the top of a large mountain. The land riſes from the coaſt to the middle of the iſland, where the volcano mounts to a height ſo great, that it is difficult to get to the top of it. Several rills of ſweet wa⯑ter deſcend from the ſides of the mountain; and, when the air is calm, and the weather fine, this burning gulf is leſs agitated than during ſtorms and high winds†. This confirms what I for⯑merly remarked, and ſeems to prove, that the fire of volcano's proceeds not from a great depth, but from the top, or higher parts of the mountain; for, if it were otherwiſe, high winds could not increaſe the violence of the flames. There are other volcano's in the Molucca iſlands. In one of the iſlands of Mauritius, about 70 leagues from the Moluccas, there is a volcano, the effects of which are equally violent as thoſe [415] of the mountain in Ternate. The iſland of Sorca, one of the Moluccas, was formerly inha⯑bited. In the middle of this iſland there is a very high mountain, with a volcano at the top of it. In 1693, this volcano diſcharged in im⯑menſe quantity of bitumen, and inflamed mat⯑ter, which, forming a burning lake, gradually extended till it covered the whole iſland*.
There are ſeveral volcano's in Japan, and the adjacent iſlands, which ſend out flames in the night, and ſmoke in the day. In the Philippine iſlands there are likewiſe ſeveral burning moun⯑tains. One of the moſt remarkable, and, at the ſame time, the moſt recent volcano in the Indian iſlands, is that near the town of Panarucan in the iſland of Java. It commenced in the year 1586; and, at the firſt eruption, it threw out immenſe quantities of ſulphur, bitumen, and ſtones. The ſame year, Mount Gounapi, in the iſland of Banda, which had been a volcano only about 17 years, opened and ejected, with a dreadful noiſe, rocks and matter of every kind. There are ſtill other volcano's in India, as in Sumatra, and in the north of Aſia, beyond the river Je⯑niſcea, and the river Peſida: But the two laſt are little known.
Near Fez in Africa, there is a mountain, or rather a cavern, called Beni-guazeval, which conſtantly throws out ſmoke, and ſometimes flame. One of the Cape de Verd iſlands, called [416] the iſland of Fuogo, is nothing but a huge mountain which burns inceſſantly. This vol⯑cano caſts out ſtones and aſhes; and the Portu⯑gueze, who often attempted to inhabit the iſland, have always abandoned the project, on account of the volcano. The Peak of Teneriff, which is reckoned one of the higheſt mountains in the world, throws out fire, aſhes, and large ſtones. From the top of it, rivulets of melted ſulphur run down the ſouth ſide acroſs the ſnows; this ſulphur ſoon condenſes and forms veins in the ſnow, which are diſtinguiſhable at great di⯑ſtances.
America, and particularly the mountains of Mexico and Peru, are much infeſted with vol⯑cano's: That of Arequipa is one of the moſt ce⯑lebrated: It often produces great earthquakes, which are more frequent in Peru than in any country of the world. Next to Arequipa, the volcano's of Carrapa and Malahallo are, accor⯑ding to the relation of travellers, the moſt con⯑ſiderable. But there are many others in the new world of which we have no knowledge. M. Bouguer, in his voyage to Peru, publiſhed in the Memoirs of the Academy for the year 1744, mentions two volcano's, the one called Cotopaxi, and the other Pichincha. The firſt is at ſome diſtance from, and the other very near, the town of Quito. In the year 1742, he ſaw an erup⯑tion of Cotopaxi, which, at that time, burſt open a new mouth in the mountain. It did no [417] other damage than that of melting the ſnow, and producing ſuch torrents, as, in three hours, laid the whole country, to the extent of 18 leagues, under water, and overturned every thing that came in their way.
Popochampeche and Popocatepec are the chief volcano's in Mexico. It was near this laſt that Cortes paſſed in his way to the city of Mexico: Some of the Spaniards aſcended to the top of the mountain, where they found the cra⯑ter to be about half a league in circumference. Sulphureous mountains have alſo been found in Guadaloupe, Tercera, and in others of the A⯑zore iſlands; and, if all the mountains from which ſmoke or flames iſſue were to be conſi⯑dered as volcano's, their number would exceed 60. We have only mentioned thoſe which are ſo formidable as, by their frequent eruptions, to prevent people from living near them.
The numerous volcano's in the Cordeliers, as I formerly remarked, produce almoſt perpe⯑tual earthquakes, which prevent the inhabitants from building with ſtone any higher than the firſt floor; and the upper part of their houſes, for the ſame reaſon, are conſtructed with ruſhes or very light wood. In theſe mountains there are alſo many precipices and large gulfs, the walls of which are black and burned: They are ſimilar to the precipice of Mount Ararat in Armenia, called the Abyſs, and are the craters of extinguiſh⯑ed volcano's.
[418] A late earthquake at Lima was attended with the moſt dreadful effects. The town of Lima, and the port of Callao, were almoſt entirely ſwallowed up. But the miſchief was ſtill more terrible at Callao. The ſea roſe and covered every houſe in that unfortunate town, and drown⯑ed the whole inhabitants, leaving only a ſingle tour as a monument of its devaſtations. Of 25 veſſels that lay in the harbour, four were driven a league upon land, and the reſt ſwallowed up by the waves. Of Lima, which was a very large city, only 27 houſes remained ſtanding. Mul⯑titudes of people periſhed; and the diſaſter was particularly fatal to the monks and other reli⯑gious, becauſe their buildings were lofty, and of more ſolid materials than the common houſes. This calamity happened in the month of Octo⯑ber 1746, during the night; and the ſuccuſſion laſted 15 minutes.
Near the port of Piſca, in Peru, there was formerly a famous city, ſituated on the ſea-coaſt; but, on the 19th of October 1682, it was almoſt entirely deſtroyed by an earthquake; for the ſea, having exceeded its uſual limits, ſweeped away this unfortunate city, with all its inhabitants.
By conſulting hiſtorians and travellers, we ſhall find many accounts of earthquakes, and e⯑ruptions of volcano's, equally dreadful and de⯑ſtructive as thoſe we have already mentioned. [419] Peſidonius, quoted by Strabo*, relates, that a city of Phoenicia, near Sidon, was ſwallowed up by an earthquake, with the neighbouring territory, and two thirds of Sidon itſelf; that this effect was not produced ſo ſuddenly as to prevent the inhabitants from eſcaping by flight; that it extended over moſt of Syria, and as far as the Cyclades iſlands and Euboea, where the fountains of Arethuſa ſuddenly ſtopped, and ap⯑peared a few days afterwards by new ſources at a conſiderable diſtance from the old ones; and that the earthquake continued to ſhake the iſland ſometimes in one place, and ſometimes in ano⯑ther, till the earth opened in the valley of Le⯑panta, and diſcharged a great quantity of burn⯑ing matter. Pliny informs us†, that, in the reign of Tiberius, twelve cities in Aſia were o⯑verturned; and he mentions‡, in the following terms, a prodigy occaſioned by a violent earth⯑quake. 'Factum eſt ſemel (quod equidem in Etruſcae diſciplinae voluminibus inveni) ingens terrarum portentum, Lucio Marco, Sex. Ju⯑lio Coſſ. in agro Mutinenſi. Namque mon⯑tes duo inter ſe concurrerunt, crepitu maxi⯑mo adſultantes recedenteſque, inter cos flam⯑ma, fumoque in coelum exeunte interdiu, ſpec⯑tante e via Aemilia magna equitum Romano⯑rum familiarumque et viatorum multitudine. Eo concurſu villae omnes eliſae, animalia per⯑multa, quae intra fuerant, exanimata ſunt,' [420] &c. St Auguſtin tells us*, that, in Lybia, 100 towns were deſtroyed by an earthquake. In the time of Trajan, the earth opened and de⯑voured the city of Antioch, and a great part of the adjacent country. It was again deſtroyed by the ſame cauſe during the reign of Juſtinian in the year 528, and 40,000 of its inhabitants periſhed. It was viſited with a third earthquake in the days of St Gregory, ſixty years after the former, which deſtroyed no leſs than 60,000 of its inhabitants. In the reign of Saladin, anno 1182, moſt of the cities of Syria and of Judea were laid waſte by the ſame calamity. Earth⯑quakes have been more frequent in Apulia and Calabria than in any other part of Europe. In the time of Pope Pius II. all the churches and palaces of Naples were thrown down, and about 30,000 lives were loſt: Thoſe who eſcaped were obliged to live in tents till houſes were built for them. In 1629, 7000 perſons periſhed in A⯑pulia by earthquakes; and, in 1638, the city of Saint Euphemia was ſwallowed up, and left behind it nothing but a ſtinking lake: At the ſame time, Raguſa and Smyrna were almoſt to⯑tally deſtroyed. In 1692, an earthquake was felt in Britain, Holland, Flanders, Germany, and France: It was moſt ſevere along the coaſts of the ſea, and near great rivers. It agitated at leaſt 2600 ſquare leagues, though it laſted but two minutes. The commotion was greater in [421] the mountains than in the vallies*. On the 10th of July 1688, there was an earthquake at Smyrna, which began with a motion from weſt to eaſt. The caſtle was firſt overturned; its four walls ſeparated from each other, and ſunk ſix feet in the ſea. This caſtle ſtood formerly on an iſthmus, which is now a real iſland, about 100 paces from the land. The eaſt and weſt walls fell; but the north and ſouth walls ſtill re⯑main. The city, which is near ten miles from the caſtle, was overthrown ſoon after. The earth opened in many places, attended with ſub⯑terraneous noiſes; and five or ſix dreadful ſhocks were felt before the approach of night, the laſt of which laſted about half a minute. The veſ⯑ſels in the roads were greatly agitated; the ground on which the town ſtood ſunk two feet; and not above a fourth of the houſes withſtood the concuſſion, and thoſe were moſtly founded on rock. From fifteen to twenty thouſand lives were loſt†. In 1695, an earthquake was felt at Bologna in Italy; and it was remarked, as a ſingular phaenomenon, that the ſea was much troubled the day preceeding‡.
'On the 4th of May 1614, a terrible earth⯑quake happened at Tercera, which, beſides private houſes, overturned eleven churches and nine chapels in the city of Angra; and the city of Praya was ſo much ſhaken, that [422] hardly a houſe was left ſtanding: And, on the 15th of June 1628, the iſland of St Mi⯑chael was viſited with a great earthquake. Near this iſland, in the open ſea, there a⯑roſe a new iſland in a place where the water was 150 fathoms deep. This iſland was more than a league and a half long, and above ſix fathoms high*.'
'In the iſland of St Michael, another earth⯑quake began on the 26th of July 1691, and continued to the 12th of the following month. Tercera and Fayal were ſhaken next day with ſuch violence, that they ſeemed to turn about; theſe concuſſions, however, were repeated there only four times: But, at St Michael, they ceaſed not a moment during the ſpace of eleven days. The iſlanders abandoned their houſes, which every where tumbled down be⯑fore their eyes, and remained the whole time in the open fields, expoſed to the injuries of the weather. The whole town of Villa Fran⯑ca was overturned to the foundation, and moſt of the inhabitants were buried under its ruins. In ſeveral places, the plains were elevated into hills, and, in others, the hills ſunk down into vallies. A fountain of freſh water iſſued from the ground, and run for four days, and then ſtopped all of a ſudden. The air and the ſea were in ſuch commotion, that they made a noiſe reſembling the bellowings of ferocious [423] animals. Many people died of fear. There was not a veſſel in the harbours which were not agitated in a dangerous manner; and thoſe which lay at anchor, or were under ſail, at the diſtance of twenty leagues, were ſtill more roughly handled. Earthquakes are very fre⯑quent in the Azores: Twenty years before, a mountain in St Michael was overturned by this dreadful calamity†.'
'In the month of September 1627, an earth⯑quake levelled one of the two mountains of Manilla, called Carvallos, in the province of Cagayon. In 1645, a third part of the city was deſtroyed by a ſimilar accident, and 300 perſons periſhed in the ruins. The following year it was viſited by another; and the old Indians tell us, that earthquakes are now leſs dreadful than formerly; but they ſtill build their houſes of wood, in which they are imi⯑tated by the Spaniards.'
'The number of volcano's in this iſland con⯑firms the above relation; for, at certain inter⯑vals, they vomit forth flames, ſhake the earth, and produce all the effects aſcribed by Pliny to the eruptions of Veſuvius, ſuch as, chan⯑ging the beds of rivers, making the neighbour⯑ing parts of the ſea retreat, covering the pla⯑ces adjacent with aſhes, projecting ſtones to great diſtances, and making reports louder than thoſe of cannons‡.'
[424] 'In 1646, an earthquake ſplit a mountain in the iſland of Machian, and the exploſion made a frightful noiſe. From the cleft iſſued ſuch a quantity of flames as conſumed ſeveral plan⯑tations with their inhabitants. This prodi⯑gious aperture was to be ſeen in the year 1685, and it probably remains to this day. It was called the Wheel-track of Machian, becauſe it ran from the top to the bottom of the moun⯑tain, and, at a diſtance, had the appearance of a high road‡.'
The hiſtory of the French Academy mentions, in the following terms, the earthquakes which happened in Italy during the years 1702 and 1703. 'They began in October 1702, and con⯑tinued till July 1703. The city of Norcia, with its dependencies in the eccleſiaſtical ſtate, and the province of Abruzzo, ſuffered moſt; and the earthquakes were firſt felt in thoſe places which are ſituated at the foot of the Appennines, on the ſouth ſide.'
'They were frequently accompanied with frightful noiſes in the air; and theſe noiſes were ſometimes heard when the earth was at reſt, and the ſky ſerene. The moſt violent concuſſion was on the 2d of February 1703; and it was attended, eſpecially at Rome, with a remarkably clear ſky, and a great calmneſs in the air. At Rome it laſted half a minute, and at Aquila, the capital of Abruzzo, three [425] hours. Beſides ravaging the neighbouring country, it deſtroyed the whole of Aquila, and buried 5000 perſons under its ruins.'
'The concuſſions, or vibrations of the earth, as was diſcovered by the motion of the lamps in the churches, were nearly from ſouth to north.'
'The earth opened in two places, and diſ⯑charged with violence great quantities of ſtones, which covered the whole field, and rendered it barren. After the ſtones, theſe apertures threw up water above the elevation of the higheſt trees. This diſcharge continued a quarter of an hour, and laid the neighbour⯑ing country under water. The water was whitiſh, like ſoap-ſuds, and had no particular taſte.'
'On the top of a mountain near Sigillo, a village about 22 miles from Aquila, there was a conſiderable plain ſurrounded with rocks like a wall. The earthquake of the 2d of February converted this plain into a large unequal gulf, its greateſt diameter being 25 fathoms, and its leaſt 20. This gulf has been ſounded with ropes of 300 fathoms, without reaching the bottom. At the time that this gulf was formed, flames were obſerved to iſſue out of the mountain, and afterwards a thick ſmoke, which continued, with ſome interrup⯑tions, for three days.'
[426] 'At Genoa they had two ſlight concuſſions on the 1ſt and 2d days of July 1703, the laſt of which was only felt by the people on the Mole. The ſea, at the ſame time, ſunk 6 feet in the port, and continued in this ſituation a quarter of an hour.'
'The ſulphureous water on the road between Rome and Trivoli ſunk two feet and a half, both in the baſin and in the canal. The ſprings and rills of water which rendered many places of the plain called Teſtine marſhy, were entirely dried up. The depth of the water in the lake called l' Enfer was diminiſhed three feet. In place of the old ſprings, new ones, about a mile diſtant, appeared: They are probably the ſame waters, the courſes of which have been changed by the concuſſion of the earth*.'
The ſame earthquake, which, in 1538, form⯑ed the Monte di Cinere near Puzzoli, filled the Lucrin lake with ſtones, earth, and aſhes, and converted it into a marſh†.
'Earthquakes, alſo,' ſays Mr Shaw, 'have ſometimes been felt at ſea. In the year 1724, when I was aboard the Gazella, an Algerine cruiſer of 50 guns, bound to Bona to relieve the garriſon, we felt three prodigious ſhocks, one after another, as if a weight, at each time, of 20 or 30 ton, had fallen from a great height upon the ballaſt. This happened when we [427] were five leagues to the ſouthward of the Seven Capes, and could not reach ground with a line of 200 fathom. The captain told me, that, a few years before, when he was upon a cruiſe, he felt a much greater one, at the diſtance of 40 leagues to the weſtward of the rock of Liſ⯑bon†.'
Schouten, ſpeaking of an earthquake which happened in the Moluccas, ſays, that the moun⯑tains were ſhaken, and that the veſſels at anchor in 30 or 40 fathom water, were ſhocked, as if they had run aſhore, or ſtruck againſt rocks. 'We learn,' continues he, 'from daily experi⯑ence, that the ſame happens in the ocean, where no bottom can be found; and that earth⯑quakes agitate veſſels, even when the ſea is perfectly calm‡.'
Gentil, in his voyage round the world, has the following remarks upon earthquakes: '1. That, half an hour before the earth begins to ſhake, all animals appear to be ſeized with a panic. The horſes neigh, break their halters, and run out of the ſtable; the dogs bark; the birds, as if ſtupid, fly for ſhelter into the houſes; the rats and mice come out of their holes, &c. 2. That ſhips at anchor are ſo violently agitated, that all the parts of which they are compoſed ſeem to be torn aſunder; their guns break looſe, and their maſts ſpring: Theſe facts I ſhould hardly have credited, if [428] they had not been confirmed to me by the unanimous teſtimony of many witneſſes. I know that the bottom of the ſea is a continu⯑ation of the land; and that agitations of the one muſt be communicated to the other; but I could not comprehend how the different parts of a veſſel, ſwimming in a fluid, ſhould be affected in the ſame manner as if ſhe had been reſting on the ground. Her motion, I imagined, ſhould have only reſembled that produced by a ſtorm; beſides, in the preſent inſtance, the ſurface of the ſea was ſmooth, and the whole agitation muſt have proceeded from ſome internal cauſe, becauſe, at the time of the earthquake, there was no wind. 3. That, if the cavern of the earth which con⯑tains the ſubterranean fire, runs from north to ſouth, and if the buildings of a town above it lie in the ſame direction, the whole houſes are overturned; but, if the vein or cavern runs acroſs the town, the damage produced by the earthquake is leſs conſiderable†.'
When a new volcano breaks out in countries ſubject to earthquakes, they almoſt entirely ceaſe, and are ſeldom felt, except during great erup⯑tions, as has been obſerved with regard to the iſland of St Chriſtophers‡.
The enormous ravages produced by earth⯑quakes have induced ſome naturaliſts to imagine, [429] that mountains, and all the other irregularities on the ſurface of the globe, have derived their origin from ſuccuſſions of the earth occaſioned by the action of ſubterraneous fires. This, for in⯑ſtance, is the opinion of Mr Ray. He believes that all the mountains have been formed by earthquakes, or by the exploſions of volcano's, in the ſame manner as Monti di Cinere in Italy, the new iſland near Santorini, &c. But he has not conſidered, that the ſmall elevations formed by earthquakes, or by the eruptions of volcano's, are not, like all other mountains, compoſed of horizontal ſtrata; for, by digging into the Mon⯑ti di Cinere, we find calcined ſtones, aſhes, burnt earth, iron-droſs, pumice-ſtones, all blended together like a heap of rubbiſh. Beſide, if earth⯑quakes and ſubterraneous fires had raiſed the great mountains of the earth, as the Cordeliers, Mount Taurus, the Alps, &c. the prodigious force requiſite to elevate theſe enormous maſſes would, at the ſame time, have deſtroyed a great part of the ſurface of the globe. Earthquakes ſufficient to produce ſuch effects, muſt have been inconceivably violent, ſince the greateſt of them recorded in hiſtory have not been able to produce a ſingle mountain. In the reign of Valentinian I. for inſtance, an earthquake was felt over the whole known world†, and yet not a mountain was raiſed by it.
[430] It is capable of demonſtration, however, that, though an earthquake ſhould have a force ſuffi⯑cient to raiſe the higheſt mountains, this force would not be able to diſplace the reſt of the globe.
For, let it be ſuppoſed, that the chain of high mountains which traverſe South America from the point of Terra Magellanica to New Grana⯑da and the Gulf of Darien, had been ſuddenly elevated by an earthquake, and then let us eſti⯑mate the effect of this exploſion. This chain of mountains is about 1700 leagues long, and, at a medium, 40 leagues broad, including the Si⯑erres, which are lower than the Andes. This gives a ſurface of 68,000 ſquare leagues. The thickneſs of the matter diſplaced by the earth⯑quake I ſuppoſe to be one league; or, that the mean height of the mountains from their ſummits to the caverns, which, agreeable to this hypo⯑theſis, muſt ſupport them, is one league. The force of the exploſion, therefore, muſt have ele⯑vated, to the height of a league, a quantity of earth equal to 68,000 cubic leagues. But, ac⯑tion and reaction being equal, this exploſion muſt have communicated an equal quantity of motion to the whole globe. Now, the whole globe conſiſts of 12,310,523,801 cubic leagues. From this number take 68,000, and there re⯑mains 12,310,455,801 cubic leagues, of which the quantity of motion would be equal to that of 68,000 elevated one league. Hence it appears, [431] that the force neceſſary to raiſe 68,000 cubic leagues would not be ſufficient to diſplace the whole globe a ſingle inch.
There is no abſolute impoſſibility, therefore, in the ſuppoſition, that the mountains have been raiſed by earthquakes, were it not evident, both from their internal ſtructure and their external figure, that they have been formed by the ope⯑ration of the waters of the ocean. Their inte⯑rior parts are compoſed of parallel ſtrata, inter⯑ſperſed with ſea-ſhells; and their external figure conſiſts of angles every where correſponding. Is it credible that this uniform ſtructure, and regu⯑lar figure, could have been produced by ſudden and deſultory ſuccuſſions of the earth?
But, as this notion has been embraced by ſome philoſophers, and, as the nature and effects of earthquakes are not well underſtood, I ſhall hazard a few ideas, which may perhaps throw ſome light upon this intricate ſubject.
The ſurface of the earth has undergone many changes. At conſiderable depths, we find holes, caverns, ſubterraneous rivulets, and voids, which ſometimes communicate with each other by means of chinks and fiſſures. There are two ſpecies of caverns: The firſt are thoſe which have been formed by volcano's and the action of ſubterraneous fires. The action of ſubterra⯑neous fire elevates, ſhakes, and throws off to a diſtance the ſuperincumbent materials; at the ſame time, it ſplits and deranges thoſe on each [432] ſide of it, and thus produces caverns, grottos, and irregular hollows. But ſuch effects are on⯑ly exhibited in the neighbourhood of volcano's, and are not ſo frequent as the other ſpecies of caverns which are produced by the operation of water. It has already been remarked, that the different ſtrata of the earth are all interrupted by perpendicular fiſſures, the origin of which ſhall be afterwards explained. The waters that fall upon the ſurface deſcend through thoſe fiſſures, collect when their progreſs is prevented by a ſtratum of clay, and form ſprings and rivulets. From the nature of water, it ſearches for cavities or ſmall vacuities, and has a conſtant tendency to force a paſſage, till it finds a proper vent. Wherever it goes, it carries along with it ſand, gravel, and other bodies, which it is capable of dividing or diſſolving. In this manner, the o⯑peration of water proceeds till it forms ſubter⯑raneous paſſages; and then it breaks out in the form of fountains, either on the ſurface of the earth, or in the bottom of the ſea. The mate⯑rials which it perpetually carries off leave hol⯑lows or caverns in the bowels of the earth, which are often of great extent; and theſe ca⯑verns have a very different origin from thoſe produced by volcano's or earthquakes.
Earthquakes are of two kinds: The one is occaſioned by the action of ſubterraneous fires, and by the exploſions of volcano's, and are only felt at ſmall diſtances, previous to, or during the [433] time of eruptions. When the inflammable mat⯑ters in the bowels of the earth begin to ferment and to burn, the fire makes an effort to eſcape in every direction; and, if it finds no natural vents, it forces a paſſage, by elevating and throw⯑ing off the earth above it. In this manner vol⯑cano's commence, and their effects continue in proportion to the quantity of inflammable mat⯑ter they contain. When the quantity of in⯑flamed matter is inconſiderable, it produces only an earthquake, and exhibits no marks of a vol⯑cano: The air generated by ſubterraneous fire may alſo eſcape through ſmall fiſſures; and, in this caſe, likewiſe, it will be attended with a ſuc⯑cuſſion of the earth; but no volcano will appear. But, when the quantity of inflamed matter is great, and when it is confined on all ſides by ſo⯑lid and compact bodies, an earthquake and a volcano are the neceſſary conſequences. But all theſe commotions conſtitute only the firſt ſpecies of earthquakes, which are not felt but in the neighbourhood of the places where they hap⯑pen. A violent eruption of Aetna, for example, will ſhake all the iſland of Sicily; but it will never extend to the diſtance of three or four hundred leagues. When Veſuvius burſts open a new mouth, it excites an earthquake in Naples and in the neighbourhood of the volcano; but theſe earthquakes never ſhake the Alps; nor do they extend to France or other countries diſtant from Veſuvius. Thus, earthquakes produced [434] by volcano's are limited to a ſmall ſpace; they are nothing but effects of the reaction of the fire, and they ſhake the earth in the ſame manner as the exploſion of a powder-magazine occaſions an agitation to the diſtance of ſeveral leagues.
But there is another ſpecies of earthquakes, which are very different in their effects, and per⯑haps alſo in their cauſe. Theſe earthquakes are felt at great diſtances, and ſhake a long tract of ground, without the intervention either of a new volcano, or of eruptions in thoſe that al⯑ready exiſt. There are inſtances of earthquakes which have been felt at the ſame time in Britain, in France, in Germany, and in Hungary. Theſe earthquakes always extend more in length than in breadth. They ſhake a zone or belt of earth with greater or leſs violence in different places; and they are generally accompanied with a hol⯑low noiſe, like that of a heavy carriage rolling with rapidity.
As to the cauſes of this ſpecies of earthquake, it muſt be remarked, that the exploſion of all inflammable ſubſtances, like that of gun-powder, generates a great quantity of air; that this air is highly rarified by the heat; and that its effects, from the compreſſion it receives by being con⯑ſined in the bowels of the earth, muſt be exceed⯑ingly violent. Let us ſuppoſe, that, at the depth of 100 or 200 fathoms, there are a vaſt collec⯑tion of pyrites and ſulphureous bodies, and that they are inflamed by the fermentation pro⯑duced [435] by the admiſſion of water to them, or by other cauſes. What muſt be the effect? In the firſt place, thoſe ſubſtances are not placed in horizontal beds, like the antient ſtrata, which were formed by the ſediments of the waters; they are lodged, on the contrary, in the perpendicular fiſſures, in ſubterraneous caverns, and other places, to which the water has ac⯑ceſs. When inflamed, they generate a vaſt quantity of air, the ſpring of which, by be⯑ing compreſſed in a ſmall ſpace, like that of a cavern, will not ſhake the earth immediately a⯑bove, but it will ſearch for paſſages in order to expand and make its eſcape. Caverns, and the channels of ſubterraneous rivulets and ſprings, are the only natural paſſages for this rarified air. Into theſe, therefore, it will ruſh with impetuo⯑ſity, and produce in them a furious wind, the noiſe of which will be heard on the ſurface; and it will be attended with vibrations or ſuccuſſions of the ground. This ſubterraneous wind pro⯑duced by fire, will extend the whole length of the caverns or channels, and occaſion a ſhaking, more or leſs violent, in proportion to its diſtance from the heat, and to the width or narrowneſs of the canals. But this motion muſt neceſſarily run in a longitudinal direction; and the ſhaking, of courſe, muſt be felt over a long belt of ground. This air, however, cannot produce an eruption or a volcano; becauſe it finds ſufficient room for expanding itſelf, and diminiſhing its force; or rather, becauſe it eſcapes through fiſſures in [436] the form of vapour or of wind. But, although the exiſtence of caverns or channels for the paſ⯑ſage of this rarified air ſhould be denied, it is eaſy to conceive, that, in the very place where the exploſion is made, as the earth is elevated to a conſiderable height, the neighbouring places muſt ſplit horizontally in attempting to yield to the impulſe communicated by the original mo⯑tion; and, in this manner, paſſages may be gra⯑dually and ſucceſſively opened, ſo as to commu⯑nicate with very diſtant places. This explica⯑tion correſponds with all the phaenomena. Earth⯑quakes are not felt at great diſtances at the ſame minute, or even the ſame hour. They are not accompanied with eruptions or external fire; and the noiſe almoſt conſtantly marks the pro⯑greſſive motion of this ſubterraneous wind. O⯑ther facts concur in eſtabliſhing this theory. Blaſts of wind, and vapours, ſometimes of a ſuf⯑focating nature, it is well known, ariſe from mines, independent of the motion in the air pro⯑duced by the current of water. It is equally well known, that winds iſſue from certain aper⯑tures of the earth, from caverns, abyſſes, and deep lakes, as lake Boleſlaw in Bohemia, which we have formerly mentioned.
When theſe remarks are conſidered, I cannot comprehend how the mountains ſhould have o⯑riginated from earthquakes, ſince the mineral and ſulphureous bodies which occaſion them are ſeldom to be met with but in the perpendicu⯑lar [437] fiſſures of mountains, and in other cavities of the earth, the greateſt number of which have been produced by the operation of water; ſince thoſe inflammable ſubſtances produce only a mo⯑mentary exploſion, and violent winds which fol⯑low the channels of ſubterraneous waters; ſince the duration of earthquakes on the ſurface of the earth is ſo ſhort, they muſt be occaſioned by a ſudden exploſion, and not by a continued con⯑flagration; and, laſtly, ſince thoſe earthquakes, which extend over large tracts of ground, never produce the ſmalleſt eminence throughout their whole courſe.
Earthquakes, it is true, are more frequent in the neighbourhood of volcano's, as in Sicily, and the environs of Veſuvius: But it appears, from repeated obſervation, that theſe earthquakes are very limited, and, conſequently, can never form a chain of mountains.
It has ſometimes been remarked, that the matters ejected from Aetna, after cooling for ſe⯑veral years, and being afterwards moiſtened with rain, have rekindled, and thrown out flames with ſuch violent exploſions, as to occaſion ſmall earthquakes.
In 1669, during a violent eruption of Etna, which began on the 11th of March, the ſummit of the mountain ſunk conſiderably*; which is a proof that this volcano proceeds rather from the ſuperior part of the mountain than from the bottom of it. Borelli, who is of the ſame [438] opinion, obſerves, 'That the fire of a volcano proceeds neither from the centre, nor from the bottom of a mountain, but from the top; and that the inflammation never kindles but at a ſmall depth*.'
Mount Veſuvius has frequently thrown out, during eruptions, great quantities of boiling wa⯑ter. Mr Ray, who imagines that the fire of volcano's comes from a very great depth, ſays, that this water proceeds from the ſea, which com⯑municates, by ſubterraneous paſſages, with the foot of the mountain. As a proof, he mentions the remarkable dryneſs of the top of Veſuvius, and the agitation of the ſea during eruptions, which ſometimes recedes ſo far as to leave the port of Naples entirely dry. But, ſuppoſing theſe facts to be true, they by no means prove that the fire of volcano's proceeds from a great depth; for the water they eject is certainly rain⯑water, which penetrates through the fiſſures, and collects in the cavities of the mountain. Rills and ſprings iſſue from the tops of volcano's as well as from other high mountains; and, as the former are hollow, and have ſuffered more con⯑cuſſions than the latter, nothing can be more na⯑tural than they ſhould collect water in their ca⯑verns, and that theſe waters ſhould ſometimes be ejected, along with other ſubſtances, in the time of eruptions. With regard to the motion of the ſea, it ariſes ſolely from the ſhock com⯑municated [439] to the waters by the exploſion, which makes it advance or retire according to different circumſtances.
The moſt common ſubſtances thrown out by volcano's, are torrents of melted minerals, which overflow the environs of the mountain. Theſe rivers of lava extend to great diſtances; and, in cooling, they form beds, either horizontal or in⯑clined, in the ſame manner as the ſtrata accumu⯑lated by ſucceſſive ſediments from water; but the former are eaſily diſtinguiſhable from the latter: 1. Becauſe ſtrata of lava are not every where equal in thickneſs. 2. Becauſe they con⯑tain nothing that has not evidently been cal⯑cined, vitrified, or melted. 3. Becauſe their extent is more limited. As there is a vaſt num⯑ber of volcano's in Peru, and, as the bottoms of moſt of the Cordeliers are covered with ſubſtan⯑ces that have been thrown out by eruptions, it is not ſurpriſing that no ſea-ſhells have been found there; for they muſt have been calcined and deſtroyed by the fire. But I am ſtill per⯑ſuaded, that, if the clay ground, which, accor⯑ding to M. Bourguet, is the ordinary earth in the valley of Quito, had been dug, ſhells would have been diſcovered there, as well as every where elſe, eſpecially where the ground is not covered, like the bottoms of the mountains, with matters ejected from volcano's.
It has often been aſked, Why all volcano's appear only on high mountains? I have partly [440] ſolved this queſtion in the preceding article. But, before finiſhing the preſent ſubject, I ſhall endeavour more fully to explain myſelf.
The peaks or points of mountains were ori⯑ginally covered with earth and ſand, which, af⯑ter being gradually waſhed down to the vallies by the rains, left nothing but thoſe bare rocks or ſtones called the core of mountains, which, being likewiſe ſubjected to the action of the weather, ſmall and large fragments of them muſt have been occaſionally looſened, and, of courſe, muſt have rolled down to the plains. The rocks at the baſe of the ſummit being fully uncovered, and having loſt their original ſupport from the ſand and earth, would neceſſarily give way a little, and, by ſeparating from each other, would produce ſmall intervals. But this yielding of the lower rocks could not take place without rending thoſe that lay above them. In this man⯑ner the core of the mountain, from the ſummit to the baſe of the lower rocks, would be ſplit into an infinite number of perpendicular fiſſures of different dimenſions. Through theſe the rains would penetrate and carry along with them, into the bowels of the mountain, all the minerals, and other ſubſtances which they were capable of tranſporting or diſſolving. Here pyrites, ſul⯑phur, and other combuſtible ſubſtances, would be produced; and, in the courſe of time, theſe bo⯑dies would accumulate in great quantities, and, by their fermentation, would give riſe to explo⯑ſions [441] and other effects of volcano's. Heaps of theſe mineral ſubſtances might likewiſe exiſt in the heart of the mountain, before the rain could penetrate ſo deep. In this caſe, as ſoon as the air or rain got acceſs to them by means of the perpendicular fiſſures, a conflagration and vol⯑cano would inſtantly take place. No ſuch phae⯑nomena can be exhibited in plains; for, as every thing there is at reſt, and nothing can be diſ⯑placed, it is not ſurpriſing that the exiſtence of volcano's ſhould be confined entirely to the mountains.
When coal-mines are opened, which are com⯑monly found in clay-grounds, and at a great depth, the mineral ſubſtances above mentioned ſometimes kindle into flames. There are ex⯑amples in Scotland, Flanders, &c. of coal-mines which have continued to burn for many years. The admiſſion of air is alone ſufficient to pro⯑duce this effect. But theſe inflammations occa⯑ſion only ſlight exploſions, and never form vol⯑cano's; becauſe, in ſuch places, all being plain and ſolid, the fire cannot be excited to ſuch a degree as in burning mountains, which are full of caverns and cliffs, through which the air pe⯑netrates, and augments the action of the fire ſo forcibly, as to give riſe to the terrible effects we have been deſcribing.
NEW iſlands are either produced ſuddenly by the operation of ſubterraneous fires, or ſlowly by the accumulated ſediments of wa⯑ter. Upon this ſubject we are furniſhed with indubitable facts, both by antient hiſtorians, and by modern voyagers. Seneca tells us, that, in his time, the iſland of Theraſia* ſuddenly emer⯑ged from the ſea, to the aſtoniſhment of many ſpectators. Pliny relates, that 13 iſlands former⯑ly aroſe all at once from the boſom of the Me⯑diterranean, and that Rhodes and Delos are the chief of them. According to Ammianus Mar⯑cellinus, Philo, Pliny, &c. theſe 13 iſlands were [443] not formed by an earthquake or by a ſubterra⯑neous exploſion, but were formerly concealed under the water, which ſunk and uncovered them. Delos was even diſtinguiſhed by the name of Pelagia, becauſe it formerly belonged to the ſea. Whether theſe 13 new iſlands were produced by the action of ſubterraneous fire, or by any other cauſe which diminiſhed the quan⯑tity of water in the Meditterranen, it is not ea⯑ſy to determine. But we are informed by Pli⯑ny himſelf, that the iſland of Hiera, in the neigh⯑bourhood of Theraſia, is compoſed of ferrugi⯑nous maſſes, and of earth which had been thrown up from the bottom of the ſea; and, in another place, he mentions ſeveral other iſlands which had been formed in the ſame manner. Upon this ſubject, however, we have facts more re⯑cent, and leſs involved in obſcurity.
On the 23d day of May 1707, at ſun-riſing, there appeared, at the diſtance of two or three miles from the iſland of Theraſia or Santorini, ſomething which had the reſemblance of a float⯑ing rock. Some men, ſtimulated by curioſity, approached it, and diſcovered that it had ariſen from the bottom of the ſea; that it increaſed under their feet; that oiſters and other ſhells ſtill adhered to the rocks; and that many pumice⯑ſtones lay on its ſurface. Two days before this rock appeared, there had been a ſlight earthquake in Santorini. This iſland continued to augment conſiderably, without any accident, till the 14th [444] of June; it was then about half a mile in cir⯑cumference, and 20 or 30 feet high, and the earth was white, and mixed with clay. After this, the ſea began to be more and more agita⯑ted; vapours aroſe from it which infeſted the iſland of Santorini, and, on the 16th of July, 17 or 18 rocks roſe all at once from the bottom of the ſea, and united into one maſs. Theſe phaenomena were attended with a frightful noiſe, which continued two months; and flames iſſu⯑ed from the new iſland, which ſtill augmented both in circumference and height; and the ex⯑ploſions were ſo violent, that they drove large ſtones to more than 7 miles diſtance. The iſland of Santorini itſelf was regarded by the antients as a recent production; and, in 726, 1427, and 1573, it received conſiderable additions, beſide the ſmall iſlands formed in its neighbourhood*. The ſame volcano, which, in the days of Seneca, raiſed the iſland of Santorini, produced, in Pli⯑ny's time, that of Hiera or Volcanella, and, in our days, the rock above deſcribed.
On the 10th of October 1720, a great fire was ſeen to ariſe from the ſea near the iſland of Tercera. Navigators being ſent, by order of go⯑vernment, to examine it, they perceived, on the 19th of the ſame month, an iſland, conſiſting of fire and ſmoke; and a prodigious quantity of aſhes, thrown to a great diſtance, as from a vol⯑cano, accompanied with a noiſe ſimilar to that [445] of thunder. The earth was alſo perceived to ſhake in the neighbourhood; and a vaſt number of pumice-ſtones were found floating on the ſea all round the new iſland: This laſt phaeno⯑menon has ſometimes been remarked in the o⯑pen ſea*.
The hiſtorian of the French academy†, in narrating this event, remarks, that, after an earthquake in the iſland of St Michael, one of the Azores, there appeared a torrent of fire be⯑tween this iſland and that of Tercera, which gave riſe to two new rocks: And, in the ſub⯑ſequent year, the ſame hiſtorian gives the fol⯑lowing detail:
'M. de l'Iſle has informed the academy of ſeveral particulars concerning the new iſland among the Azores, which he received in a letter from M. de Montagnac conſul at Liſ⯑bon. On the 18th of September 1721, M. de Montagnac's veſſel was moored off the fortreſs of St Michael; and he learned the following particulars from the pilot of the port.'
'During the night of the 7th or 8th of De⯑cember 1720, there was a great earthquake in Tercera and St Michael, which iſlands are di⯑ſtant from each other about 28 leagues, and a new iſland roſe from the ſea. It was, at the ſame time, remarked, that the point of the iſland of Peak, at the diſtance of 30 leagues, [446] which formerly threw out flames, was extin⯑guiſhed. But a continual thick ſmoke iſſued from the new iſland, which was diſtinctly perceived by M. de Montagnac, as long as he continued in that part. The pilot aſſured him, that he had ſailed round the iſland, and approached it as near as he could with ſafety. He ſound⯑ed on the ſouth ſide of it with a rope of 60 fathoms; but found no bottom. On the weſt ſide, the water was much changed: It ap⯑peared to be mixed with white, blue, and green; and, at the diſtance of two miles, it ſeemed to be ſhallow and boiling. On the north-weſt, the ſide from which the ſmoke iſſued, he found, at 15 fathoms, a bottom of coarſe ſand. He threw a ſtone into the ſea, and, at the place where it fell, he obſerved the water boil, and mount into the air with great impetuoſity. The bottom was ſo hot, that, at two different times, it melted a piece of ſuet which had been faſtened to the end of the plumb-line. The pilot likewiſe remarked, that ſmoke iſſued from a ſmall lake, in the midſt of a ſandy plain. This iſland is nearly round, and high enough to be perceived, in clear weather, at the diſtance of ſeven or eight leagues.'
'We have ſince learned, by a letter from M. Adrien, French conſul at St Michael, dated in March 1722 that the new iſland is conſi⯑derably diminiſhed; that it is nearly on a [447] level with the water; and that it will probably ſoon diſappear.'
From theſe, and many other facts of a ſimilar nature, it is apparent, that inflammable bodies exiſt under the bottom of the ſea, and that they ſometimes produce violent exploſions. The places where they happen may be conſidered as ſubmarine volcano's, which differ from com⯑mon volcano's only in the ſhorter duration of their effects; for, after the fire opens a paſſage to itſelf, the water ruſhes in, and extinguiſhes them. The elevation of new iſlands neceſ⯑ſarily leaves caverns, which are ſoon filled by the waters; and the new ground, which conſiſts of matter thrown out by the ſubmarine volcano, muſt, in every reſpect, reſemble that of the Monte di Cinere, and other eminences which have been raiſed by terreſtrial volcano's. It is on account of the water's ruſhing into the voids and fiſſures produced by exploſions, that ſub⯑marine volcano's exhibit their effects leſs fre⯑quently than common volcano's, though both derive their origin from the ſame cauſe.
To ſubterraneous, or rather ſubmarine fires, muſt be aſcribed all thoſe ebullitions of the ſea, and water-ſpouts, which have been remarked in different places by mariners: They alſo produce ſtorms and earthquakes, the effects of which are equally felt at ſea as upon land. The iſlands raiſed by ſubmarine volcano's are generally compoſed of pumice-ſtones and calcined rocks.
[448] Fire has frequently been obſerved to iſſue out of the waters of the ſea. Pliny tells us, that the whole ſurface of the Thraſymen lake has ap⯑peared to be inflamed; and Agricola informs us, that, when a ſtone was thrown into the lake of Denſtat in Thuringia, its deſcent was marked by a train of fire.
Laſtly, the great quantities of pumice-ſtones diſcovered by voyagers in different parts of the ocean, as well as in the Mediterranean, demon⯑ſtrate the exiſtence of volcano's in the bottom of the ſea, which differ not from thoſe upon land, either in the violence of their exploſions, or in the matter they throw out, but only in their rarity, and in the ſhortneſs of their dura⯑tion. Hence it may be remarked, that the bot⯑tom of the ſea every way reſembles the ſurface of the earth, not admitting even the exception of volcano's.
Between ſea and land volcano's there are many relations. Both of them exiſt on the tops of mountains. The Azore iſlands, and thoſe of the Archipelago, are only the points of mountains, ſome of which are above, and others under, the ſurface of the water. From the account of the new iſlands among the A⯑zores, it appears, that the place where the ſmoke iſſued was only 15 fathoms deep, which, when compared with the ordinary depth of the ocean, demonſtrates this place to be the top of a pretty high mountain. The ſame remark may be [449] made with regard to the new iſland near Santo⯑rini. Its depth muſt have been inconſiderable, ſince oiſters were found attached to the rocks which roſe above the ſurface of the water. It likewiſe appears, that ſea-volcano's, as well as thoſe upon land, have ſubterraneous communi⯑cations; for, at the very time that the new iſland among the Azores aroſe, the ſummit of the volcano of St George, in the iſland of Peak, ſunk. It alſo merits obſervation, that new iſlands never appear but in the neighbourhood of old ones; and that there are no examples of new iſlands in open ſeas: They ought, there⯑fore, to be regarded as continuations of the an⯑tient iſlands; and, when volcano's happen to exiſt in the latter, it is not ſurpriſing that the for⯑mer ſhould contain the ſame materials, which may be kindled either by fermentation alone, or by the action of ſubterraneous winds.
Beſides, new iſlands produced by earthquakes, or by ſubterraneous fires, are few in number. But the number of thoſe formed by ſlime, ſand, and earth, tranſported by rivers, or by the mo⯑tions of the ſea, is almoſt infinite. At the mouths of rivers, ſuch quantities of earth and ſand are amaſſed, as frequently give riſe to iſlands of conſiderable extent. The ſea, by re⯑tiring from certain coaſts, leaves uncovered the higheſt parts of the bottom, and theſe parts con⯑ſtitute ſo many new iſlands. In the ſame man⯑ner, when the ſea encroaches upon the land, it [450] covers the plains, and the more elevated grounds appear in the form of iſlands. It is for this rea⯑ſon that there are few iſlands in the open ſeas, and that they are ſo numerous near the coaſts.
Fire and water, though of very oppoſite na⯑tures, exhibit many effects ſo ſimilar, that the one may often be miſtaken for the other. Be⯑ſide the productions peculiar to theſe elements, as chryſtal, glaſs, &c. they give riſe to many great phaenomena, which have ſuch ſtrong re⯑ſemblances, that they can hardly be diſtinguiſh⯑ed. Water, as we have ſeen, elevates moun⯑tains, and forms the greateſt number of iſlands: Some mountains and iſlands likewiſe derive their origin from fire. The ſame obſervation applies to caverns, fiſſures, gulfs, &c. Some of them are the effects of fire, and others of water.
Caverns are, in a great meaſure, peculiar to mountains: They are ſeldom or never found in plains. They are frequent in the Archipelago, and other iſlands; becauſe iſlands are generally nothing but the tops of mountains. Caverns, like precipices, are formed by the ſinking or mouldering of rocks, or, like abyſſes, by the action of fire; for, to make a cavern form a precipice or an abyſs, nothing farther is neceſ⯑ſary than that the tops of the oppoſite rocks ſhould come together and form an arch, which muſt frequently happen when they are looſened at the root, and ſhaken by earthquakes, or by the operation of time and of the weather. Ca⯑verns [451] may be produced by the ſame cauſes which give riſe to gulfs, apertures, or ſinkings of the earth; and theſe cauſes are exploſions of vol⯑cano's, the action of ſubterraneous vapours, and earthquakes, which create ſuch commotions in the earth as muſt neceſſarily produce caverns, fiſſures, and hollows of every kind.
The cavern of St Patrick in Ireland is not ſo conſiderable as it is famous: The ſame remark may be made with regard to the Grotto del Cane in Italy, and to that of Mount Beni-guazeval, in the kingdom of Fez, which throws out fire. There is a very large cavern in the county of Derby in England. It is much larger than the celebrated cavern of Bauman, near the Black Foreſt of Brunſwick. I was informed by the Earl of Morton, a philoſopher more reſpectable for his merit than his high rank, that the en⯑trance to this cavern, called the Devil's hole, is larger than the door of any church; that a ſmall river runs through it; that, after advan⯑cing ſome way, the vault of the cavern ſinks down ſo low, that, in order to proceed farther, it is neceſſary to lie flat in a boat, and to be puſhed through this narrow paſſage by people accuſtomed to the buſineſs; and that, after get⯑ting through, the roof, or arch of the cavern, riſes to a great height; and, after walking a con⯑ſiderable way on the ſide of the river, the arch ſinks again ſo low as to touch the ſurface of the water. Here the cavern terminates. The river, [452] which ſeems to have its ſource in this part of the cavern, ſwells occaſionally, and tranſports heaps of ſand, which, by accumulating, forms a kind of blind alley, whoſe direction is different from that of the principal cavern.
In Carniola, near Potpechio, there is a large cavern, in which is a pretty conſiderable lake. Near Adelſperg, we meet with a cavern in which a man may travel two German miles. It contains ſeveral tremendous and deep precipices*. The Mendip hills in Somerſet-ſhire likewiſe preſent us with extenſive caverns, and very fine grottos. Near theſe caverns we find veins of lead, and ſometimes large oak-trees, buried 15 fathoms deep. In the county of Glouceſter, there is a large cavern called Pen-park-hole, at the bottom of which we meet with 32 fathoms of water. Here we alſo find veins of lead.
It is apparent, that the Devil's-hole, and o⯑ther caverns, from which iſſue large ſprings or brooks, have been gradually formed by the ope⯑ration of the water, and their origin cannot be aſcribed to earthquakes or volcano's.
One of the largeſt and moſt ſingular caverns we are acquainted with, is that of Antiparos, of which M. Tournefort has given a complete de⯑ſcription. We firſt find a ruſtic cave about 30 feet wide, divided by ſome natural pillars. Be⯑tween two pillars on the right, the ground ſlops gently, and then more precipitately for about [453] 20 paces to the bottom of the cavern. This is the paſſage to the grotto or interior cave, and is nothing but a dark hole, through which a man cannot paſs without ſtooping, and the aſſiſtance of lights. We then deſcend, by means of a rope fixed at the entrance, a horrible precipice, and arrive on the very borders of another ſtill more tremendous, with correſponding abyſſes on the left. By a ladder placed on the margin of theſe gulphs, we get over a vaſt perpendicular rock. We then continue to ſlip through places leſs dangerous. But, when we think ourſelves in the greateſt ſafety, we are ſuddenly ſtopped by a frightful paſs; to eſcape through which, we are obliged to glide on our backs along a large rock, and to deſcend by means of a ladder. When we arrive at the bottom of the ladder, we ſtumble for ſome time among irregular rocks, and then the famous grotto preſents itſelf. This grotto is about 300 fathoms below the ſurface of the earth, and it appears to be about 40 fa⯑thoms high, and 50 wide. It is full of large and beautiful ſtalactites, which both depend from the roof of the vault and cover the floor*.
In that part of Greece called Achaia by the antients, now Livadia, there is a large cavern in a mountain which was formerly famous for the oracles of Trophonius: It is ſituated between the Lake of Livadia and the ſea, from which, at the neareſt part, it is diſtant about four miles; and [454] there are no leſs than 40 ſubterraneous paſſages through which the waters run under the moun⯑tain*.
In all countries that are ſubject to earthquakes or volcano's, caverns are frequent. The ſtructure of moſt of the iſlands of the Archipelago is ex⯑ceedingly cavernous. The iſlands in the Indian ocean, and particularly the Moluccas, appear to be chiefly ſupported upon vaults. The land of the Azores, of the Canaries, of the Cape de Verd iſlands, and, in general, of almoſt all ſmall iſlands, is, in many places, hollow and full of caverns; becauſe theſe iſlands, as formerly re⯑marked, are only the tops of mountains, which have ſuffered great convulſions either from vol⯑cano's, or by the action of the waters, of froſts, and of other injuries of the weather. In the Cordelieres, where volcano's and earthquakes are frequent, there are many caverns, precipices, and abyſſes.
The famous labyrinth in the iſland of Crete is not the work of nature alone. We are aſſured by M. Tournefort, that, in many parts of it, the operation of men is evident; and, it is probable, that this is not the only cavern which has been augmented by art. Mines and quarries are con⯑ſtantly digging; and, after theſe have been long deſerted, it is not eaſy to determine whether ſuch excavations have been the effects of nature or of art. Some quarries are amazingly exten⯑ſive. [455] That of Maeſtricht, for inſtance, is ſuffi⯑cient to ſhelter 50,000 men, and is ſupported by more than 1000 pillars of 20 feet high; and the earth and rock above is 25 fathoms thick*. The ſalt mines of Poland exhibit excavations ſtill more extenſive. Near large cities, quarries and artificial hollows are common. But, we muſt proceed no farther in detail. Beſides, the opera⯑tions of men, however great, will always make but an inconſiderable figure in the hiſtory of nature.
Volcano's and water which form caverns in the bowels of the earth, produce likewiſe on its ſurface, fiſſures, precipices, and abyſſes. At Cajeta in Italy, there is a mountain which had been formerly ſplit by an earthquake in ſuch a manner, that the ſeparation ſeems to have been made by the hands of men. We have already mentioned the Wheel-track, or great fiſſure in the iſland of Machian, the abyſs of Mount Ara⯑rat, the port or gap in the Cordelieres, that of Thermopylae, &c. To theſe we might add the gap in the mountain of the Troglodites in Arabia, and that of the Ladders in Savoy, which was begun by nature, and finiſhed by Victor-Ama⯑daeus. Conſiderable ſinkings in the earth, the fall of rocks, and the ſubverſion of mountains, are frequently produced by the waters, as well as by ſubterraneous fires. Of this many ex⯑amples might be given.
[456] 'In the month of June 1714, a part of the mountain of Diableret in Valois fell ſudden⯑ly, and, in a few hours, the ſky being ſerene, it appeared to have aſſumed a conical figure. It deſtroyed 55 houſes, beſides ſeveral men, and a great many cattle; and it covered a league ſquare with its ruins. The ſky was darkened with the duſt; the collection of ſtones and earth that were amaſſed on the plain, exceeded 30 Rheniſh perches in height, dammed up the waters, and gave riſe to new lakes of conſide⯑rable depths. But this phaenomenon was not accompanied with the leaſt veſtige of bitumen, ſulphur, or calcined lime-ſtone; nor, conſe⯑quently, of ſubterraneous fire: The baſe of this great rock appeared to be rotten, and re⯑duced to powder*.'
There is a remarkable example of theſe ſink⯑ings near Folkſtone in the county of Kent. The hills in the neighbourhood ſunk inſenſibly, with⯑out any earthquake or other commotion. The interior parts of theſe hills conſiſt of rocks and chalk; and, by their ſinking, they have puſhed part of the adjacent land into the ſea. A well atteſted relation of this fact may be ſeen in the Philoſophical Tranſactions†.
In 1618, the town of Pleurs was buried un⯑der the rocks at the foot of which it had been ſituated. In 1678, a great inundation was oc⯑caſioned, [457] in Gaſcony, by the ſinking of ſome portions of one of the Pyrenees, which forced out the water that had been pent up in the ſub⯑terraneous caverns of theſe mountains. In the year 1680, a ſtill greater inundation was pro⯑duced in Ireland, by the ſinking of a mountain into caverns that had been full of water. It is not difficult to inveſtigate the cauſe of theſe ef⯑fects. It is well known, that ſubterraneous wa⯑ters are every where frequent. Theſe waters gradually work away ſand and earth in their paſſages; and, conſequently, they may, in the courſe of time, deſtroy the ſtratum of earth which ſerves as a baſis to the mountain: If this ſtratum fail more on one ſide than on another, the mountain muſt, of neceſſity, be overturned; or, if the baſe waſtes gradually and equally throughout, the mountain will ſink, without be⯑ing overturned.
Having mentioned a few of thoſe convulſions and changes produced in the earth by what may be called the accidents of nature, we muſt not paſs over in ſilence the perpendicular fiſſures in the different ſtrata. Theſe fiſſures are obvious, not only in all rocks and quarries, but in clays, and in every ſpecies of earth which has never been removed from its natural poſition. They are called perpendicular fiſſures; becauſe, like the horizontal ſtrata, they are never oblique, but from ſome accidental change. Woodward and Ray talk of fiſſures, but in a general and confuſed [458] manner, and they never mention them under the appellation of perpendicular fiſſures, becauſe they imagined that they might be indifferently either oblique or perpendicular. No author has hitherto attempted to explain their origin, though it is apparent, as remarked in a former article, that they have been occaſioned by the drying of the materials which compoſe the horizontal ſtra⯑ta. In whatever manner this drying ſhould hap⯑pen, perpendicular fiſſures muſt have been a ne⯑ceſſary conſequence of it; for the matter of the horizontal ſtrata could not be diminiſhed in ſize, without ſplitting, at different diſtances, in a di⯑rection perpendicular to the ſtrata themſelves. Under perpendicular fiſſures, I comprehend, not only the natural cracks in rocks, but all thoſe ſeparations which have been effected by convul⯑ſive accidents. When a maſs of rocks have ſuf⯑ered any conſiderable motion, the fiſſures are ſometimes placed obliquely; but it is becauſe the maſs itſelf is oblique; and the ſmalleſt at⯑tention to quarries of marble and lime-ſtone, or to great chains of rocks, will convince us, that the general direction of fiſſures is perpendicular to the ſtrata in which they are found.
The bowels of mountains are chiefly compo⯑ſed of parallel ſtrata of ſtones and rocks. Be⯑tween the parallel ſtrata, we often meet with beds of matter ſofter than ſtone; and the per⯑pendicular fiſſures are filled with ſand, cryſtals, metals, &c. The formation of theſe laſt bo⯑dies [459] is more recent than that of the horizontal ſtrata in which ſea-ſhells are found. The rains have gradually detached the ſand and earth from the tops of mountains, and left the ſtones and rocks bare, which affords an opportunity of di⯑ſtinguiſhing with eaſe both the parallel ſtrata and the perpendicular fiſſures. On the other hand, the rains and rivers have ſucceſſively covered the plains with conſiderable quantities of earth, ſand, gravel, and other bodies that are either ſoluble in water, or eaſily diviſible by it. Of theſe have been formed beds of tufa, of ſoft ſtone, of ſand, of rounded gravel, and of earth mixed with ve⯑getable ſubſtances. But theſe beds contain no ſea-ſhells, or, at moſt, but fragments of them, which have been detached from the mountains along with the earth and gravel. Theſe recent beds ſhould be carefully diſtinguiſhed from the antient and original ſtrata, in which we almoſt univerſally find a great number of entire ſhells placed in their natural ſituation.
In examining the internal order and diſtribu⯑tion of the materials of a mountain, compoſed of common ſtone or calcinable lapidific matter, we generally find, after removing the vegetable ſoil, a bed of gravel, of the ſame nature and colour with the ſtones that predominate in the moun⯑tain; and, under the gravel, we meet with the ſolid rock. When the mountain is cut by a deep trench or ravine, the different banks or ſtrata are eaſily diſtinguiſhable. Each horizon⯑tal [460] ſtratum is ſeparated by a kind of joint or fu⯑ture, which is likewiſe horizontal. Theſe ſtrata generally augment in thickneſs, in proportion to their depth or diſtance from the top of the mountain; and they are all divided, vertically, by perpendicular fiſſures. In general, the firſt ſtratum under the gravel, and even the ſecond, are not only thinner than thoſe which form the baſe of the mountain, but ſo much cut by per⯑pendicular fiſſures, that only ſmall portions of them have any coherence. Moſt of theſe fiſ⯑ſures, which exactly reſemble the cracks in earth that has been dried, gradually diſappear as they deſcend, and, at the baſe of the mountain, where they cut the larger ſtrata in a more regu⯑lar and more perpendicular manner than thoſe near the ſurface, their number is much ſmaller.
Theſe ſtrata of rock often extend, without in⯑terruption, to great diſtances. Stones of the ſame ſpecies likewiſe are almoſt uniformly found in oppoſite mountains, whether they be ſepa⯑rated by a narrow neck or a valley; and the ſtrata never entirely diſappear, unleſs when the mountain terminates in a large and level plain. Sometimes we find, between the vegetable ſoil and the gravel, a ſtratum of marle, which com⯑municates its colour, and other qualities, to the neighbouring beds: The perpendicular fiſſures in the inferior rocks are, in this caſe, filled with marle, where it acquires a hardneſs equal, in ap⯑pearance, to that of the ſurrounding ſtone; but, [461] when expoſed to the air, it ſplits, and becomes ſoft and ductile.
The beds of ſtone which compoſe the top of the mountains are generally ſoft and tender, but thoſe near the baſe are exceedingly hard. The firſt is commonly white, and of a grain ſo fine as to be hardly perceptible. In proportion as they deſcend, the rocks become more compact, and have a better grain; and the loweſt beds are not only harder than the ſuperior ones, but are alſo more compact and more heavy. Their grain is fine and brilliant; and they are often ſo brittle as to break as purely and neatly as flint.
The heart of a mountain, then, is compoſed of different ſtrata of ſtones, which are harder or ſofter in proportion to their diſtance from the ſummit; and they are broad at the baſe, and ſharp and narrow at the top. The laſt is, in⯑deed, a neceſſary reſult of the firſt: For, as the ſtones grow harder as they deſcend, it is natural to think, that the currents, and other motions of the water, which ſcooped out the vallies, and formed the contours of the mountains, muſt have gradually conſumed, by their lateral fric⯑tion, the materials of which the mountains are compoſed; and that this conſumption would be proportioned to the hardneſs or ſoftneſs of the matter acted upon. But, as the upper ſtrata are known to be ſofteſt, and as their denſity increaſes according as they approach the baſe, the moun⯑tains [462] muſt, of neceſſity, have aſſumed their pre⯑ſent inclined, and ſomewhat conical figure. This is one great cauſe of the declivity of mountains; and it muſt always become more gentle, in proportion as the earth and gravel are brought down by the rain from their ſummits. For theſe reaſons it is that the declivity of hills and mountains, compoſed of calcinable bodies, is leſs than that of thoſe which conſiſt of granite, or of flint, in large maſſes. The latter generally riſe almoſt perpendicularly to very great heights; becauſe, in theſe maſſes of vitrifiable matter, the ſuperior, as well as the inferior ſtrata, are ex⯑tremely hard, and have preſented nearly an equal reſiſtance to the operation of the waters.
Though, in the tops of ſome hills which are flat, and pretty extenſive, we find hard ſtone immediately under the vegetable ſoil; yet it ſhould be remarked, that, in every example of this kind, what appears to be the ſummit of a hill is only a continuation of ſome more eleva⯑ted hill in the neighbourhood, the upper ſtrata of which conſiſt of ſoft, and the inferior ſtrata of hard ſtone; and the hard ſtone found on the top of the firſt hill is only a continuation of the under ſtrata of the higher hill.
Still, however, on the tops of hills which are not ſurmounted by higher grounds, the ſtone is moſtly of a ſoft and friable nature; and hard ſtone cannot be had without digging to a conſi⯑derable depth. It is between theſe layers of [463] hard ſtone only that marble is to be found; and it is variegated with different colours by metalic ſubſtances carried down by rain-water, and fil⯑trated through the ſtrata: And it is probable that, in every country which furniſhes ſtones, marble would be found, if pits were dug to a ſufficient depth: Quoto enim, ſays Pliny, loco non ſuum marmor invenitur? It is, in fact, a more common ſtone than is generally imagined, and diſſers from other ſtones only in the fineneſs of its grain, which renders it compact, and ſuſcep⯑tible of a fine and brilliant poliſh.
Both the perpendicular fiſſures, and the hori⯑zontal joints of quarries, are often filled, or en⯑cruſted, with concretions, which are ſometimes tranſparent, and of regular figures, as cryſtals, and ſometimes earthy and opaque. Water runs through the perpendicular fiſſures, and even penetrates the cloſe texture of the ſtone itſelf. Stones that are porous imbibe water ſo copiouſly, that froſt ſplits them in pieces. The rain-waters, by filtrating through different ſtrata, are impreg⯑nated with a great variety of ſubſtances. They firſt ſink through the perpendicular fiſſures; they then penetrate the ſtrata of ſtone, and depoſite in the horizontal joints, as well as in the per⯑pendicular fiſſures, ſuch matter as they collect in their courſe, and give riſe to different concre⯑tions, according to the nature of theſe ſubſtan⯑ces. For example, when the water filtrates through marle, clay, or ſoft ſtone, the matter [464] which it depoſites is nothing but a fine pure marle, and commonly appears in the perpendi⯑cular fiſſures under the form of a porous, ſoft, white, light ſubſtance, known among natura⯑liſts under the name of Lac Lunae, or Medulla Saxi.
When veins of water, charged with ſtoney matter, run along the horizontal joints of ſoft ſtone or chalk, this matter adheres to the ſurface of the ſtones, and forms a white, ſcaly, light, and ſpongy cruſt, which, from its reſemblance to the agaric, has been called mineral agaric. But, if the ſtrata through which the water penetrates be hard ſtone, the filter being cloſer, the water it lets paſs will be impregnated with a ſtoney matter more pure and homogeneous; and, conſe⯑quently, the particles being capable of a more compact and intimate union, will form concre⯑tions nearly of equal denſity with the ſtone it⯑ſelf, and ſomewhat tranſparent. In quarries of this kind, the ſurface of the ſtones are encruſted with undulated concretions, which entirely fill up the horizontal joints.
In grottos and cavities of rocks, which may be regarded as the baſins or common ſewers of the perpendicular fiſſures, the different directions of the veins of water give different forms to the concretions which reſult from them. Theſe forms are generally wreathed, or reſemble an in⯑verted cone, attached to the roof of the cavern; or, rather, they are white, hollow cylinders, com⯑poſed [465] of concentric coats. The impregnated waters ſometimes fall in drops upon the floor of the cavern, and form columns, and a thouſand whimſical figures, to which naturaliſts have given the different appellations of ſtalactites, ſtelegmites, oſteocollae, &c.
Laſtly, when the concreting juices iſſue im⯑mediately from marble, or very hard ſtone, the lapidific matter is rather diſſolved than ſuſpended in the water, and it forms a kind of columns with triangular points, which are tranſparent, and conſiſt of oblique coats. This ſubſtance is diſtinguiſhed by the name of ſpar or ſpalt. It is tranſparent and colourleſs, excepting when the ſtone or marble through which it filtrates con⯑tains metallic particles. This ſpar is of equal hardneſs with the ſtone itſelf, and it diſſolves in acids, and calcines with the ſame degree of heat. Hence it is evident, that ſpar is a true ſtone, and perfectly homogeneous. It may even be ſaid to be pure and elementary ſtone.
Moſt naturaliſts, however, conſider this as a diſtinct ſubſtance, exiſting independent of ſtone: It is the lapidiſic or cryſtalline juice, which, in their eſtimation, not only cements the particles of common ſtone, but even thoſe of flint. This juice, they alledge, daily augments the denſity of ſtones by reiterated filtrations, and at laſt converts them into flint: When concreted into ſpar, it perpetually receives freſh ſupplies of ſtill purer juice, which increaſes both its hardneſs [466] and its denſity, till it changes to the conſiſtence of glaſs, then to that of cryſtal, and at laſt it is converted into genuine diamond.
But, on this ſuppoſition, Why does the lapi⯑dific juice produce only ſtone in ſome provinces, and nothing but flint in others? It may be ſaid, that the one province is leſs antient than the other, and that the juice has not had time ſuffi⯑cient to complete its natural operations. But in this there is not the ſhadow of probability. Be⯑ſides, from whence does this juice proceed? If it gives riſe to ſtones and flints, from whence does it derive its own origin? It is obvious, that it has no exiſtence independent of thoſe ſubſtances which alone can impart to the water that pene⯑trates them a petrifying quality, which uniform⯑ly correſponds with their nature and peculiar properties. Thus, when it filtrates through ſtone, it produces ſpar; when it iſſues from flint, it forms cryſtal; and there are as many ſpecies of this juice as of bodies from which it proceeds. Experience confirms this account of the matter. The waters which filtrate through quarries of common ſtone form tender and calcinable con⯑cretions ſimilar to the ſtones themſelves. On the other hand, the waters which exſude from granite or from flint, produce concretions hard and vitrifiable, and they have all the other pro⯑perties of flint, as the former had all thoſe of ſtone. In the ſame manner, the waters that fil⯑trate through mineral and metallic ſubſtances, [467] give riſe to pyrites, marcaſites, and metallic grains.
It was formerly remarked, that all matter might be divided into the two great claſſes of Vitrifiable and Calcinable. Clay and flint, marle and ſtone, may be regarded as the two extremes of each claſs, the intervals between which are filled with an almoſt infinite variety of mixts, that have always one or other of theſe ſubſtances for their baſis.
The ſubſtances belonging to the firſt claſs can never acquire the properties of thoſe of the lat⯑ter. Stone, however antient, will for ever be equally removed from the nature of flint, as clay is from that of marle. No known agent can ever force them from the circle of combinations pe⯑culiar to their nature. Places which produce marble and ſtone will always continue to do ſo as infallibly as thoſe which produce only ſand⯑ſtone, flint, and granite, will never produce lime⯑ſtone or marble.
If we examine the order and diſtribution of the materials of a hill compoſed of vitrifiable ſubſtances, we will generally find, under the ve⯑getable ſoil, a ſtratum of clay, which is likewiſe a vitrifiable ſubſtance analogous to flint, and which, as already remarked, is only a decompo⯑ſition of vitrifiable ſand; or rather, we will find, under the ſoil, a ſtratum of vitrifiable ſand. This ſtratum of clay or of ſand correſponds with the bed of gravel in hills conſiſting of calcinable [468] matters. Below the ſtratum of clay or of ſand, we meet with ſome beds of free-ſtone, which ſeldom exceed half a foot in thickneſs, and they are divided into ſmall portions by perpendicular fiſſures. Under theſe are ſeveral ſtrata of the ſame matter, and likewiſe beds of vitrifiable ſand. In proportion as we deſcend, the free⯑ſtone is more denſe, and its thickneſs increaſes. Below theſe, we find what I call live-rock, or flint in large maſſes, a ſubſtance ſo hard as to re⯑ſiſt the file, and all kinds of acids, more power⯑fully than vitrifiable ſand or powder of glaſs, upon which aquafortis ſeems to have ſome effect. When ſtruck with another hard body, it throws out ſparks of fire, and exhales a penetrating ſul⯑phurcous vapour. This flinty ſubſtance is com⯑monly found along with beds of clay, of ſlate, of pit-coal, of vitrifiable ſand; and it correſponds to the ſtrata of hard-ſtone and marble, which ſerve as the baſes of hills that conſiſt of calci⯑nable matter.
The waters, in paſſing through the perpendi⯑cular fiſſures, and in penetrating the ſtrata of vitrifiable ſand, of free-ſtone, of clay, and of ſlate, are impregnated with the fineſt and moſt ho⯑mogeneous particles of theſe ſubſtances, and pro⯑duce various concretions, ſuch as tale, aſbeſtus, and other bodies which owe their exiſtence to diſtillation through vitriable matter.
Flint, notwithſtanding its hardneſs and denſi⯑ty, has, like marble and common ſtone, its exu⯑dations, [469] from which reſult ſtalactites of different ſpecies, varying in tranſparency, colour, and con⯑figuration, according to the nature of the flint that produces them, and to the different metallic or heterogeneous particles it contains. Rock⯑cryſtal, all the precious ſtones, and even the diamond itſelf, may be regarded as ſtalactites of this kind. The flints in ſmall maſſes, the ſtrata or coats of which are generally concentric, are only ſtalactites, or paraſitical ſtones, from the flints in large maſſes; and moſt of the fine opaque ſtones are nothing but ſpecies of flint. The ſubſtances produced by the vitrifiable claſs of bodies are not, as we have ſeen, ſo various as the concretions formed by thoſe of the calcinable. Moſt of the concretions formed by flint are hard and precious ſtones; but thoſe produced by cal⯑careous ſtones are friable, and of no value.
Perpendicular fiſſures are found in flint-rocks as well as in ſtone; they are even frequently larger in flint, which proves this ſubſtance to be drier than ſtone. Both the hill conſiſting of calcinable, and that compoſed of vitrifiable mat⯑ter, have clay or vitrifiable ſand for their baſes, which are the moſt commonly diffuſed matters of the globe, and which I regard as the lighteſt, being the ſcoriae of the vitrified matter that con⯑ſtitutes the interior parts of the earth. Thus all mountains as well as plains are founded either on clay or ſand. We have ſeen, for example, in the pits of Amſterdam, and in that of Marly⯑la-ville, [470] that vitrifiable ſand was always the deepeſt ſtratum.
It may be obſerved, in moſt bare rocks, that the walls of perpendicular fiſſures, whether they be narrow or wide, correſpond as exactly with each other as ſplit pieces of wood. In the large quarries of Arabia, which conſiſt moſtly of gra⯑nite, the perpendicular fiſſures are frequent; and, though ſome of them are 20 or 30 yards wide, the ſides correſpond exactly, and leave a deep cavity between them*. It is likewiſe common to find, in perpendicular fiſſures, ſhells divided into two pieces, each piece remaining attached to the oppoſite ſides of the fiſſure; which proves, that theſe ſhells were depoſited in the ſolid ſtratum before it was ſplit†.
In ſome quarries mentioned by Mr Shaw, the perpendicular fiſſures are exceedingly large; and for this reaſon, perhaps, it is, that they are leſs numerous. In quarries of granite and flint in large maſſes, blocks of ſtone may be raiſed, as the obeliſks and columns at Rome, of 60, 80, 100, and 150 feet long, without the leaſ inter⯑ruption. It appears, that theſe vaſt blocks have been raiſed from the ſame quarry, and, like ſome ſpecies of free-ſtone, that they may be had of any given thickneſs. In other ſubſtances, the perpendicular fiſſures are very narrow, as in clay, in marle, and in chalk; and they are wider in [471] marble and hard ſtone. Some are imperceptible, becauſe they have been filled with a matter near⯑ly ſimilar to that of the ſtone itſelf; but ſtill they interrupt the continuity of the ſtones, and are called hairs by the workmen. I have often remarked, that theſe hairs in marble and ſtone differed from perpendicular fiſſures only in the ſeparation of parts not being complete. Theſe ſpecies of fiſſures are filled with a tranſparent matter, which is a true ſpar. In quarries of free-ſtone, the fiſſures are numerous, and conſi⯑derably large, becauſe rocks of this kind have often a leſs ſolid baſe, than that which ſupports marble or lime-ſtone, the former generally reſt⯑ing upon a fine ſand, and the latter upon clay. In many places, free-ſtone is not to be found in large maſſes; and in moſt quarries, where this ſtone is good, the blocks lie irregularly upon one another, in the form of cubes or parallelopipeds, as in the hills of Fountainbleau, which appear, at a diſtance, like the ruins of old buildings. This irregular diſpoſition has been occaſioned by the ſandy foundation of theſe hills allowing the blocks to ſink and tumble upon each other, e⯑ſpecially where quarries have been formerly wrought, which has given riſe to a great variety of fiſſures and intervals between the different blocks: And it may be remarked, in all coun⯑tries abounding with ſand and free-ſtone, that there are many fragments of rocks and large ſtones in the middle of the plains and vallies; [472] and that, on the contrary, in countries abound⯑ing with marble and hard ſtone, theſe ſcattered fragments, which have rolled down from the hills, are exceedingly rare. This phaenomenon is owing to the different ſolidities of the baſes upon which theſe ſtones are ſupported, and to the extent of the banks of marble or lime-ſtone, which is always more conſiderable than that of free-ſtone.
IT has already been remarked, that rains, and the currents of water which they pro⯑duce, continually detach, from the ſummits and ſides of the mountains, earth, gravel, &c. and carry them down to the plains; and that the rivers tranſport part of them to the ſea. The plains, therefore, by freſh accumulations of mat⯑ter, are perpetually riſing higher; and the moun⯑tains, for the ſame reaſon, are conſtantly dimi⯑niſhing both in ſize and elevation. Of the ſinking of mountains, Joſeph Blancanus relates ſeveral facts which were publicly known in his time. The ſteeple of the village of Craich, in the county of Derby, was not viſible in 1572, [474] from a certain mountain, on account of a high⯑er mountain which intervened; but, 80 or 100 years afterwards, not only the ſteeple, but likewiſe part of the church, was viſible from the ſame ſtation. Dr Plot gives a ſimilar example of a mountain between Sibbertoft and Aſhby, in the county of Northampton. Sand, earth, gra⯑vel, and ſmall ſtones, are not only carried down by the rains, but they ſometimes undermine and drive before them large rocks, which conſide⯑rably diminiſh the height of mountains. In ge⯑nera, the rocks are pointed and perpendicular in proportion to the height and ſteepneſs of mountains. The rocks in high mountains are very ſtraight and naked. The large frag⯑ments that appear in the vallies have been de⯑tached by the operation of water and of froſts. Thus ſand and earth are not the only ſubſtances detached from mountains by the rains; they at⯑tack the hardeſt rocks, and carry down large frag⯑ments of them into the plains. At Nant-phrancon, in 1685, a part of a large rock, which was ſup⯑ported on a narrow baſe, being undermined by the waters, fell and ſplit into a number of frag⯑ments, the largeſt of which made deep trenches in the plain, croſſed a ſmall river, and ſtopped at the other ſide of it. To ſimilar accidents we muſt aſcribe the origin of all thoſe large ſtones which are found in vallies adjacent to moun⯑tains. This phaenomenon, as formerly remark⯑ed, is more common in countries where the [475] mountains are compoſed of ſand and free-ſtone, than in thoſe, the mountains of which conſiſt of clay and marble; becauſe ſand is a leſs ſolid baſis than clay.
To give an idea of the quantity of earth de⯑tached from mountains by the rains, we ſhall quote a paſſage on this ſubject from Dr Plot's natural hiſtory of Stafford. He remarks, that a great number of coins ſtruck in the reign of Edward IV. i.e. 200 years ago, were found bu⯑ried 18 feet below the ſurface: Hence, he con⯑cludes, the earth, which is marſhy where the coins were found, augments about a foot in ele⯑ven years, or an inch and a twelfth each year. A ſimilar obſervation may be made on trees bu⯑ried 17 feet below the ſurface, under which were found medals of Julius Caeſar. Thus, the ſoil of the plains in conſiderably augmented and ele⯑vated by the matters waſhed down from the mountains.
The ſand, gravel, and earth carried down from the mountains into the plains, form beds which ought not to be confounded with the original ſtrata of the globe. To the former belong the beds of tufa, of ſoft ſtone, and of ſand and gra⯑vel which have been rounded by the operation of water. To theſe may be added thoſe beds of ſtone which have been formed by a ſpecies of incruſtation, none of which derive their ori⯑gin from the motion or ſediments of the ſea. In theſe ſtrata of tufa and of ſoft imperfect ſtones, [476] we find a number of different vegetables, leaves of trees, land or river-ſhells, and ſmall terreſtri⯑al animals, but never ſea-ſhells, or other produc⯑tions of the ocean. This circumſtance, joined to their want of ſolidity, evidently proves, that theſe ſtrata have been ſuperinduced upon the dry ſurface of the earth, and that they are more re⯑cent than thoſe of marble and other ſtones which contain ſea-ſhells, and have been originally form⯑ed by the waters of the ſea. Tufa, and other new ſtones, appear to be hard and ſolid when firſt dug out of the earth; but they ſoon diſſolve after being expoſed to the operation of the wea⯑ther. Their ſubſtance is ſo different from that of true ſtone, that, when broken down in order to make ſand of them, they change into a kind of dirty earth. The ſtalactites, and other ſtony concretions which Mr Tournefort apprehended to be marbles which had vegetated, are not ge⯑nuine ſtones. We have already ſhown, that the formation of tufa is not antient; and that it is not entitled to be ranked with ſtones. Tufa is an im⯑perfect ſubſtance, differing from ſtone or earth, but deriving its origin from both by the inter⯑vention of rain-water, in the ſame manner as incruſtations are formed by the waters of certain ſprings. Thus, the ſtrata of theſe ſubſtances are not antient; nor have they, like the other ſpe⯑cies, been formed by ſediments from the waters of the ocean. The ſtrata of turf are alſo recent, and have been produced by ſucceſſive accumula⯑tions [477] of half corrupted trees and other vegetables. which owe their preſervation to a bituminous earth. No production of the ſea ever appears in any of theſe new ſtrata. But, on the contrary, we find in them many vegetables, the bones of land-animals, and land and river-ſhells. In the meadows near Aſhly, in the county of Nort⯑hampton, for example, they find, ſeveral feet be⯑low the ſurface, ſnail-ſhells, plants, herbs, and ſeveral ſpecies of river-ſhells, well preſerved; but not a ſingle ſea-ſhell appears*. All theſe new ſtrata have been formed by the waters on the ſurface changing their channels, and diffu⯑ſing themſelves on all ſides. Part of theſe wa⯑ters penetrate the earth, and run along the fiſ⯑ſures of rocks and ſtones. The reaſon why wa⯑ter is ſeldom found in high countries, or on the tops of hills, is, becauſe high grounds are gene⯑rally compoſed of ſtones and rocks. To find water, therefore, we muſt cut through the rocks till we arrive at clay or firm earth. But, when the thickneſs of the rock is great, as in high moun⯑tains where the rocks are often 1000 feet high, it is impoſſible to pierce them to their baſe; and conſequently it is impoſſible to find water in ſuch ſituations. There are even extenſive countries that afford no water, as in Arabia Petrea, which is a deſert where no rains fall, where the ſurface of the earth is covered with burning ſands, where there is hardly the appearance of any ſoil, and where nothing but a few ſickly plants are pro⯑duced. [478] In this miſerable country, wells are ſo rare, that travellers enumerate only five between Cairo and Mount Sinai, and the water they con⯑tain is bitter and ſaltiſh.
When the ſuperficial waters can find no out⯑lets or channels, they form marſhes and fens. The moſt celebrated fens in Europe are thoſe of Ruſſia at the ſource of the Tanais; and thoſe of Savolaxia and Enaſak in Finland: There are alſo conſiderable marſhes in Holland, Weſtphalia, and other countries. In Aſia are the marſhes of the Euphrates, of Tartary, and of the Palus Meotis. However, marſhes are leſs frequent in Aſia and Africa than in Europe. But the whole plains of America may be regarded as one continued marſh; which is a greater proof of the modern⯑neſs of this country, and of the ſcarcity of its inhabitants, than of their want of induſtry.
There are extenſive fens in England, particu⯑larly in Lincolnſhire, near the ſea, which has loſt a great quantity of land on one ſide, and gained as much on the other. In the antient ſoil many trees are found buried under the new earth which has been tranſported and depoſited by the water: The ſame phaenomenon is com⯑mon in the marſhes of Scotland. Near Bruges in Flanders, in digging to the depth of 40 or 50 feet, a vaſt number of trees were found, as cloſe to each other as they are in a foreſt. Their trunks, branches, and leaves were ſo well pre⯑ſerved, that their different ſpecies could be eaſily [479] diſtinguiſhed. About 500 years ago, the earth where theſe trees were found was covered with the ſea; and, before this time, we have neither record nor tradition of its exiſtence. It muſt, however, have been dry-land when the trees grew upon it. Thus the land that, in ſome re⯑mote period, was firm, and covered with wood, has been overwhelmed with the waters of the ſea, which, in the courſe of time, have depoſited 40 or 50 feet of earth upon the antient ſurface, and then retired. A number of ſubterraneous trees was likewiſe diſcovered at Youle in York⯑ſhire, near the river Humber. Some of them are ſo large as to be of uſe in building; and it is affirmed, that they are as durable as oak. The country-people cut them into long thin ſlices, and ſell them in the neighbouring villages, where the inhabitants employ them for lighting their pipes. All theſe trees appear to be broken; and the trunks are ſeparated from the roots, as if they had been thrown down by a hurricane or an inundation. The wood appears to be fir; it has the ſame ſmell when burnt, and makes the ſame kind of charcoal*. In the Iſle of Man, there is a marſh called Curragh, about ſix miles long and three broad, where ſubterraneous fir⯑trees are found; and, though 18 or 20 feet be⯑low the ſurface, they ſtand firm on their roots†. Theſe trees are common in the marſhes and bogs [480] of Somerſet, Cheſter, Lancaſhire, and Stafford. In ſome places there are ſubterraneous trees which have been cut, ſawed, and ſquared by the hands of men; and even axes, and other imple⯑ments, are often found near them. Between Birmingham and Bromley, in the county of Lincoln, there are hills of a fine light ſand, which is blown about by the winds, and tranſ⯑ported by the rains, leaving bare the roots of large firs, in which the impreſſions of the ax are ſtill exceedingly apparent. Theſe hills have un⯑queſtionably been formed, like downs, by ſuc⯑ceſſive accumulations of ſand tranſported by the motions of the ſea. Subterraneous trees are al⯑ſo frequent in the marſhes of Holland, Frizeland, and near Groningen, which abound in turfs.
Subterraneous trees are of different ſpecies, viz. firs, oaks, birch, beech, yew, hawthorn, wil⯑low, aſh, &c. In the fens of Lincoln, along the river Ouſe, and on Hatfield-chace in York⯑ſhire, theſe trees ſtand erect, as if they were growing in a foreſt. The oaks are extremely hard, and are uſed in building, where they are ſaid to laſt long, which I think improbable, as all the ſpecimens I have examined loſe their ſo⯑lidity, after being dried and expoſed to the air. The aſhes are tender, and ſoon fall into duſt. Some of theſe trees are evidently cut and ſawed with inſtruments; and the hatchets, which are ſometimes found along with them, reſemble the knives formerly uſed in ſacrifices. Beſides trees, [481] we alſo meet with vaſt quantities of filberds, a⯑corns, and fir-cones, in many other fens in Eng⯑land, Scotland, and Ireland, as well as in the marſhes of France, Switzerland, Savoy, and Italy*.
For four miles round the town of Modena, whenever the earth is dug to the depth of 63 feet, the workmen pierce about five feet more with a boring inſtrument, through which the water ruſhes up with ſuch impetuoſity, that it fills the wells to the top, almoſt inſtantaneouſly; the water in theſe wells continues perpetually, and is neither augmented nor diminiſhed by rains or drought. What is ſtill more remark⯑able in this ſpot, whenever the workmen dig to the depth of 14 feet, they find the rubbiſh and ruins of an antient city, paved ſtreets, houſes, and different pieces of Moſaic work. Below this, the earth is ſolid, and appears not to have been moved. Still lower, however, we find a moiſt ſoil mixed with vegetables; and, at the depth of 26 feet, entire trees, as filberds, with nuts upon them, and great quantities of branches and leaves. At 28 feet, there is a ſtratum of ſoft chalk, 11 feet thick, mixed with ſea-ſhells; and, after this, we ſtill meet with vegetables, leaves and branches of trees, till we arrive at the depth of 63 feet, where there is a ſtratum of ſand mixed with gravel and ſhells, ſimilar to thoſe that appear on the coaſts of Italy. Theſe [482] ſucceſſive ſtrata lie always in the ſame order, wherever pits have been dug; and ſometimes the boring inſtrument falls in with the trunks of large trees, which the workmen pierce with great labour: They likewiſe meet with bones of animals, pit-coal, flints, and pieces of iron. Ra⯑mazzini, who relates theſe facts, thinks, that the gulf [...] Venice formerly extended beyond Mo⯑der and that this land, in the progreſs of time, has been gradually formed by the rivers, aſſiſted, perhaps, by inundations of the ſea.
I will inſiſt no longer upon the varieties in the compoſition of new ſtrata. It is ſufficient to have ſh [...]wn that they have been produced by no other cauſe than the waters that run or are ſtagnant upon the ſurface, and that they are nei⯑ther ſo hard nor ſo ſolid as the antient ſtrata which were formed under the waters of the ocean.
FROM what we have remarked in Article 1. 7. 8. and 9. it is apparent, that the ter⯑reſtrial globe has undergone ſome great and ge⯑neral changes; and it is equally certain, from what has been delivered in the other articles, that the ſurface of the earth has ſuffered parti⯑cular alterations. Though we are not ſufficient⯑ly acquainted with the order or ſucceſſion of theſe particular changes, we know the principal cauſes which produced them. We can even di⯑ſtinguiſh their different effects; and, if we were able to collect all the facts which natural and ci⯑vil hiſtory afford concerning the revolutions [484] which have happened on the ſurface of the earth, our theory would unqueſtionably receive addi⯑tional ſupports, and would be rendered ſtill more ſatisfactory.
One of the principal cauſes of theſe revolu⯑tions is the motion of the ſea, which has conti⯑nued invariably the ſame in all ages; for, as the ſun, the moon, the earth, the waters, the air, &c. have exiſted from the moment of creation, the effects of the tides, of the motion of the ſea from eaſt to weſt, of the currents, and of the winds, muſt have been felt for an equal time: And, even ſuppoſing the axis of the globe to have formerly had a different inclination, and that the continents, as well as the ſeas, were diffe⯑rently diſpoſed, the motions of the ocean, and the cauſes and effects of the winds, would have remained unaltered. In whatever part of the globe the immenſe quantities of water which fill the ocean were collected, they would be ſubject to the ſame motions.
It was no ſooner ſuſpected that our continent might formerly have been the bottom of the ſea, than the fact became inconteſtible. The ſpoils of the ocean found in every place, the ho⯑rizontal poſition of the ſtrata, and the correſpon⯑ding angles of the hills and mountains, appear⯑ed to be convincing proofs; for, when we ex⯑amine the plains, the vallies, and the hills, it is apparent, that the ſurface of the earth has been figured by the waters. When we deſcend into [485] the bowels of the earth, it is equally evident, that thoſe ſtones which include ſea-ſhells, have been formed by ſediments depoſited by the wa⯑ters, ſince the ſea-ſhells themſelves are impreg⯑nated with the ſame matter that ſurrounds them. And, in fine, if we conſider the correſponding angles of the hills and mountains, we cannot he⯑ſitate in pronouncing, that they received their configuration and direction from currents of the ocean. It is true, that, ſince the earth was firſt left uncovered, the original figure of its ſurface has been gradually changing: The mountains have diminiſhed in height; the plains have been elevated; the angles of the hills have become more obtuſe; thoſe bodies which have been rol⯑led about by the rivers have received a roundiſh figure; new beds of tufa, of ſoft ſtone, of gra⯑vel, &c. have been formed. But every thing has remained eſſentially the ſame. The antient form is ſtill recogniſable; and I am perſuaded, that every man may be convinced, by his own eyes, of the truth of all that has been advanced on this ſubject; and that, whoever has attended to the proofs I have given, muſt be fully ſatis⯑fied, that the earth was formerly under the waters of the ocean, and that the ſurface which we now behold, received its configuration from the currents and movements of the ſea.
We formerly remarked, that the principal motion of the ſea is from eaſt to weſt. The ocean, accordingly, ſeems to have gained from [486] the eaſtern coaſts of both the Old and the New Continent, a ſpace of no leſs than 500 leagues. For the proofs, we muſt refer to Art. IX. and ſhall only here add, that the direction of all ſtraits which join two ſeas, is from eaſt to weſt. The ſtraits of Magellan, of Frobiſher, of Hud⯑ſon, of Ceylon, of the ſea of Corea, and of Kamtſchatka, lie all in this direction, and ap⯑pear to have been formed by the irruption of the waters, which, being forcibly puſhed from eaſt to weſt, have opened theſe paſſages, where the waters ſtill preſerve a ſtronger current in this direction than in any other; for, in all ſtraits of this kind, the tides are high and violent; but, in thoſe ſituated on the weſtern coaſts, as that of Gibraltar, of the Sound, &c. the motion of the tides is almoſt imperceptible.
The inequalities at the bottom of the ſea change the direction of the motion of the wa⯑ters. Theſe inequalities have originated from ſediments and matters tranſported by the tides, or by other movements in the water: The tides are the principal, and firſt, though not the only cauſe which produced theſe inequalities. The wind is another cauſe; though its action be⯑gins at the ſurface, it agitates the whole maſs to the greateſt depths, as appears from particular bodies which are detached from the bottom of the ſea, and thrown aſhore only during violent ſtorms.
[487] It has already been mentioned, that, between the Tropics, and even ſome degrees beyond them, an eaſt wind blows perpetually. This wind, which aſſiſts the general motion of the ſea from eaſt to weſt, is as antient as the tides; becauſe it is occaſioned by the rarefaction of the air produced by the heat of the ſun. There are two combined cauſes, therefore, the operation of which is greateſt in the equatorial regions: 1ſt, The tides, which are greateſt in the ſouthern latitudes; and, 2d, The eaſt winds, which con⯑ſtantly reign in theſe climates. Theſe two cauſes have concurred, from the firſt formation of the earth, in producing a motion in the waters from eaſt to weſt, and in agitating them more vio⯑lently in this region of the globe than in any other. It is for this reaſon that we find between the Tropics the greateſt inequalities upon the ſurface of the earth. That part of Africa which lies between theſe circles, is nothing but a group of different chains of mountains, extending, for the moſt part, from eaſt to weſt, as appears from the direction of the great rivers which tra⯑verſe this unknown region. The ſame obſer⯑vation holds with regard to the countries both of Aſia and America, which lie between the Tropics.
The general motion of the ſea from eaſt to weſt, combined with the tides, currents, and winds, produce a variety of effects, both on the bottom of the ocean, and on the coaſts. Vare⯑nius [488] thinks it extremely probable, that the gulfs and ſtraits have been formed by reiterated efforts of the ocean againſt the land; that the gulfs of Arabia, of Bengal, and of Cambaya, have been produced by irruptions of the waters, as well as the ſtraits between Sicily and Italy, between Ceylon and India, between Greece and Euboea, &c.; that the probability of ſuch irruptions, and of certain lands having been deſerted by the ſea, is ſtrengthened by the ſcarcity of iſlands in the middle of great ſeas, and by their never ap⯑pearing there in groups; that, in the immenſe ſpace occupied by the Pacific Ocean, there are only two or three ſmall iſlands near the centre of it; and that, in the vaſt Atlantic Ocean be⯑tween Africa and Braſil, we find only the ſmall iſlands of St Helena and Aſcenſion: But all iſlands lie near large continents, as thoſe of the Archipelago, which approach the continents both of Europe and Aſia; the Canaries are near Afri⯑ca; the Indian iſlands lie near the eaſtern part of the continent of Aſia; the Antilles lie off the coaſt of America; and the Azores alone lie at a conſiderable diſtance both from Africa and Ame⯑rica.
The popular tradition among the inhabitants of Ceylon, that their iſland had been ſeparated from the peninſula of India by an irruption of the ſea, is extremely probable. The great num⯑ber of rocks and ſhoals between the iſland of Sumatra and the continent demonſtrate their [489] former union. The Malabarians affirm, that the Maldiva iſlands made once a part of the con⯑tinent of India; and, in general, we may believe, without heſitation, that all the eaſtern iſlands have been ſeparated from continents by irruptions of the ocean*.
The iſland of Great Britain appears to have been formerly a part of the continent; and that England was once joined to France, the narrow⯑neſs of the ſtrait, and the ſameneſs of the ſtrata of ſtone and of earth on the oppoſite ſides, are a ſufficient indication. If we ſuppoſe, ſays Dr Wallis, that France was connected to England by an iſthmus between Calais and Dover, two tides would neceſſary ſtrike with violence againſt each ſide of it twice every twenty-four hours; and the operation of the ſea, both on the eaſt and weſt of this iſthmus, would, in the courſe of time, neceſſarily wear away ſuch a nar⯑row neck of land as we have ſuppoſed. The tides acting with violence not only againſt this iſthmus, but alſo againſt the coaſts of France and of England, muſt have carried away vaſt quantities of earth, ſand, and clay, from every part on which the waves exerted their fury. Their courſe, however, being interrupted by the iſthmus, they would not, as might be imagined, depoſite their ſediments upon its ſhores, but would tranſport and depoſite them on the great [490] plain which now forms the marſh of Romney, and is four miles broad and eight long; for no man, who has ever ſeen this plain, can poſſibly doubt of its having been formerly covered with the ſea, as, without the intervention of the dikes of Dimchurch, the ſpring-tides would ſtill over⯑flow a great part of it.
The German ſea would act in the ſame man⯑ner againſt this iſthmus and againſt the coaſts of England and Flanders, and would carry its ſedi⯑ments into Holland and Zeland, the ſoil of which was formerly under the waters, though it is now elevated 40 feet above them. On the Engliſh coaſt, the German ſea muſt have occupied that large valley which commences at Sandwich, runs by Canterbury, Chatham, Chilham, and terminates at Aſhford, a ſpace of more than 20 miles. Here the land is much more elevated than it was in antient times; for, at Chatham, the bones of an hyppopotamos have been found buried at the depth of 17 feet, and likewiſe anchors of ſhips, and ſea-ſhells.
Nothing is more apparent than that new lands are formed by the earth, ſand, clay, &c. tran⯑ſported and depoſited by the ſea: For, in the iſland of Orkney, which is adjacent to the marſhy coaſt of Romney, there was a flat ſpace of ground in continual danger of being overflowed by the river Rother; but this flat, in leſs than 60 years, has been conſiderably elevated by the acceſſion [491] of freſh matter brought in by every tide. This river has beſide deepened its channel ſo greatly, that its mouth, which, leſs than 50 years ago, was fordable by men, is now capable of receiving large veſſels.
In the ſame manner has the bank of ſand, which runs obliquely from the coaſt of Norfolk to that of Zeland, been formed. This bank is the place where the German and French ſeas encounter ſince the rupture of the iſthmus; and it is here where the waters depoſite the earth and ſand which they carry off from the coaſts. It is even not improbable but that this bank of ſand may, in a ſucceſſion of ages, give riſe to a new iſthmus*.
It is extremely probable, ſays Mr Ray, that the iſland of Great Britain was formerly joined to France: Whether it was disjoined by an earth⯑quake, by an irruption of the ocean, or by the operation of men, we know not. But the for⯑mer junction of Britain to the continent is ap⯑parent from the identity of the rocks and differ⯑ent ſtrata, at the ſame elevation, on the oppoſite coaſts; and from the ſimilar extent of the rocks on each ſide, being both about ſix miles. The narrowneſs of this ſtrait, which exceeds not 24 Engliſh miles, and its ſhallowneſs, when com⯑pared to the depth of the neighbouring ſea, ren⯑der it probable that England has been ſeparated from France by ſome accident. To theſe proofs [492] we might add, that wolves and bears formerly exiſted in this iſland: It is not probable that theſe animals could ſwim over, nor that ſuch deſtruc⯑tive creatures would be tranſported by men; for, in general, the noxious animals of the continent are found in all thoſe iſlands which are very near it, but never in thoſe that are remote. This fact was remarked by the Spaniards when they ar⯑rived in America*.
In the reign of Henry I. of England, a part of Flanders was overflowed by an irruption of the ſea. In 1446, more than 10,000 perſons were drowned by a ſimilar irruption in the ter⯑ritory of Dordrecht, and more than 100,000 round Dullart in Friſeland and in Zeland. In theſe two provinces, above 300 villages were overflowed. The tops of their towers and ſpires are ſtill viſible above the ſurface of the water.
From the coaſts of France, England, Holland, and Germany, the ſea has in many places re⯑treated. Hubert Thomas, in his deſcription of the country of Liege, aſſures us, that the walls of the city of Tongres were formerly ſurround⯑ed by the ſea, though it is now 35 leagues di⯑ſtant from it. This he proves by ſeveral ſatis⯑factory reaſons: Among others, he informs us, that, in his time, the iron rings to which ſhips were faſtened, ſtill remained in the walls. The fens of Lincoln, of the iſland of Ely, and the Crau of Provence in France, may be regarded as [493] lands abandoned by the ſea, which has likewiſe, ſince the year 1665, retired conſiderably from the mouth of the Rhone. At the mouth of the Arno in Italy, a large quantity of land has been gained from the ſea; and Ravenna, which was formerly a harbour, is no longer a ſea-port. The whole of Holland appears to be new land: The ſurface of the ground is nearly on a level with the ſea, although it has received daily ele⯑vations from the mud and earths tranſported by the Rhine, the Maeſe, &c.; for the ſoil of Holland was formerly, in many places, computed to be 50 feet below the bottom of the ſea.
It has been alledged, that, in the year 860, a furious tempeſt drove ſuch quantities of ſand up⯑on the coaſt, that the mouth of the Rhine near Catt was entirely blocked up; and that this river overflowed the whole country, overturned trees and houſes, and at laſt emptied itſelf into the channel of the Maeſe. In 1421, another inun⯑dation ſeparated the city of Dordrecht from the main land, overwhelmed 72 villages, and drown⯑ed 100,000 ſouls, beſide a vaſt number of cattle. The dike of Iſſel was broke down in 1638, by the ice-boards from the Rhine ſhutting up the paſſage of the water, which occaſioned in the dike an opening of ſeveral fathoms, and a great part of the province was laid under water before the breach could be repaired. The province of Zeland, in 1682, ſuffered a ſimilar inundation, which drowned more than 30 villages; and an [494] amazing number of men and cattle periſhed, ha⯑ving been ſurpriſed by the waters in the night⯑time. The loſs would have been ſtill greater, had not a ſouth-eaſt wind oppoſed the motion of the waves; for there was ſuch a ſwell in the ſea, that the water roſe 18 feet above the higheſt ground in the province*.
The harbour of Hithe, in the county of Kent, is entirely blocked up, notwithſtanding much labour and expence beſtowed, on different occa⯑ſions, to clear it. For ſeveral miles round, we find an aſtoniſhing quantity of ſhells and other ſea-bodies, which had been accumulated in an⯑tient times, and which are now covered with ſoil, and afford excellent paſturage. The ſea, on the other hand, often encroaches upon the land; as, for example, the lands of Goodwin, which formerly belonged to a nobleman of that name, are now converted into ſands, and are covered with the waters of the ocean. Thus the ſea gains upon ſome coaſts, and loſes upon others, according to their different ſituations and cir⯑cumſtances†.
Upon Mount Stella in Portugal, there is a lake, in which are found the wrecks of ſhips, though this mountain is 12 leagues diſtant from the ſea‡. Sabinius, in his commentary upon Ovid's Metamorphoſes, tells us, that, in the year [495] 1460, a ſhip, with its anchors, were found in one of the Alpine mines.
Theſe changes of ſea into land, and of land into ſea, are not peculiar to Europe. The other parts of the globe, if properly inveſtigated, would furniſh more ſtriking and numerous examples.
Calecut was formerly a celebrated city, and the capital of a kingdom of that name. It is now reduced to an inconſiderable town, ill-built, and almoſt deſerted. The ſea, which, for a cen⯑tury paſt, has gained greatly upon this coaſt, now covers moſt of the antient city. The veſ⯑ſels moor upon its ruins, and the port is chocked up with a number of rocks, upon which many veſſels have been wrecked*.
The province of Jucatan, a peninſula in the Gulf of Mexico, was formerly a part of the ſea. This neck of land ſtretches about 100 leagues in length, and is no where above 25 leagues broad. The air is hot and moiſt. The earth furniſhes plenty of water, though, in ſo large a country, there are neither rivers nor brooks; and, when pits are dug, ſuch multitudes of ſhells e⯑very where appear, as leave little room for doubt⯑ing that this whole tract was formerly a part of the ocean.
It is a tradition among the inhabitants of Ma⯑labar, that the Maldiva iſlands originally adhered to the continent of India, and that they were de⯑tached from it by the violence of the ocean.
[496] The number of theſe iſlands is ſo great, and they are ſeparated by ſuch narrow channels, that the bow-ſprits of veſſels drive off, in paſſing, leaves from the trees on each ſide; and, in ſome places, a vigorous man, by laying hold of a branch, may leap into another iſland* The cocoa⯑trees found at the bottom of the ſea, is a farther proof that the Maldiva's formerly belonged to the continent.
The iſland of Ceylon, thoſe of Rammanakoiel, and many other iſlands, it is believed, were alſo disjoined from the continent by the currents, which, in many places of the Indian ſea, are ex⯑tremely rapid† It is certain, however, that the ſea has encroached 30 or 40 leagues on the north-eaſt coaſt of Ceylon.
The ſea appears to have lately abandoned ma⯑ny of the promontories and iſlands of America. We have already remarked, that the territory of Jucatan is full of ſhells; the ſame phaenomenon takes place in the low grounds of Martinico and the other iſlands of the Antilles. The inhabi⯑tants diſtinguiſh the earth below the ſurface by the name of lime; becauſe they make lime of the ſhells, great banks of which lie immediately under the vegetable ſoil‡.
There are ſome lands which the ſea alternate⯑ly covers and leaves bare, as in ſeveral iſlands of [497] Norway, Scotland, the Maldiva's, the gulf of Cambaya, &c. The Baltic-ſea has gradually gained a great part of Pomerania; and it has covered and deſtroyed the celebrated port of Vi⯑neta. In the ſame manner, the Norwegian ſea has advanced into the continent, and formed ſeveral iſlands. The German ſea has incroach⯑ed upon Holland, near Catt, to ſuch a degree, that the ruins of an antient Roman citadel, which was formerly ſituated on the coaſt, lie now at a conſiderable diſtance in the ſea. The marſhy ground in the iſland of Ely, and the Crau of Provence, are, on the contrary, lands which the ſea has deſerted. The Downs have been formed by accumulations of ſand, earth, and ſhells, ſucceſſively driven upon the coaſts by winds blowing from the ſea. For example, on the weſt coaſts of France, Spain, and Africa, a violent weſt wind reigns, by which the waters are puſhed with violence againſt the ſhores; and downs, accordingly, are frequent on theſe coaſts. The eaſt winds, in the ſame manner, when they continue long, drive the waters ſo forcibly from the coaſts of Syria and Phoenicia, that large chains of rocks, which are covered during the weſt winds, are left dry. Beſides, downs are not compoſed of ſtones and marble, like the mountains which have been formed in the bot⯑tom of the ocean, becauſe they have not remain⯑ed long enough under the waters. That the wa⯑ters of the ſea poſſeſs a petrifying power, and that [498] the ſtones formed in the earth are very different from thoſe formed at the bottom of the ocean, is fully evinced in my diſcourſe on minerals.
Since finiſhing my theory of the earth, which was compoſed in the year 1744, I have peruſed M. Barrere's, diſſertation on the origin of figu⯑red ſtones. It gave me peculiar ſatisfaction to find that the ideas of this accompliſhed naturaliſt, concerning the formation of downs, and the duration of the ſea upon the ſurface of the earth which we inhabit, exactly correſponded with my own. Aiguis-mortes, which is now more than a league and a half from the ſea, was a port in the time of St Louis. Pſalmodi was an iſland in the 815; and it is now more than two leagues from the ſea. The ſame change has happened at Maguelone. The greateſt part of the vineyard of Agde was covered, about 40 years ago, with the waters of the ſea. In Spain, the ſea, within theſe few years, has retired con⯑ſiderably from Blanes, from Badalona, from the environs of the river Vobregat, from Cape Tor⯑toſa along the coaſt of Valencia, &c.
The ſea may form hills and mountains in different manners: 1. By tranſporting earth, ſlime, ſand, and ſhells from one place to another: 2. By depoſiting ſediments compoſed of ſmall particles detached from the bottom and from the coaſts: And, laſtly, hills and downs may be formed by ſand and other particles driven againſt the coaſts by particular winds; theſe are gradu⯑ally deſerted by the ſea, and become parts of the [499] dry land. The downs of Flanders and of Hol⯑land are of this kind; they conſiſt of ſmall cle⯑vations or hills, compoſed of ſand and ſhells, which have been blown from the ſea upon the coaſts. M. Barrere gives another example, which merits obſervation. 'The ſea,' he remarks, 'by its motion, detaches immenſe quantities of plants, ſand, ſhells and ſlime from its bottom, which are continually puſhed by the winds and the waves towards the coaſts. The perpetual re⯑petition of this operation muſt give riſe to gra⯑dual accumulations of new ſtrata, which ele⯑vate the earth, produce downs and hills, en⯑large the land, and conſine the ſea within nar⯑rower bounds.'
'It is apparent that new ſtrata of different materials muſt have been formed by the con⯑ſtant attrition of the waters, by the depoſition of ſediments, and by other cauſes, the operation of which has been co-eval with the exiſtence of the globe itſelf. Of this we have a remark⯑able proof in the different ſtrata of foſſil ſhells, and other ſea bodies found at Rouſſillon near the village of Naffiac, which is 7 or 8 leagues from the ſea. Theſe beds of ſhells, which in⯑cline at different angles from weſt to eaſt, are divided from each other by ſtrata of earth and ſand, ſometimes of a foot and a half, and ſome⯑times of two or three feet in thickneſs. In dry weather they ſeem as if ſprinkled over with ſalt, and form a chain of hillocks from 25 to [500] 30 fathoms high. A long chain of hillocks of ſuch a height could not be formed at once, but gradually, and by a long ſucceſſion of time. Effects ſomewhat ſimilar might have been pro⯑duced by an univerſal deluge. But, in this caſe, the different beds of foſſil ſhells, inſtead of preſerving a regular form, would have been blended together without any order.'
I entirely agree with the ſentiments of M. Barrere, excepting as to the formation of moun⯑tains, which cannot be ſolely aſcribed to thoſe cauſes which increaſe the land, and diminiſh the boundaries of the ocean. On the contrary, I think I can produce ſeveral convincing argu⯑ments to prove, that moſt of thoſe eminences, which appear on the ſurface of the earth, have actually received their original formation in the ſea itſelf: 1. Becauſe they have correſponding angles, which neceſſarily imply the cauſe we have aſſigned, namely, the motion of the cur⯑rents. 2. Becauſe downs and hills, which have originated from materials thrown upon the coaſts, are not, like common hills, compoſed of marble and hard ſtones. Beſides, the ſhells found in the former, are only in the foſſil ſtate; where⯑as thoſe in the latter are entirely petrified. Nei⯑ther is the poſition of the ſtrata equally hori⯑zontal in downs, as in the hills compoſed of marble and hard ſtone, but are more or leſs in⯑clined, as in the hills of Naffiac. On the contrary, in the hills and mountains formed by ſediments [501] under the waters of the ſea, the ſtrata are always parallel, and very often horizontal; and the ſhells and other matter of them are completely petrified. I deſpair not of being able to prove, that the marbles and other calcareous bodies, which are almoſt all compoſed of madrepores, aſtroites, and ſhells, have acquired their denſity and perfection at the bottom of the ocean. But the tufas, ſoft ſtones, incruſtations, ſtalactites, &c. which are likewiſe calcinable, and have been formed ſince the earth was left dry, can never acquire the degree of denſity and of petrifaction peculiar to marble and other hard ſtones.
The remarks of M. Saulmon, concerning the galets, which are found in many places, may be ſeen in the hiſtory of the French Academy, an⯑no 1707. Theſe galets are round, flat, finely poliſhed pieces of flint, thrown out by the ſea upon the coaſts. At Bayeux, and at Prutel, which is a league from the ſea, galets are found in digging pits and wells. The mountains of Bonneuil, of Broie, and of Queſnoy, which are 18 leagues diſtant from the ſea, are covered with galets. They are alſo found in the valley of Clermont in Beauvois. M. Saulmon farther informs us, that a hole, 16 feet in length, was pierced horizontally into the high beach of Treſ⯑port, which conſiſts of a ſoft earth; and that, in the ſpace of 30 years, it was entirely oblite⯑rated by the ſea. Suppoſing the ſea to encroach [502] uniformly upon this ſhore, it will gain half a league in 12000 years.
The motions of the ſea, therefore, muſt be regarded as the principal cauſe of all thoſe chan⯑ges which have already happened, and of thoſe which are daily produced upon the ſurface of the earth. But there are other cauſes, which, though leſs conſiderable, have ſome effect in changing the ſuperficial parts of this globe. The rivers, the brooks, the melting of ſnows, the tor⯑rents, the froſts, &c. have given riſe to many alterations. The rains have diminiſhed the height of the mountains; the rivers and brooks have elevated the plains, and dammed up the ſea at their mouths; the torrents and the melting of ſnows have ſcooped out deep ravines or fur⯑rows in the vallies and narrow paſſages between the mountains; the froſts have ſplit rocks, and detached them from their original ſtations: In⯑numerable examples of revolutions produced by all theſe cauſes might be given. Varenius tells us, that the rivers tranſport into the ſea vaſt quantities of earth, and depoſite them at greater or leſſer diſtances from the ſhore, in proportion to the rapidity of their currents. Theſe portions of earth fall to the bottom, and firſt form ſmall banks, which, by conſtant acceſſions, become ſhoals, and at laſt appear in the form of fertile and habitable iſlands. It is in this manner that the iſlands in the Nile, thoſe in the river St Lawrence, the iſland of Landa, ſituated near the [503] mouth of the river Coanza, on the coaſt of A⯑frica, the Norwegian iſlands, &c. have received their exiſtence*. To theſe may be added the iſland of Trong-ming in China, which has been gradually formed by matters brought down by the river Nankin, and depoſited near its mouth. This iſland is more than 20 leagues in length, and from 5 to 6 in breadth†.
The Po, the Trento, and other rivers of Italy, bring down ſuch quantities of earth into the lagunes of Venice, eſpecially in the time of inundations, that they muſt be gradually filled up. Many parts of them are already dry during the ebb tide; and there is in them no depth of water, excepting in the canals, which are ſup⯑ported at an immenſe expence.
Large ſand-banks are thrown up at the mouths of the Nile, of the Ganges, of the In⯑dus, of the Plata, and of many other rivers. La Loubere, in his voyage to Siam, informs us, that the banks of ſand and of earth augment daily, at the mouths of the great rivers of Aſia, to ſuch a degree that the navigation of them becomes every hour more difficult, and will ſoon be impracticable. The ſame obſervation applies to the great rivers of Europe, and eſpecially to the Wolga, which empties itſelf by more than 70 mouths into the Caſpian, and to the Danube, which runs into the Black Sea by ſeven mouths, &c.
[504] As it ſeldom rains in Egypt, the regular in⯑undations of the Nile proceed from the torrents which fall into it from Aethiopia. It brings down vaſt quantities of mud, which it depoſites annu⯑ally not only upon the ſoil of Egypt, but throws it to great diſtances into the ſea, where it is laying the foundations of a new country, which muſt ariſe, in the courſe of time, out of the boſom of the ocean; for, upon ſounding at the diſtance of 20 leagues from the coaſt, the mud of the Nile is found at the bottom of the ſea; and every year it receives freſh accumula⯑tions. The Lower Egypt, now called the Delta, was formerly a bay* Homer tells us, that the iſland of Pharos was a day and a night's voyage from Egypt; and now it is almoſt contiguous to the land. The ſoil of Egypt is not every where of an equal depth; it grows thinner the nearer we approach the ſea. Near the banks of the Nile, there are ſometimes more than 30 feet of good ſoil; but, at the end of the inun⯑dation, there remain not, perhaps, above 7 inches. All the cities of the Lower Egypt have been built upon artificial eminences† The town of Damietta, which is now ten miles from the ſea, was a part of the ocean in the year 1243. The town of Fooah, which, 300 years ago, was ſitu⯑ated at the mouth of the Canopic branch of the Nile, is now 7 miles diſtant from it. Within [505] 40 years paſt, the ſea has retired half a league from Roſetto, &c.*.
Many changes have alſo taken place at the mouths of the great rivers of America, and even in thoſe which have been but lately diſcovered. Char⯑levoix tells us, that, at the mouth of the Miſſi⯑ſippi, below New Orleans, the land runs out in⯑to a point, which appears not to be very antient; becauſe, wherever the earth is dug, plenty of water is found; and beſides, the many little iſlands which have recently appeared in all the mouths of this river, leave no room to doubt but that this point of land was formed in the ſame manner. It is certain, ſays he, that, when M. Salle ſailed down the Miſſiſippi to the ſea, the mouth of this river was conſiderably dif⯑ferent from what it now appears.
The nearer, he adds, we approach the ſea, this difference becomes the more conſpicuous. There is no water in moſt of the ſmall channels cut in the bar by the river. Theſe channels are greatly multiplied by the trees brought down by the current. A ſingle tree, with its branches and roots, when ſtopped in a ſhallow part of the river, will entangle a thouſand. I have ſeen, ſays he, 200 leagues from New Orleans, collec⯑tions of trees, any one of which would ſill all the wood-yards in Paris. Nothing can diſen⯑tangle them. The mud brought down by the river ſerves as a cement to them, and gradually [506] covers them. Every inundation leaves a new ſtratum; and, in a few years, plants and ſhrubs begin to grow. It is in this manner that moſt points of land and iſlands, which ſo often change the courſe of rivers, are originally produced.
All the revolutions, however, brought about by rivers, are very ſlow, and become not conſi⯑derable till after a long courſe of years. But thoſe which are occaſioned by inundations or earthquakes are ſudden, and almoſt inſtantaneous. According to the Timacus of Plato, we are aſ⯑ſured by the antient prieſts of Egypt, 600 years before the birth of Chriſt, that there exiſted an iſland beyond the Pillars of Hercules, called Atlantis, which was larger than both Aſia and Lybia taken together; and that this great iſland was ſunk under the waters of the ocean by a terrible earthquake. 'Traditur Athenienſis civi⯑tas reſtitiſſe olim innumeris hoſtium copiis quae, ex Atlantico mari profectae, propè cunctam Europam Aſiamque obſederunt; tunc enim fretum illud navigabile, habens in ore et quaſi veſtibulo ejus inſulam quam Herculis Columnas cognominant: Ferturque inſula illa Lybiâ ſi⯑mul et Aſiâ Major fuiſſe, per quam ad alias proximas inſulas patebat aditus, atque ex inſu⯑lis ad omnem continentem è conſpectu jacen⯑tem vero mari vicinam; ſed intrà os ipſum portus anguſto ſinu traditur, pelagus illud ve⯑rum mare, terra quoque illa verè erat conti⯑nens, &c. Poſt haec ingenti terrae motu ju⯑gique [507] diei unius et noctis illuvione factum eſt, ut terra dehiſcens omnes illos bellicoſos abſor⯑beret, et Atlantis inſula ſub vaſto gurgite mer⯑geretur.' Plato in Timaeo. This antient tra⯑dition is not devoid of probability. The lands ſwallowed up by the waters were, perhaps, thoſe which united Ireland to the Azores, and the Azores to the continent of America; for, in Ireland, there are the ſame foſſils, the ſame ſhells, and the ſame ſea-bodies, as appear in America, and ſome of them are found in no other part of Europe.
Two evidences are mentioned by Euſebius on the ſubject of deluges: The one is Melo, who affirms, that all the plains of Syria were former⯑ly laid under water: The other is Abidenus, who ſays, that, in the reign of King Siſithrus, there was a great deluge, which had been pre⯑dicted by Saturn. Plutarch De Solertia Anima⯑lium, Ovid, and other mythologiſts, deſcribe the deluge of Deucalion, which happened, they ſay, in Theſſaly, about 700 years after the univerſal deluge. It is alſo alledged, that there was a ſtill more antient deluge in Attica, during the time of Ogiges, about 230 years before that of Deucalion. In the year 1095, a deluge in Syria drowned a prodigious number of people*. In 1164, a deluge in Frieſland covered the whole environs of the coaſts, and drowned ſeveral thouſands of the inhabitants†. Another inun⯑dation, [508] in 1218, deſtroyed 100,000 men. Of inundations there are many other examples, as that which happened in England in the year 1604, &c.
Impetuous winds may be regarded as a third cauſe of changes on the ſurface of the globe. They not only give riſe to downs and hills along the ſea-coaſts, but they often arreſt rivers, make them regorge, and change their directions. They carry off cultivated lands, tear up trees, overturn houſes, and cover whole countries with ſand. Upon the coaſt of Britany, in France, we have an example of thoſe inundations of ſand: The hiſtory of the Academy, ann. 1722, deſcribes it in the following terms:
'In the environs of St Paul de Leon, in Lower Britany, there is a province on the ſea⯑coaſt, which, before the year 1666, was inha⯑bited; but is now totally deſerted, on account of the ſand, which has covered it to the depth of 20 feet, and which daily gains ground. Reckoning from the above period, the ſand has advanced about 6 leagues into the country; and it is now within half a league of St Paul, and that town muſt probably ſoon be deſerted, The tops of ſteeples, and of ſome chimnies, ſtill appear above this ocean of ſand. The inhabitants, however, have always had leiſure to quit their poſſeſſions in ſafety; p. 7.'
'This calamity is augmented by an eaſt, or a north wind, which elevate this fine ſand, and [509] carry it in ſuch quantities, and with ſuch ra⯑pidity, that M. Deſlandes, to whom the Aca⯑demy are indebted for the obſervation, when walking in this country during an eaſt wind, found himſelf obliged to ſhake his hat and his garments from time to time, on account of the great weight of ſand with which they were loaded. Beſides, when the wind is violent, it carries the ſand over a ſmall arm of the ſea as far as Roſcof, a port much frequented by fo⯑reign veſſels; and the ſand accumulates in the ſtreets of this villages to the height of two feet, which obliges the inhabitants to drive it off in waggons. It may be further remarked, that the ſand is mixed with ferruginous particles, which are recogniſable by the magnet.'
'The coaſt which furniſhes this ſand extends from St Paul to Plouefcat, a ſpace of more than four leagues; and it is nearly on a level with the ſea when the tide is full. It is ſituated in ſuch a manner that only the eaſt and north⯑eaſt winds can blow the ſand in upon the country. It is eaſy to conceive how ſand car⯑ried and accumulated into any place by the wind, may again be taken up by the ſame wind, and carried ſtill farther. Thus the ſand may continue advancing, and covering new lands, as long as the magazine from which it originally proceeds ſhall remain unexhauſted; for, if the fountain were once dried up, the ſand, by advancing, would diminiſh in [...], [510] and its deſtructive conſequences would gradu⯑ally decay. But it is not improbable that the ſea may long continue to ſupply freſh ſand, and keep this baneful magazine in a condition to do perpetual miſchief.'
'This diſaſter is not of an old date. Perhaps it was not till lately that the place was ſuffi⯑ciently ſtored to allow great quantities of ſand to be carried off; or, perhaps, it has but re⯑cently been left uncovered by the waters. This coaſt has undergone ſome change. At preſent, the ſea, at full tide, reaches half a league on this ſide of certain rocks, which it formerly never paſſed.'
'This miſerable province juſtifies what has been related, both by antient and by modern travellers, that whole cities, and even vaſt armies, have been buried by tempeſts of ſand in the deſarts of Arabia.'
Mr Shaw relates, that the ports of Laodicea, Tortoſa, Rowadſa, Tripoly, Tyre, Acra, and Jaffa, are blocked up with ſand tranſported by the high waves which riſe on that part of the coaſt, when the weſt winds blow with vio⯑lence*.
It is needleſs to give more examples of alte⯑rations on the ſurface of this globe. The fire, the air, and the waters, produce continual changes, which, in a ſucceſſion of ages, become conſiderable. The ſea and the land not only [511] change places from the effects of general and ſtated periodic laws, but a number of revolu⯑tions are brought about by particular and acci⯑dental cauſes, as earthquakes, inundations, ſink⯑ings of mountains, &c. Thus the ſurface of the earth, which we regard as the moſt permanent of all things, is ſubjected, like the reſt of nature, to perpetual viciſſitudes.
FROM the proofs delivered in Art. VII. and VIII. it appears to be an eſtabliſhed fact, that the whole ſurface of what is now dry land, was formerly buried under the waters of the ocean. It is equally clear, from Art. XII. that the flux and reflux, and other movements of the ocean, perpetually detach from the coaſts and from the bottom of the ſea, ſhells, and mat⯑ter of every ſpecies; and that theſe are depoſited in other places in the form of ſediments, and give riſe to the horizontal ſtrata which every where appear. In the IX. art. we have proved, that the inequalities on the ſurface of the globe have been occaſioned by the motion of the waters of the ſea; and that the mountains received their original formation from ſucceſſive accumulations of the ſediments above deſcribed. It is likewiſe evident, from Art. XIII. that the currents which firſt followed the direction of theſe inequalities, afterwards beſtowed on them their preſent fi⯑gure, that is, their alternate and correſponding angles. From Art. VIII. and XVIII. it appears, that moſt of the matters detached from the coaſts and from the bottom of the ſea were, when de⯑poſited in ſediments, in the form of a fine im⯑palpable [513] powder, which entirely filled the cavi⯑ties of ſhells, whether this powder was of the ſame nature, or only analogous to the matter of which the ſhells were compoſed. It is unde⯑niable, from Art. XVII. that the horizontal ſtra⯑ta, which have been formed by ſucceſſive accu⯑mulations of ſediments, and which at firſt were ſoft and ductile, acquired denſity and compact⯑neſs in proportion as they dried; and that the perpendicular fiſſures in the ſtrata derived their origin from the act of drying.
After peruſing Art. X. XI. XIV. XV. XVI. XVII. XVIII. and XIX. we muſt be convinced, that the ſurface of the earth has been disfigured by many revolutions and particular viciſſitudes, ariſing from the operation of the waters, and the effects of rains, froſt, rivers, winds, ſubterraneous fires, earthquakes, inundations, &c. and, conſe⯑quently, that the ſea has alternately changed places with the dry land, eſpecially in the firſt ages after the creation, when terreſtrial ſubſtan⯑ces were much ſofter than they are at preſent. It muſt, however, be acknowledged, that our judgment concerning the ſucceſſion of natural revolutions cannot fail to be very imperfect; that we are ſtill leſs competent judges of thoſe changes which owe their birth to fortuitous events; and, that the defect of hiſtoric records deprives us of the knowledge of particular facts. We deſiderate both time and experience. We never conſider, that, though our exiſtence here be extremely li⯑mited, [514] nature proceeds in her courſe. We are ambitious of condenſing into our momentary duration both the paſt and the future, without reflecting that human life is only a point of time, a ſingle fact in the hiſtory of the operations of the Almighty.
Take the following examples. The Count de Buffon having conceived the idea, that, by a certain management of animals at birth, the foramen ovale of the heart, inſtead of ſhutting ſoon af⯑ter reſpiration, might be kept open for life, inſtituted a ſet of experiments to determine the point. Through the whole of theſe experiments, the foramen ovale of the heart is tranſlated the navel; and the Count de Buffon is repreſented by our authors as drawing this ſtrange concluſion: 'This experiment I never car⯑ried further; but I ſaw enough to convince me, that reſpira⯑tion is leſs neceſſary to a new born, than to a grown animal; and that it might be poſſible, with proper precautions, to pre⯑vent, in this manner, the NAVEL from being cloſed, and thus produce excellent divers, and different kinds of amphibious ani⯑mals, which might live equally in air and water;' Tranſ. vol. 1. p. 15.
In vol. 1. p. 40. when enumerating the effects of caſtration, the tranſlators make Buffon exclaim: 'How great, for example, is the difference between an bull and a ox, between a ram and an ewe!'—Speaking of the foetus in utero, vol. 1. p. 165. we have the following paſſage: 'It poſſeſſes then very little oppor⯑tunity to exerciſe the ſenſe of ſeeing, which depends ſolely on the fineneſs of the ſkin, and which is common to all the body.' In vol. 1. p. 27. where mention is made of the uſe of the ſaliva of the mother, in promoting the digeſtion of the more ſolid kinds of nouriſhment taken by infants, Buffon is repreſented as ſaying. 'I conceive it [the ſaliva] to be highly uſeful, and excellently adapted to their conſideration.'
'Cows are alſo ſubject to drowſineſs [read abortion], if they are put to the plough, and not properly managed;' Tranſ. vol. 1. p. 454.
'This faculty of reproduction, which reſides in vegetables and minerals. [read animals];' Tranſ. vol. 4. p. 106.
The following paſſage is good ſenſe in the original.
'But, as we do not perceive theſe properties purely material, and as they make no impreſſion of themſelves, as they ſubſiſt in our participotion; and as, after death, or before life, they exiſt. and do not at all affect us, we cannot ſay they compoſe a part of our being; it is, therefore, the organization, the ſoul, and the life, which properly conſtitutes our exiſtence: Matter, conſidered in this light, is leſs the ſubject than the acceſſor: It is a foreign expanſion, the union of which is unknown, and the preſence hurt⯑ful to us, and this order of thoughts which conſtitutes our being, is, very probably, entirely independent;' Tranſ. vol. 4. p. 107.
More examples are unneceſſary. The attentive reader will diſcover ſimilar blunders, proceeding from ignorance of the ſub⯑jects, in almoſt every page. The tranſlators have alſo been un⯑lucky in their corrector to the the preſs; for the book is greatly de⯑formed by typographical errors, particularly in the Latin quota⯑tions:
E. g. in Tranſlation, vol. 4. p. 294. the following ſentence, as printed, is not to be underſtood: 'Atribus [A tribus] circiter annis teſtes arterio [arietis], adhuc calentes, ad aedes meas de⯑ferri caraveram [curaveram]; cum igitur materiam ed [ex] e⯑pididymibus eductum [eductam], ope microſcopii contemplarer, non ſine ingenti voluptate advertebum [advertebam] animalculae [animalcula] omnia, quotquot innatabant ſemini maſculino, eandem [eundam] natando curſum tenere, ita nimium [nimirum] ut quo itinore priora prenaterunt [praenatarent] eadem [eodem] poſteriora ſubſequerentur, adeo ut hiſce animalculis quaſis [qua⯑ſi] ſit ingenitum, quod oves ſactitare videmus, ſcilicet, ut pre⯑cedentium [praccedentium] veſtigiis que invernos [grex univerſus] incedat.' For ſimilar ſpecimens, ſee Tranſ. vol. 4. p. 192. 193. 221. 222. 282. 284. 290. 291. 293. 295. 310. 311. 312. 316. 320. 326. &c.