HUMAN invention has been exerciſed for ſeveral ages to account for the various irregularities of the earth. While thoſe philoſophers mentioned in the laſt chapter ſee nothing but beauty, ſymmetry, and order; there are others, who look upon the gloomy ſide of nature, enlarge on its defects, and ſeem to conſider the earth, on which they tread, as one ſcene of extenſive deſolation Buffon's ſecond diſcourſe. . Beneath its ſurface they obſerve minerals and waters confuſedly jumbled together; its different beds of earth irregularly lying upon each other; mountains riſing from places that once were level Senec. Quaeſt. lib. vi. cap. 21. ; and hills ſinking into vallies; whole regions ſwallowed by the ſea, and others again riſing out of its boſom: all theſe they ſuppoſe to be but a few of the changes that have been wrought in our globe; and they ſend out immagination to deſcribe it in its primaeval ſtate of beauty.

Of thoſe who have written theories deſcribing the manner of the original formation of the earth, or accounting for its preſent appearances, the moſt celebrated are Burnet, Whiſton, Woodward, and Buffon. As ſpeculation is endleſs, ſo it is not to be wondered that all theſe differ from each other, and give oppoſite accounts of the ſeveral changes, which they ſuppoſe our earth to have undergone. As the ſyſtems of each have had their admirers, it is, in ſome meaſure, incumbent upon the natural hiſtorian to be acquainted, at leaſt, with their out-lines; and, indeed, to know what others have even dreamed, in matters of ſcience, is very uſeful, as it may often prevent us from indulging ſimilar deluſions ourſelves, which we ſhould never have adopted, but becauſe we take them to be wholly our own. However, as entering into a detail of theſe theories, is rather furniſhing an hiſtory of opinions than things, I will endeavour to be as conciſe as I can.

The firſt who formed this amuſement of earth-making into ſyſtem was the celebrated Thomas Burnet, a man of polite learning and rapid immagination. His Sacred Theory, as he calls it, deſcribing the changes which the earth has undergone, or ſhall hereafter undergo, is well known for the warmth with which it is immagined, and the weakneſs with which it is reaſoned, for the elegance of its ſtyle, and the meanneſs of its philoſophy. The earth, ſays he, before the deluge, was very differently formed from what it is at preſent: it was at firſt a fluid maſs; a chaos compoſed of various ſubſtances, differing both in denſity and figure: thoſe which were moſt heavy ſunk to the center, and formed in the middle of our globe an hard ſolid body; thoſe of a lighter nature remained next; and the waters, which were lighter ſtill, ſwam upon its ſurface, and covered the earth on every ſide. The air, and all thoſe fluids which were lighter than water, floated upon this alſo; and in the ſame manner encompaſſed the globe; ſo that between the ſurrounding body of waters, and the circumambient air, there was formed a coat of oil, and other unctuous ſubſtances, lighter than water. However, as the air was ſtill extremely impure, and muſt have carried up with it many of thoſe earthly particles with which it once was intimately blended, it ſoon began to defecate, and to depoſe theſe particles upon the only ſurface already mentioned, which ſoon uniting together, the earth and oil formed that cruſt, which ſoon became an habitable ſurface, giving life to vegetation, and dwelling to animals.

This immaginary antideluvian abode was very different from what we ſee it at preſent. The earth was light and rich; and formed of a ſubſtance entirely adapted to the feeble ſtate of incipient vegetation: it was an uniform plain, every where covered with verdure; without mountains, without ſeas, or the ſmalleſt inequalities. It had no difference of ſeaſons, for its equator was in the plain of the ecliptic, or, in other words, it turned directly oppoſite to the ſun, ſo that it enjoyed one perpetual and luxuriant ſpring. However, this delightful face of nature did not long continue the ſame, for, after a time, it began to crack and open in fiſſures; a circumſtance which always ſucceeds when the ſun dries away the moiſture from rich or marſhy ſituations. The crimes of mankind had been for ſome time preparing to draw down the wrath of Heaven; and they, at length, induced the Deity to defer repairing theſe breaches in nature. Thus the chaſms of the earth every day became wider, and, at length, they penetrated to the great abyſs of waters; and the whole earth, in a manner, fell in. Then enſued a total diſorder in the uniform beauty of the firſt creation, the terrene ſurface of the globe being broken down: as it ſunk the waters guſhed out into its place; the deluge became univerſal; all mankind except eight perſons were puniſhed with deſtruction, and their poſterity condemned to toil upon the ruins of deſolated nature.

It only remains to mention the manner in which he relieves the earth from this univerſal wreck, which would ſeem to be as difficult as even its firſt formation. "Theſe great maſſes of earth falling into the abyſs, drew down with them vaſt quantities alſo of air; and by daſhing againſt each other, and breaking into ſmall parts by the repeated violence of the ſhock, they, at length, left between them large cavities filled with nothing but air. Theſe cavities, naturally offered a bed to receive the influent waters; and in proportion as they filled, the face of the earth became once more viſible. The higher parts of its broken ſurface, now become the tops of mountains, were the firſt that appeared; the plains ſoon after came forward, and, at length, the whole globe was delivered from the waters, except the places in the loweſt ſituations; ſo that the ocean and the ſeas are ſtill a part of the ancient abyſs that have not had a place to return. Iſlands and rocks are fragments of the earth's former cruſt; kingdoms and continents are larger maſſes of its broken ſubſtance; and all the inequalities that are to be found on the ſurface of the preſent earth, are owing to the accidental confuſion into which both earth and waters were then thrown.

The next theoriſt was Woodward, who, in his Eſſay towards a Natural Hiſtory of the Earth, which was only deſigned to precede a greater work, has endeavoured to give a more rational account of its appearances; and was, in fact, much better furniſhed for ſuch an undertaking than any of his predeceſſors, being one of the moſt aſſiduous naturaliſts of his time. His little book, therefore, contains many important facts, relative to natural hiſtory, although his ſyſtem may be weak and groundleſs.

He begins by aſſerting that all terrene ſubſtances are diſpoſed in beds of various natures, lying horizontally one over the other, ſomewhat like the coats of an onion; that they are replete with ſhells, and other productions of the ſea: theſe ſhells being found in the deepeſt cavities, and on the tops of the higheſt mountains. From theſe obſervations, which are warranted by experience, he proceeds to obſerve, that theſe ſhells and extraneous foſſils are not productions of the earth, but are all actual remains of thoſe animals which they are known to reſemble; that all the beds of the earth lie under each other, in the order of their ſpecific gravity; and that they are diſpoſed as if they had been left there by ſubſiding waters. All theſe aſſertions he affirms with much earneſtneſs, although daily experience contradicts him in ſome of them; particularly we find layers of ſtone often over the lighteſt ſoils, and the ſofteſt earth under the hardeſt bodies. However, having taken it for granted, that all the layers of the earth are found in the order of their ſpecific gravity, the lighteſt at the top, and the heavieſt next the centre, he conſecquently aſſerts, and it will not improbably follow, that all the ſubſtances of which the earth is compoſed, were once in an actual ſtate of diſſolution. This univerſal diſſolution he takes to have happened at the time of the flood. He ſuppoſes that at that time a body of water, which was then in the center of the earth, uniting with that which was found on the ſurface, ſo far ſeparated the terrene parts as to mix all together in one fluid maſs; the contents of which afterwards ſinking according to their reſpective gravities, produced the preſent appearances of the earth. Being aware, however, of an objection that foſſile ſubſtances are not found diſſolved, he exempts them from this univerſal diſſolution, and, for that purpoſe, endeavours to ſhew that the parts of animals have a ſtronger coheſion than thoſe of minerals; and that, while even the hardeſt rocks may be diſſolved, bones and ſhells may ſtill continue entire.

So much for Wooodward; but of all the ſyſtems which were publiſhed reſpecting the earth's formation, that of Whiſton was moſt applauded, and moſt oppoſed. Nor need we wonder; for being ſupported with all the parade of deep calculation, it awed the ignorant, and produced the approbation of ſuch as would be thought otherwiſe, as it implied a knowledge of abſtruſe learning, to be even thought capable of comprehending what the writer aimed at. In fact, it is not eaſy to diveſt it of its mathematical garb; but thoſe who have had leiſure, have found the reſult of our philoſopher's reaſoning to be thus. He ſuppoſes the earth to have been originally a comet; and he conſiders the hiſtory of the creation, as given us in ſcripture, to have its commencement juſt when it was taken by the hand of the Creator, to be more regularly placed as a planet in our ſolar ſyſtem. Before that time, he ſuppoſes it to have been a globe without beauty or proportion; a world in diſoſder; ſubject to all the viciſſitudes which comets endure; ſome of which have been found, at different times, a thouſand times hotter than melted iron; at others, a thouſand times colder than ice. Theſe alternations of heat and cold, continually melting and freezing the ſurface of the earth, he ſuppoſes to have produced, to a certain depth, a chaos entirely reſembling that deſcribed by the poets, ſurrounding the ſolid contents of the earth, which ſtill continued unchanged in the midſt, making a great burning globe of more than two thouſand leagues in diameter. This ſurrounding chaos, however, was far from being ſolid: he reſembles it to a denſe though fluid atmoſphere, compoſed of ſubſtances mingled, agitated, and ſhocked againſt each other; and in this diſorder he deſcribes the earth to have been juſt at the eve of creation.

But upon its orbit's being then changed, when it was more regularly wheeled round the ſun, every thing took its proper places; every part of the ſurrounding fluid then fell into a ſituation, in proportion as it was light or heavy. The middle, or central part, which always remained unchanged, ſtill continued ſo, retaining a part of that heat which it received in its primaeval approaches towards the ſun; which heat, he calculates, may continue for about ſix thouſand years. Next to this fell the heavier parts of the chaotic atmoſphere, which ſerve to ſuſtain the lighter: but as in deſcending they could not entirely be ſeparated from many watery parts, with which they were intimately mixed, they drew down a part of theſe alſo with them; and theſe could not mount again after the ſurface of the earth was conſolidated: they, therefore, ſurrounded the heavy firſt deſcending parts, in the ſame manner as theſe ſurround the central globe. Thus the entire body of the earth is compoſed moſt internally of a great burning globe: next which, is placed an heavy terrene ſubſtance, that encompaſſes it; round which alſo is circumfuſed a body of water. Upon this body of waters, the cruſt of earth on which we inhabit is placed: ſo that, according to him, the globe is compoſed of a number of coats, or ſhells, one within the other, all of different denſities. The body of the earth being thus formed, the air, which is the lighteſt ſubſtance of all, ſurrounded its ſurface; and the beams of the ſun darting through, produced that light which, we are told, firſt obeyed the Creator's command.

The whole oeconomy of the creation being thus adjuſted, it only remained to account for the riſings and depreſſions on the ſurface of the earth, with the other ſeeming irregularities of its preſent appearance. The hills and vallies are conſidered by him as formed by their preſſing upon the internal fluid, which ſuſtains the outward ſhell of earth, with greater or leſs weight: thoſe parts of the earth which are heavieſt, ſink into the ſubjacent fluid more deeply, and become vallies: thoſe that are lighteſt, riſe higher upon the earth's ſurface, and are called mountains.

Such was the face of nature before the deluge; the earth was then more fertile and populous than it is at preſent; the life of man and animals was extended to ten times its preſent duration; and all theſe advantages aroſe from the ſuperior heat of the central globe, which ever ſince has been cooling. As its heat was then in its full power, the genial principle was alſo much greater than at preſent; vegetation and animal encreaſe were carried on with more vigour; and all nature ſeemed teeming with the ſeeds of life. But theſe phyſical advantages were only productive of moral evil; the warmth which invigorated the body encreaſed the paſſions and appetites of the mind; and, as man became more powerful, he grew leſs innocent. It was found neceſſary to puniſh his depravity; and all living creatures, except the fiſhes, who living in a cold element were not ſubject to a ſimilitude of guilt, were overwhelmed by the deluge in univerſal deſtruction.

This deluge, which ſimple believers are willing to aſcribe to a miracle, philoſophers have long been deſirous to account for by natural cauſes: they have proved that the earth could never ſupply from any reſervoir towards its center, nor the atmoſphere by any diſcharge from above, ſuch a quantity of water as would cover the ſurface of the globe to a certain depth over the tops of our higheſt mountains. Where, therefore, was all this water to be found? Whiſton has found enough, and more than a ſufficiency, in the tail of a comet; for he ſeems to alot comets a very active part in the great operations of nature.

He calculates, with great ſeeming preciſion, the year, the month, and the day of the week on which this comet (which has paid the earth ſome viſits ſince, though at a kinder diſtance) involved our globe in its tail. The tail he ſuppoſed to be a vaporous fluid ſubſtance, exhaled from the body of the comet, by the extreme heat of the ſun, and encreaſing in proportion as it approached that great luminary. It was in this that our globe was involved at the time of the deluge; and, as the earth ſtill acted by its natural attraction, it drew to itſelf all the watery vapours which were in the comet's tail; and the internal waters being alſo at the ſame time let looſe, in a very ſhort ſpace the tops of the higheſt mountains were laid under the deep.

The puniſhment of the deluge being thus compleated, and all the guilty deſtroyed, the earth, which had been broken by the eruption of the internal waters, was alſo enlarged by the ſame; ſo that upon the comet's receſs, there was found room ſufficient in the internal abyſs for the receſs of the ſuperfluous waters; whither they all retired, and left the earth uncovered, but in ſome reſpects changed, particularly in its figure, which, from being round, was now become oblate. In this univerſal wreck of nature Noah ſurvived, by a variety of happy cauſes, to re-people the earth, and to give birth to a race of men ſlow in believing ill-imagined theories of the earth.

After ſo many theories of the earth, which had been publiſhed, applauded, anſwered, and forgotten, Mr. Buffon ventured to add one more to the number. This philoſopher was, in every reſpect, better qualified than any of his predeceſſors for ſuch an attempt, being furniſhed with more materials, having a brighter imagination to find new proofs, and a better ſtyle to cloath them in. However, if one ſo ill qualified, as I am, may judge, this ſeems the weakeſt part of his admirable work; and I could wiſh, that he had been content with giving us facts inſtead of ſyſtems; that, inſtead of being a reaſoner, he had contented himſelf with being merely an hiſtorian.

He begins his ſyſtem by making a diſtinction between the firſt part of it and the laſt; the one being founded only on conjecture, the other depending entirely upon actual obſervation. The latter part of his theory may, therefore, be true, though the former ſhould be found erroneous.

The planets, ſays he, and the earth, among the number, might have been formerly (he only offers this as conjecture) a part of the body of the ſun, and adherent to its ſubſtance. In this ſituation, a comet falling in upon that great body might have given it ſuch a ſhock, and ſo ſhaken its whole frame, that ſome of its particles might have been driven off like ſtreaming ſparkles from red hot iron; and each of theſe ſtreams of fire, ſmall as they were in compariſon of the ſun, might have been large enough to have made an earth as great, nay many times greater than ours. So that in this manner the planets, together with the globe which we inhabit, might have been driven off from the body of the ſun by an impulſive force: in this manner alſo they would continue to recede from it for ever, were they not drawn back by its ſuperior power of attraction; and thus, by the combination of the two motions, they are wheeled round in circles.

Being in this manner detached at a diſtance from the body of the ſun, the planets, from having been at firſt globes of liquid fire, gradually became cool. The earth alſo having been daſhed obliquely forward, received a rotatory motion upon its axis at the very inſtant of its formation, and this motion being greateſt at the equator, the parts there acting againſt the force of gravity, they muſt have ſwollen out, and given the earth an oblate or flatted figure.

As to its internal ſubſtance, our globe having once belonged to the ſun, it continues to be an uniform maſs of melted matter, very probably vitrified in its primaeval fuſion. But its ſurface is very differently compoſed. Having been in the beginning heated to a degree equal to, if not greater than what comets are found to ſuſtain; like them it had an atmoſphere of vapours floating round it, and which cooling by degrees, condenſed and ſubſided upon its ſurface. Theſe vapours formed, according to their different denſities, the earth, the water, and the air; the heavier parts falling firſt, and the lighter remaining ſtill ſuſpended.

Thus far our philoſopher is, at leaſt, as much a ſyſtem maker as Whiſton or Burnet; and, indeed, he fights his way with great perſeverance and ingenuity through a thouſand objections that naturally ariſe. Having, at laſt, got upon the earth, he ſuppoſes himſelf on firmer ground, and goes forward with greater ſecurity. Turning his attention to the preſent appearance of things upon this globe, he pronounces from the view that the whole earth was at firſt under water. This water he ſuppoſes to have been the lighter parts of its former evaporation, which, while the earthy particles ſunk downwards by their natural gravity, floated on the ſurface, and covered it for a conſiderable ſpace of time.

"The ſurface of the earth," ſays he Theorie de la Terre, vol. 1, p. 111. , "muſt have been in the beginning much leſs ſolid than it is at preſent; and, conſequently, the ſame cauſes, which at this day produce but very ſlight changes, muſt then, upon ſo complying a ſubſtance, have had very conſiderable effects. We have no reaſon to doubt but that it was then covered with the waters of the ſea; and that thoſe waters were above the tops of our higheſt mountains, ſince, even in ſuch elevated ſituations, we find ſhells and other marine productions in very great abundance. It appears alſo that the ſea continued for a conſiderable time upon the face of the earth: for as theſe layers of ſhells are found ſo very frequent at ſuch great depths, and in ſuch prodigious quantities, it ſeems impoſſible for theſe to have ſupported their numbers all alive at one time; ſo that they muſt have been brought there by ſucceſſive depoſitions. Theſe ſhells alſo are found in the bodies of the hardeſt rocks, where they could not have been depoſited, all at once, at the time of deluge, or at any ſuch inſtant revolution; ſince that would be to ſuppoſe, that all the rocks in which they are found, were, at that inſtant, in a ſtate of diſſolution; which would be abſurd to aſſert. The ſea, therefore, depoſited them whereſoever they are now to be found, and that by ſlow and ſucceſſive degrees.

It will appear, alſo, that the ſea covered the whole earth, from the appearance of its layers, which lying regularly one above the other, ſeem all to reſemble the ſediment formed at different times by the ocean. Hence, by the irregular force of its waves, and its currents driving the bottom into ſand-banks, mountains muſt have been gradually formed within this univerſal covering of waters; and theſe ſucceſſively raiſing their heads above its ſurface, muſt, in time, have formed the higheſt ridges of mountains upon land, together with continents, iſlands, and low grounds, all in their turns. This opinion will receive additional weight by conſidering, that in thoſe parts of the earth where the power of the ocean is greateſt, the inequalities on the ſurface of the earth are higheſt: the ocean's power is greateſt at the equator, where its winds and tides are moſt conſtant; and, in fact, the mountains at the equator are found to be higher than in any other part of the world. The ſea, therefore, has produced the principal changes in our earth: rivers, volcanoes, earthquakes, ſtorms, and rain, having made but ſlight alterations, and only ſuch as have affected the globe to very inconſiderable depths.

This is but a very ſlight ſketch of Mr. Buffon's Theory of the Earth; a theory which he has much more powerfully ſupported, than happily invented; and it would be needleſs to take up the reader's time from the purſuit of truth in the diſcuſſion of plauſibilities. In fact, a thouſand queſtions might be aſked this moſt ingenious philoſopher, which he would not find it eaſy to anſwer; but ſuch is the lot of humanity, that a ſingle Goth can in one day deſtroy the fabric which Caeſars were employed an age in erecting. In fact, we might aſk, how mountains, which are compoſed of the moſt compact and ponderous ſubſtances, ſhould be the firſt whoſe parts the ſea began to remove? We might aſk, how foſſil-wood is found deeper even than ſhells? which argues, that trees grew upon, the places he ſuppoſes once to have been covered with the ocean. But we hope this excellent man is better employed than to think of gratifying the petulance of incredulity, by anſwering endleſs objections.

HAVING, in ſome meaſure, got free from the regions of conjecture, let us now proceed to a deſcription of the earth as we find it by examination, and obſerve its internal compoſition, as far as it has been the ſubject of experience, or expoſed to human enquiry. Theſe enquiries, indeed, have been carried but to a very little depth below its ſurface, and even in that diſquiſition men have been conducted more by motives of avarice than of curioſity. The deepeſt mine, which is that at Cotteberg in Hungary Boyle, vol. iii. p. 240. , reaches not more than three thouſand feet deep; but what proportion does that bear to the depth of the terreſtrial globe, down to the centre, which is above four thouſand miles? All, therefore, that has been ſaid of the earth, to a deeper degree, is merely fabulous or conjectural: we may ſuppoſe with one, that it is a globe of glaſs Buffon. ; with another, a ſphere of heated iron Whiſton. ; with a third, a great maſs of waters Burnet. ; and with a fourth, one dreadful volcano Kircher. ; but let us, at the ſame time, ſhew our conſciouſneſs, that all theſe are but ſuppoſitions.

Upon examining the earth, where it has been opened to any depth, the firſt thing that occurs, is the different layers or beds of which it is compoſed: theſe all lying horizontally one over the other like the leaves of a book, and each of them compoſed of materials that encreaſe in weight in proportion as they lie deeper. This is, in general, the diſpoſition of the different materials where the earth ſeems to have remained unmoleſted; but this order is frequently inverted; and we cannot tell whether from its original formation, or from accidental cauſes. Of different ſubſtances, thus diſpoſed, the far greateſt part of our globe conſiſts, from its ſurface downwards to the greateſt depths we ever dig or mine Woodward, p. 9. .

The firſt layer that is moſt commonly found at the ſurface, is that light coat of blackiſh mold, which is called, by ſome, garden earth. With this the earth is every where inveſted, unleſs it be waſhed off by rains, or removed by ſome other external violence. This ſeems to have been formed from animal and vegetable bodies decaying, and thus turning into its ſubſtance. It alſo ſerves again as a ſtore-houſe, from whence animal and vegetable nature are renewed, and thus are all vital bleſſings continued with unceaſing circulation. This earth, however, is not to be ſuppoſed entirely pure, but is mixed up with much ſtony and gravelly matter from the layers lying immediately beneath it. It generally happens, that the ſoil is fertile in proportion to the quantity that this putrified mold bears to the gravelly mixture; and as the former predominates, ſo far is the vegetation upon it more luxuriant. It is this external covering that ſupplies man with all the true riches he enjoys. He may bring up gold and jewels from greater depths; but they are merely the toys of a capricious being, things upon which he has placed an imaginary value, and for which fools alone part with the more ſubſtantial bleſſings of life. It is this earth, ſays Pliny Plinii Naturalis Hiſtoria, lib. 2, cap. 63. , that, like a kind mother, receives us at our birth, and ſuſtains us when born. It is this alone, of all the elements around us, that is never found an enemy to man. The body of waters deluge him with rains, oppreſs him with hail, and drown him with inundations. The air ruſhes in ſtorms, prepares the tempeſt, or lights up the volcano; but the earth, gentle and indulgent, ever ſubſervient to the wants of man, ſpreads his walks with flowers, and his table with plenty; returns with intereſt every good committed to her care; and, though ſhe produces the poiſon, ſhe ſtill ſupplies the antidote; though conſtantly teized more to furniſh the luxuries of man than his neceſſities, yet, even to the laſt, ſhe continues her kind indulgence, and, when life is over, ſhe piouſly covers his remains in her boſom.

This external and fruitful layer which covers the earth, is, as was ſaid, in a ſtate of continual change. Vegetables, which are naturally fixed and rooted to the ſame place, receive their adventitious nouriſhment from the ſurrounding earth and water: animals, which change from place to place, are ſupported by theſe, or by each other. Both, however, having for a time enjoyed a life adapted to their nature, give back to the earth thoſe ſpoils, which they had borrowed for a very ſhort ſpace, yet ſtill to be quickened again into freſh exiſtence. But the depoſits they make are of very diſſimilar kinds, and the earth is very differently enriched by their continuance. Thoſe countries that have for a long time ſupported men and other animals, having been obſerved to become every day more barren, while, on the contrary, thoſe deſolate places, in which vegetables only are abundantly produced, are known to be poſſeſt of amazing fertility. Buffon, vol. i. 353. "In regions which are uninhabited," ſays Mr. Buffon, "where the foreſts are not cut down, and where animals do not feed upon the plants, the bed of vegetable earth is conſtantly encreaſing. In all woods, and even in thoſe which are often cut, there is a layer of earth of ſix or eight inches thick, which has been formed by the leaves, branches and bark, which fall and rot upon the ground. I have frequently obſerved on a Roman way that croſſes Burgundy for a long extent, that there is a bed of black earth, of more than a foot thick, gathered over the ſtony pavement, on which ſeveral trees, of a very conſiderable ſize, are ſupported. This I have found to be nothing elſe than an earth formed by decayed leaves and branches, which have been converted by time into a black ſoil. Now as vegetables draw much more of their nouriſhment from the air and water than they do from the earth, it muſt follow, that in rotting upon the ground, they muſt give more to the ſoil than they have taken from it. Hence, therefore, in woods kept a long time without cutting, the ſoil below encreaſes to a conſiderable depth; and ſuch we actually find the ſoil in thoſe American wilds where the foreſts have been undiſturbed for ages. But it is otherwiſe where men and animals have long ſubſiſted; for as they make a conſiderable conſumption of wood and plants, both for firing and other uſes, they take more from the earth than they return to it: it follows, therefore, that the bed of vegetable earth, in an inhabited country, muſt be always diminiſhing; and muſt, at length, reſemble the ſoil of Arabia Petrea, and other provinces of the Eaſt, which having been long inhabited, are now become plains of ſalt and ſand; the fixed ſalt always remaining while the other volatile parts have flown away."

If from this external ſurface we deſcend deeper, and view the earth cut perpendicularly downwards, either in the banks of great rivers, or ſteepy ſea-ſhores; or, going ſtill deeper, if we obſerve it in quarries or mines, we ſhall find its layers regularly diſpoſed in their proper order. We muſt not expect, however, to find them of the ſame kind or thickneſs in every place, as they differ in different ſoils and ſituations. Sometimes marle is ſeen to be over ſand, and ſometimes under it. The moſt common diſpoſition is, that under the firſt earth is found gravel or ſand, then clay or marle, then chalk or coal, marbles, oars, ſands, gravels, and thus an alternation of theſe ſubſtances, each growing more denſe as it ſinks deeper. The clay, for inſtance, found at the depth of an hundred feet, is uſually more heavy than that found not far from the ſurface. In a well which was dug at Amſterdam, to the depth of two hundred and thirty feet, the following ſubſtances were found in ſucceſſion Varenius, as quoted by Mr. Buffon, p. 358. : ſeven feet of vegetable earth, nine of turf, nine of ſoft clay, eight of ſand, four of earth, ten of clay, four of earth, ten of ſand, two of clay, four of white ſand, one of ſoft earth, fourteen of ſand, eight of clay mixed with ſand, four of ſea-ſand mixed with ſhells, then an hundred and two feet of ſoft clay, and then thirty-one feet of ſand.

In a well dug at Marly, to the depth of an hundred feet, Mr. Buffon gives us a ſtill more exact enumeration of its layers of earth. Thirteen of a reddiſh gravel, two of gravel mingled with a vitrifiable ſand, three of limon, two of marle, four of marly ſtone, five of marle in duſt mixed with vitrifiable ſand, ſix of very fine vitrifiable ſand, three of earthy marle, three of hard marle, one of gravel, one of eglantine, a ſtone of the hardneſs and grain of marble, one of gravelly marle, one of ſtony marle, one of a coarſer kind of ſtony marle, two of a coarſer kind ſtill, one of vitrifiable ſand mixed with foſſil ſhells, two of fine gravel, three of ſtony marle, one of coarſe powdered marle, one of ſtone, calcinable like marble, three of grey ſand, two of white ſand, one of red ſand ſtreaked with white, eight of grey ſand with ſhells, three of very fine ſand, three of gres, four of red ſand ſtreaked with white, three of white ſand, and fifteen of reddiſh vitrifiable ſand."

In this manner the earth is every where found in beds over beds; and, what is ſtill remarkable, each of them, as far as it extends, always maintains exactly the ſame thickneſs. It is found alſo, that, as we proceed to conſiderable depths, every layer grows thicker. Thus in the adduced inſtances we might have obſerved, that the laſt layer was fifteen feet thick, while moſt of the others were not above eight, and this might have gone much deeper, for aught we can tell, as before they got through it the workmen ceaſed digging.

Theſe layers are ſometimes very extenſive, and often are found to obtain over a ſpace of ſome leagues in circumference. But it muſt not be ſuppoſed that they are uniformly continued over the whole globe without any interruption: on the contrary, they are ever, at ſmall intervals, cracked through as it were by perpendicular fiſſures; the earth reſembling, in this reſpect, the muddy bottom of a pond, from whence the water has been dried off by the ſun, and thus gaping in ſeveral chinks, which deſcend in a direction perpendicular to its ſurface. Theſe fiſſures are many times found empty, but oftener cloſed up with adventitious ſubſtances, that the rain, or ſome other accidental cauſes, have conveyed to fill their cavities. Their openings are not leſs different than their contents, ſome being not above half an inch wide, ſome a foot, and ſome ſeveral hundred yards aſunder. Theſe laſt form thoſe dreadful chaſms that are to be found in the Alps, at the edge of which the traveller ſtands dreading to look down at the immeaſurable gulph below. Theſe amazing clefts are well known to ſuch as have paſt theſe mountains, where a chaſm frequently preſents itſelf ſeveral hundred feet deep, and as many over, at the edge of which the way lies. It often happens alſo, that the road leads along the bottom, and then the ſpectator obſerves on each ſide frightful precipices ſeveral hundred yards above him; the ſides of which tally ſo exactly with each other, that they evidently ſeem torn aſunder.

But theſe chaſms to be found in the Alps, are nothing to what Ovalle tells us are to be ſeen in the Andes. Theſe amazing mountains, in compariſon of which the former are but little hills, have their fiſſures in proportion to their greatneſs. In ſome places they are a mile wide, and deep in proportion; and there are ſome others, that running underground, in extent reſemble a province.

Of this kind alſo is that cavern called Elden-hole, in Derbyſhire; which, Dr. Plot tells us, was ſounded by a line of eight and twenty hundred feet, without finding the bottom, or meeting with water: and yet the mouth at the top is not above forty yards over Phil. Tranſ. vol. ii. p. 370. . This immeaſurable cavern runs perpendicularly downward; and the ſides of it ſeem totally ſo plainly as to ſhew that they once were united. Thoſe who come to viſit the place, generally procure ſtones to be thrown into its mouth; and theſe are heard for ſeveral minutes, falling and ſtriking againſt the ſides of the cavern, producing a ſound that reſembles diſtant thunder, dying away as the ſtone goes deeper.

Of this kind alſo is that dreadful cavern deſcribed by Aelian; his account of which the reader may not have met with Aeliani Var. Hiſt. lib. 16, cap. 16. . "In the country of the Arrian Indians, is to be ſeen an amazing chaſm, which is called, The Gulph of Pluto. The depth, and the receſſes of this horrid place, are as extenſive as they are unknown. Neither the natives, nor the curious who viſit it, are able to tell how it firſt was made, or to what depths it deſcends. The Indians continually drive thither great multitudes of animals, more than three thouſand at a time, of different kinds, ſheep, horſes and goats; and, with an abſurd ſuperſtition, force them into the cavity, from whence they never return. Their ſeveral ſounds, however, are heard as they deſcend; the bleating of ſheep, the lowing of oxen, and the neighing of horſes, iſſuing up to the mouth of the cavern. Nor do theſe ſounds ceaſe, as the place is continually furniſhed with a freſh ſupply."

There are many more of theſe dreadful perpendicular fiſſures in different parts of the earth; with accounts of which, Kircher, Gaffarellus, and others who have given hiſtories of the wonders of the ſubterranean world, abundantly ſupply us. The generality of readers, however, will conſider them with leſs aſtoniſhment, when they are informed of their being common all over the earth: that in every field, in every quarry, theſe perpendicular fiſſures are to be found; either ſtill gaping, or filled with matter that has accidentally cloſed their interſtices. The inattentive ſpectator neglects the enquiry, but their being common is partly the cauſe that excites the philoſopher's attention to them; the irregularities of nature he is often content to let paſs unexamined; but when a conſtant and a common appearance preſents itſelf, every return of the object is a freſh call to his curioſity; and the chink in the next quarry becomes as great a matter of wonder as the chaſm in Elden-hole. Philoſophers have long, therefore, endeavoured to find out the cauſe of theſe perpendicular fiſſures, which our own countrymen, Woodward and Ray, were the firſt that found to be ſo common and univerſal. Mr. Buffon ſuppoſes them to be cracks made by the ſun, in drying up the earth immediately after its emerſion from the deep. The heat of the ſun is very probably a principal cauſe; but it is not right to aſcribe to one only, what we find may be the reſult of many. Earthquakes, ſevere froſts, burſting waters, and ſtorms tearing up the roots of trees, have, in our own times, produced them: and to this variety of cauſes, we muſt, at preſent, be content to aſſign thoſe that have happened before we had opportunities for obſervation.

IN ſurveying the ſubterranean wonders of the globe, beſides thoſe fiſſures that deſcend perpendicularly downwards, we frequently find others that deſcend but a little way, and then ſpread themſelves often to a great extent below the ſurface. Many of theſe caverns, it muſt be confeſſed, may be the production of art and human induſtry; retreats made to protect the oppreſſed, or ſhelter the ſpoiler. The famous labyrinth of Candia, for inſtance, is ſuppoſed to be entirely the work of art. Mr. Tournefort aſſures us, that it bears the impreſſion of human induſtry, and that great pains have been beſtowed upon its formation. The ſtone-quarry of Maeſtricht is evidently made by labour: carts enter at its mouth, and load within, then return and diſcharge their freight into boats that lie on the brink of the river Maeſe. This quarry is ſo large, that forty thouſand people may take ſhelter in it: and it in general ſerves for this purpoſe, when armies march that way; becoming then an impregnable retreat to the people that live thereabout. Nothing can be more beautiful than this cavern, when lighted up with torches; for there are thouſands of ſquare pillars, in large level walks, about twenty feet high; and all wrought with much neatneſs and regularity. In this vaſt grotto there is very little rubbiſh; which ſhews both the goodneſs of the ſtone, and the carefulneſs of the workmen. To add to its beauty, there alſo are in various parts of it, little pools of water, for the convenience of the men and cattle. It is remarkable alſo, that no droppings are ſeen to fall from the roof, nor are the walks any way wet under foot, except in caſes of great rains, where the water gets in by the air ſhafts. The Salt mines in Poland are ſtill more ſpacious than theſe. Some of the catacombs, both in Egypt and Italy, are ſaid to be very extenſive. But no part of the world has a greater number of artificial caverns than Spain, which were made to ſerve as retreats to the Chriſtians, againſt the fury of the Moors, when the latter conquered that country. However, an account of the works of art, does not properly belong to a natural hiſtory. It will be enough to obſerve, that though caverns be found in every country, far the greateſt part of them have been faſhioned only by the hand of Nature. Their ſize is found beyond the power of man to have effected; and their forms but ill adapted to the conveniences of an human habitation. In ſome places, indeed, we find mankind ſtill make uſe of them as houſes; particularly in thoſe countries where the climate is very ſevere Phil. Tranſ. vol. ii. p. 368. ; but in general they are deſerted by every race of meaner animals, except the bat; theſe nocturnal ſolitary creatures are uſually the only inhabitants; and theſe only in ſuch whoſe deſcent is ſloping, or, at leaſt, not directly perpendicular.

There is ſcarce a country in the world without its natural caverns; and many new cries are diſcovered every day. Of thoſe in England, Oakey-hole, The Devil's-hole, and Penpark-hole, have been often deſcribed. The former, which lies on the ſouth ſide of Mendip-hills Ibid. , within a mile of the town of Wells, is much reſorted to by travellers. To conceive a juſt idea of this, we muſt imagine a precipice of more than an hundred yards high, on the ſide of a mountain which ſhelves away a mile above it. In this is an opening not very large, into which you enter, going along upon a rocky uneven pavement, ſometimes aſcending, and ſometimes deſcending. The roof of it, as you advance, grows higher; and, in ſome places, is fifty feet from the floor. In ſome places, however, it is ſo low that a man muſt ſtoop to paſs. It extends itſelf, in length, about two hundred yards; and from every part of the roof, and the floor, there are formed ſparry concretions of various figures, that by ſtrong imaginations have been likened to men, lion, and organs. At the fartheſt part of this cavern riſes a ſtream of water, well ſtored with fiſh, large enough to turn a mill, and which diſcharges itſelf near the entrance.

Penpark-hole, in Glouceſterſhire, is almoſt as remarkable as the former. Captain Sturmey deſcended into this by a rope, twenty-five fathoms perpendicular, and at the bottom found a very large vault in the ſhape of an horſe-ſhoe. The floors conſiſted of a kind of white ſtone enamelled with lead ore, and the pendent rocks were glazed with ſpar. Walking forward on this ſtony pavement, for ſome time, he came to a great river, twenty fathoms broad, and eight fathoms deep; and having been informed that it ebbed and flowed with the ſea, he remained in this gloomy abode for five hours, to make an exact obſervation. He did not find, however, any alteration whatſoever in its appearance. But his curioſity was ill requited; for it coſt this unfortunate gentleman his life: immediately after his return, he was ſeized with an unuſual and violent head-ach, which threw him into a fever, of which he died ſoon after.

But of all the ſubterraneous caverns now known, the grotto of Antiparos is the moſt remarkable, as well for its extent, as for the beauty of its ſparry incruſtations. This celebrated cavern was firſt diſcovered by one Magni, an Italian traveller, about an hundred years ago, at Antiparos, an inconſiderable iſland of the Archipelago Kircher Mund. ſub. 122. I have tranſlated a part of Kircher's deſcription, rather than Tournefort's, as the latter was written to ſupport an hypotheſis.. The account he gives of it is long and inflated, but upon the whole amuſing. "Having been informed," ſays he, "by the natives of Paros, that in the little iſland of Antiparos, which lies about two miles from the former, of a gigantic ſtatue that was to be ſeen at the mouth of a cavern in that place, it was reſolved that we (the French conſul and himſelf) ſhould pay it a viſit. In purſuance of this reſolution, after we had landed on the iſland, and walked about four, miles thro' the midſt of beautiful plains, and ſloping woodlands, we at length came to a little hill, on the ſide of which yawned a moſt horrid cavern, that with its gloom at firſt ſtruck us with terror, and almoſt repreſt curioſity. Recovering the firſt ſurprize, however, we entered boldly; and had not proceeded above twenty paces, when the ſuppoſed ſtatue of the giant preſented itſelf to our view. We quickly perceived, that what the ignorant natives had been terrified at as a giant, was nothing more than a ſparry concretion, formed by the water dropping from the roof of the cave, and by degrees hardening into a figure that their fears had formed into a monſter. Incited by this extraordinary appearance, we were induced to proceed ſtill farther, in queſt of new adventures in this ſubterranean abode. As we proceeded, new wonders offered themſelves; the ſpars, formed into trees and ſhrubs, preſented a kind of petrified grove; ſome white, ſome green; and all receding in due perſpective. They ſtruck us with the more amazement, as we knew them to be mere productions of Nature, who, hitherto in ſolitude, had, in her playful moments, dreſſed the ſcene, as if for her own amuſement.

"But we had as yet ſeen but a few of the wonders of the place; and we were introduced as yet only into the portico of this amazing temple. In one corner of this half illuminated receſs, there appeared an opening of about three feet wide, which ſeemed to lead to a place totally dark, and that one of the natives aſſured us contained nothing more than a reſervoir of water. Upon this we tried, by throwing down ſome ſtones, which rumbling along the ſides of the deſcent for ſome time, the ſound ſeemed at laſt quaſhed in a bed of water. In order, however, to be more certain, we ſent in a Levantine mariner, who, by the promiſe of a good reward, with a flambeaux in his hand, ventured into this narrow aperture. After continuing within it for about a quarter of an hour, he returned, carrying ſome beautiful pieces of white ſpar in his hand, which art could neither imitate nor equal. Upon being informed by him that the place was full of theſe beautiful incruſtations, I ventured in once more with him, for about fifty paces, anxiouſly and cautiouſly deſcending by a ſteep and dangerous way. Finding, however, that we came to a precipice which led into a ſpacious amphitheatre, if I may ſo call it, ſtill deeper than any other part, we returned, and being provided with a ladder, flambeaux, and other things to expedite our deſcent, our whole company, man by man, ventured into the ſame opening, and deſcending one after another, we at laſt ſaw ourſelves all together in the moſt magnificent part of the cavern.

"Our candles being now all lighted up, and the whole place completely illuminated, never could the eye be preſented with a more glittering, or a more magnificent ſcene. The roof all hung with ſolid iſicles, tranſparent as glaſs, yet ſolid as marble. The eye could ſcarce reach the lofty and noble cieling; the ſides were regularly formed with ſpars; and the whole preſented the idea of a magnificent theatre, illuminated with an immenſe profuſion of lights. The floor conſiſted of ſolid marble; and in ſeveral places, magnificent columns, thrones, altars, and other objects appeared, as if nature had deſigned to mock the curioſities of art. Our voices, upon ſpeaking or ſinging, were redoubled to an aſtoniſhing loudneſs; and upon the firing of a gun, the noiſe and reverberations were almoſt deafening. In the midſt of this grand amphitheatre roſe a concretion of about fifteen feet high, that, in ſome meaſure, reſembled an altar; from which, taking the hint, we cauſed maſs to be celebrated there. The beautiful columns that ſhot up round the altar, appeared like candleſticks; and many other natural objects repreſented the cuſtomary ornaments of this ſacrament.

"Below even this ſpacious grotto, there ſeemed another cavern; down which I ventured with my former mariner, and deſcended about fifty paces by means of a rope. I at laſt arrived at a ſmall ſpot of level ground, where the bottom appeared different from that of the amphitheatre, being compoſed of ſoft clay, yielding to the preſſure, and in which I thruſt a ſtick to about ſix feet deep. In this, however, as above, numbers of the moſt beautiful chryſtals were formed; one of which, particularly, reſembled a table. Upon our egreſs from this amazing cavern, we perceived a Greek inſcription upon a rock at the mouth, but ſo obliterated by time, that we could not read it. It ſeemed to import that one Antipater, in the time of Alexander, had come thither; but whether he penetrated into the depths of the cavern, he does not think fit to inform us."

Such is the account of this beautiful ſcene, as communicated in a letter to Kircher. We have another, and a more copious deſcription of it by Tournefort, which is in every body's hands; but I have given the above, both becauſe it was communicated by the firſt diſcoverer, and becauſe it is a ſimple narrative of facts, without any reaſoning upon them. According to Tournefort's account, indeed, we might conclude, from the rapid growth of the ſpars in this grotto, that it muſt every year be growing narrower, and that it muſt, in time, be choaked up with them entirely; but no ſuch thing has happened hitherto, and the grotto at this day continues as ſpacious as we ever knew it.

This is not the place for an enquiry into the ſeeming vegetation of thoſe ſtony ſubſtances with which this and almoſt every cavern are incruſted. It is enough to obſerve, in general, that they are formed by an accumulation of that little gritty matter which is carried thither by the waters, and which in time acquires the hardneſs of marble. What in this place more imports us to know is, how theſe amazing hollows in the earth came to be formed. And I think, in the three inſtances above-mentioned, it is pretty evident, that their excavation has been owing to waters. Theſe finding ſubterraneous paſſages under the earth, and by long degrees hollowing the beds in which they flowed, the ground above them has ſlipt down cloſer to their ſurface, leaving the upper layers of the earth or ſtone ſtill ſuſpended. The ground that ſinks upon the face of the waters forming the floor of the cavern; the ground, or rock that keeps ſuſpended, forming the roof: and, indeed, there are but few of theſe caverns found without water, either within them, or near enough to point out their formation.

THE caverns, which we have been deſcribing, generally carry us but a very little way below the ſurface of the earth. Two hundred feet, at the utmoſt, is as much as the loweſt of them is found to ſink. The perpendicular fiſſures run much deeper; but few perſons have been bold enough to venture down to their deepeſt receſſes: and ſome few who have tried, have been able to bring back no tidings of the place, for unfortunately they left their lives below. The excavations of art have conduced us much further into the bowels of the globe. Some mines in Hungary are known to be a thouſand yards perpendicularly downwards; and I have been informed, by good authority, of a coal mine in the north of England, an hundred yards deeper ſtill.

It is beſide our preſent purpoſe to enquire into the peculiar conſtruction and contrivance of theſe, which more properly belongs to the hiſtory of foſſils. It will be ſufficient to obſerve in this place, that as we deſcend into the mines, the various layers of earth are ſeen, as we have already deſcribed them; and in ſome of theſe are always found the metals or minerals, for which the mine has been dug. Thus frequently gold is found diſperſed and mixed with clay and gravel Ulloa, vol. ii. p. 470. ; ſometimes it is mingled with other metallic bodies, ſtones, or bitumens; and Ulloa. ibid. ſometimes united with that moſt obſtinate of all ſubſtances, platina, from which ſcarce any art can ſeparate it. Silver is ſometimes found quite pure Macquer's Chymiſtry, vol. i. p. 316. , ſometimes mixed with other ſubſtances and minerals. Copper is found in beds mixed with various ſubſtances, marbles, ſulphurs, and pyrites. Tin, the ore of which is heavier than that of any other metal, is generally found mixed with every kind of matter: Hill's Foſſils, p. 628. lead is alſo equally common; and iron we well know can be extracted from all the ſubſtances upon earth.

The variety of ſubſtances which are thus found in the bowels of the earth, in their native ſtate, have a very different appearance from what they are afterwards taught to aſſume by human induftry. The richeſt metals are very often leſs glittering and ſplendid than the moſt uſeleſs marcaſites, and the baſeſt ores are in general the moſt beautiful to the eye.

This variety of ſubſtances, which compoſe the internal parts of our globe, is productive of equal varieties, both above and below its ſurface. The combination of the different minerals with each other, the heats which ariſe from their mixture, the vapours they diffuſe, the fires which they generate, or the colds which they ſometimes produce, are all either noxious or ſalutary to man; ſo that in this great elabratory of nature, a thouſand benefits and calamities are forging, of which we are wholly unconſcious; and it is happy for us that we are ſo.

Boyle, vol. iii. p. 232. Upon our deſcent into mines of conſiderable depth, the cold ſeems to encreaſe from the mouth as we deſcend; but after paſſing very low down, we begin, by degrees, to come into a warmer air, which ſenſibly grows hotter as we go deeper, till, at laſt, the labourers can ſcarce bear any covering as they continue working.

This difference in the air was ſuppoſed by Boyle to proceed from magazines of fire that lay nearer the centre, and that diffuſed their heat to the adjacent regions. But we now know that it may be aſcribed to more obvious cauſes. In ſome mines, the compoſition of the earth all around is of ſuch a nature, that upon the admiſſion of water or air, it frequently becomes hot, and often burſts out into eruptions. Beſide this, as the external air cannot readily reach the bottom, or be renewed there, an obſervable heat is perceived below, without the neceſſity of recurring to the central heat for an explanation.

Hence, therefore, there are two principal cauſes of the warmth at the bottom of mine: the heat of the ſubſtances of which the ſides are compoſed; and the want of renovation in the air below. Any ſulphureous ſubſtance mixed with iron, produces a very great heat, by the admiſſion of water. If, for inſtance, a quantity of ſulphur be mixed with a proportionable ſhare of iron filings, and both kneaded together into a ſoft paſte, with water, they will ſoon grow hot, and at laſt produce a flame. This experiment, produced by art, is very commonly effected within the bowels of the earth by nature. Sulphurs and irons are intimately blended together, and want only the mixture of water of air to excite their heat; and this, when once raiſed, is communicated to all bodies that lie within the ſphere of their operation. Thoſe beautiful minerals, called marcaſites and pyrites, are often of this compoſition; and wherever they are found, either by imbibing the moiſture of the air, or having been by any means combined with water, they render the mine conſiderably hot Kircher Mund. Subt. vol. ii. p. 216. .

The want of freſh air, alſo, at theſe depths, is, as we have ſaid, another reaſon for their being found much hotter. Indeed, without the aſſiſtance of art, the bottom of moſt mines would, from this cauſe, be inſupportable. To remedy this inconvenience, the miners are often obliged to ſink, at ſome convenient diſtance from the mouth of the pit where they are at work, another pit, which joins the former below, and which, in Derbyſhire, is called an airſhaft. Through this the air circulates; and thus the workmen are enabled to breathe freely at the bottom of the place; which becomes, as Mr. Boyle affirms, very commodious for reſpiration; and alſo very temperate as to heat and cold Boyle, vol. iii. p. 238. . Mr. Locke, however, who has left us an account of the Mendip mines, ſeems to preſent a different picture. "The deſcent into theſe is exceeding difficult and dangerous; for they are not ſunk like wells, perpendicularly, but as the crannies of the rocks happen to run. The conſtant method is to ſwing down by a rope, placed under the arms, and clamber along, by applying both feet and hands to the ſides of the narrow paſſage. The air is conveyed into them through a little paſſage that runs along the ſides from the top, where they ſet up ſome turfs, on the lee-ſide of the hole, to catch and force it down. Theſe turfs being removed to the windy ſide, or laid over the mouth of the hole, the miners below preſently want breath, and faint; and if ſweet ſmelling flowers chance to be placed there, they immediately loſe their fragrancy, and ſtink like carrion." An air ſo very putrifying can never be very commodious for reſpiration.

Indeed, if we examine the complexion of moſt miners, we ſhall be very well able to form a judgment of the unwholſomneſs of the place where they are confined. Their pale and ſallow looks ſhew how much the air is damaged by paſſing through thoſe deep and winding ways, that are rendered humid by damps, or warmed with noxious exhalations. But although every mine is unwholſome, all are not equally ſo. Coal-mines are generally leſs noxious than thoſe of tin; tin than thoſe of copper; but of all, none are ſo dreadfully deſtructive as thoſe of quickſilver. At the mines near the village of Idra, nothing can adequately deſcribe the deplorable infirmities of ſuch as fill the hoſpital there: emaciated and crippled, every limb contracted or convulſed, and ſome in a manner tranſpiring quickſilver at every pore. There was one man, ſays Dr. Pope Phil. Tranſ. vol. ii. p. 578. , who was not in the mines above half a year, and yet whoſe body was ſo impregnated with this mineral, that putting a piece of braſs money in his mouth, or rubbing it between his fingers, it immediately became as white as if it had been waſhed over with quickſilver. In this manner all the workmen are killed, ſooner or later; firſt becoming paralytic, and then dying conſumptive: and all this they ſuſtain for the trifling reward of ſeven-pence a day.

But theſe metalic mines are not ſo noxious from their own vapours, as from thoſe of the ſubſtances with which the ores are uſually united, ſuch as arſenic, cinnabar, bitumen, or vitriol. From the fumes of theſe, variouſly combined, and kept encloſed, are produced thoſe various damps that put on ſo many dreadful forms, and are uſually ſo fatal. Sometimes thoſe noxious vapours are perceived by the delightful fragrance of their ſmell Ibid. p. 375. , ſomewhat reſembling the pea-bloſſom in bloom, from whence one kind of damp has its name. The miners are not deceived, however, by its flattering appearances; but as they thus have timely notice of its coming, they avoid it while it continues, which is generally during the whole ſummer ſeaſon. Another ſhews its approach by the burning of the candles, which ſeem to collect their flame into a globe of light, and thus gradually leſſen, till they are quite extinguiſhed. From this alſo, the miners frequently eſcape; however, ſuch as have the misfortune to be caught in it, either ſwoon away, and are ſuffocated, or ſlowly recover in exceſſive agonies. Here is alſo a third, called the fulminating damp, much more dangerous than either of the former, as it ſtrikes down all before it, like a flaſh of gunpowder, without giving any warning of its approach. But there is ſtill another, more deadly than all the reſt, which is found in thoſe places where the vapour has been long confined, and has been, by ſome accident, ſet free. The air ruſhing out from thence, always goes upon deadly errands; and ſcarce any eſcape to deſcribe the ſymptoms of its operations.

Some colliers in Scotland, working near an old mine that had been long cloſed up, happened inadvertently to open an hole into it, from the pit where they were then employed. By great good fortune, they at that time perceived their error, and inſtantly fled for their lives. The next day, however, they were reſolved to renew their work in the ſame pit, and eight of them ventured down, without any great apprehenſions; but they had ſcarce got to the bottom of the ſtairs that led to the pit, but coming within the vapour, they all inſtantly dropped down dead, as if they had been ſhot. Amongſt theſe unfortunate poor men, there was one whoſe wife was informed that he was ſtifled in the mine; and as he happened to be next the entrance, ſhe ſo far ventured down as to ſee where he lay. As ſhe approached the place, the ſight of her huſband inſpired her with a deſire to reſcue him, if poſſible, from that dreadful ſituation; though a little reflection might have ſhewn her it was then too late. But nothing could deter her; ſhe ventured forward, and had ſcarce touched him with her hand, when the damp prevailed, and the miſguided, but faithful creature, fell dead by his ſide.

Thus, the vapours found beneath the ſurface of the earth, are very various in their effects upon the conſtitution: and they are not leſs in their appearances. There are many kinds that ſeemingly are no way prejudicial to health, but in which the workmen breathe freely; and yet in theſe, if a lighted candle be introduced, they immediately take fire, and the whole cavern at once becomes one furnace of flame. In mines, therefore, ſubject to damps of this kind, they are obliged to have recourſe to a very peculiar contrivance to ſupply ſufficient light for their operations. This is by a great wheel; the circumference of which is beſet with flints, which ſtriking againſt ſteels placed for that purpoſe at the extremity, a ſtream of fire is produced, which affords light enough; and yet which does not ſet fire to the mineral vapour.

Of this kind are the vapours of the mines about Briſtol: on the contrary, in other mines, a ſingle ſpark ſtruck out from the colliſion of flint and ſteel, would ſet the whole ſhaft in a flame. In ſuch, therefore, every precaution is uſed to avoid a colliſion ; the workmen making uſe only of wooden inſtruments in digging; and being cautious before they enter the mine, to take out even the nails from their ſhoes. Whence this ſtrange difference ſhould ariſe, that the vapours of ſome mines catch fire with a ſpark, and others only with a flame, is a queſtion that we muſt be content to leave in obſcurity, till we know more of the nature both of mineral vapour and of fire, This only we may obſerve, that gunpowder will readily fire with a ſpark, but not with the flame of a candle: on the other hand, ſpirits of wine will flame with a candle, but not with a ſpark; but even here the cauſe of this difference, as yet, remains a ſecret.

As from this account of mines, it appears that the internal parts of the globe are filled with vapours of various kinds, it is not ſuprizing, that they ſhould at different times reach the ſurface, and there put on various appearances. In fact, much of the ſalubrity, and much of the unwholſomeneſs of climates and ſoils, is to be aſcribed to theſe vapours, which make their way from the bowels of the earth upwards, and refreſh or taint the air with their exhalations. Salt mines being naturally cold Phil. Tranſ. vol. ii. p. 523. , ſend forth a degree of coldneſs to the external air, to comfort and refreſh it: on the contrary, metallic mines are known, not only to warm it with their exhalations, but often to deſtroy all kinds of vegetation by their volatile corroſive fumes. In ſome mines denſe vapours are plainly perceived iſſuing from their mouths, and ſenſibly warm to the touch. In ſome places, neither ſnow nor ice will continue on the ground that covers a mine; and over others 〈1 page duplicate〉 〈1 page duplicate〉 the fields are found deſtitute of verdure Boyle, vol. iii. p. 238. . The inhabitants, alſo, are rendered dreadfully ſenſible of theſe ſubterraneous exhalations, being affected with ſuch a variety of evils proceeding entirely from this cauſe, that books have been profeſſedly written upon this claſs of diſorders.

Nor are theſe vapours which thus eſcape to the ſurface of the earth, entirely unconfined; for they are frequently, in a manner, circumſcribed to a ſpot: the grotto Del Cane, near Naples, is an inſtance of this; the noxious effects of which have made that cavern ſo very famous. This grotto, which has ſo much employed the attention of travellers, lies within four miles of Naples, and is ſituated near a large lake of clear and wholeſome water Kircher Mund. Subt. vol. i. p. 191. . Nothing can exceed the beauty of the landſcape which this lake affords; being ſurrounded with hills covered with foreſts of the moſt beautiful verdure, and the whole bearing a kind of amphitheatrical appearance. However, this region, beautiful as it appears, is almoſt entirely uninhabited; the few peaſants that neceſſity compels to reſide there, looking quite conſumptive and ghaſtly, from the poiſonous exhalations that riſe from the earth. The famous grotto lies on the ſide of an hill, near which place a peaſant reſides, who keeps a number of dogs for the purpoſe of ſhewing the experiment to the curious. Theſe poor animals always ſeem perfectly ſenſible of the approach of a ſtranger, and endeavour to get out of the way. However, their attempts being perceived, they are taken and brought to the grotto; the noxious effects of which they have ſo frequently experienced. Upon entering this place, which is a little cave, or hole rather, dug into the hill, about eight feet high and twelve feet long, the obſerver can ſee no viſible marks of its peſtilential vapour; only to about a foot from the bottom, the wall ſeems to be tinged with a colour reſembling that which is given by ſtagnant waters. When the dog, this poor philoſophical martyr, as ſome have called him, is held above this mark, he does not ſeem to feel the ſmalleſt inconvenience; but when his head is thruſt down lower, he ſtruggles to get free for a little; but in the ſpace of four or five minutes he ſeems to loſe all ſenſation, and is taken out ſeemingly without life. Being plunged in the neighbouring lake, he quickly recovers, and is permitted to run home ſeemingly without the ſmalleſt injury.

This vapour, which thus for a time ſuffocates, is of the humid kind, as it extinguiſhes a torch, and ſullies a looking-glaſs; but there are other vapours perfectly inflamable, and that only require the approach of a candle to ſet them blazing. Of this kind was the burning well at Broſely, which is now ſtopped up; the vapour of which, when a candle was brought within about a foot of the ſurface of the water, caught flame like ſpirits of wine, and continued blazing for ſeveral hours after. Of this kind, alſo, are the perpetual fires in the kingdom of Perſia. In that province, where the worſhippers of fire hold their chief myſteries, the whole ſurface of the earth, for ſome extent, ſeems impregnated with inflamable vapours. A reed ſtuck into the ground continues to burn like a flambeaux; an hole made beneath the ſurface of the earth, inſtantly becomes a furnace anſwering all the purpoſes of a culinary fire. There they make lime by merely burying the ſtones in the earth, and watch with veneration the appearances of a flame that has not been extinguiſhed for times immemorial. How different are men in various climates! This deluded people worſhip theſe vapours as a deity, which in other parts of the world are conſidered as one of the greateſt evils.

HAVING given the theory of volcanoes, we have in ſome meaſure given alſo that of earthquakes. They both ſeem to proceed from the ſame cauſe, only with this difference, that the fury of the volcano is ſpent in the eruption, that of an earthquake ſpreads wider and acts more fatally by being confined. The volcano only affrights a province, earthquakes have laid whole kingdoms in ruin.

Philoſophers Ariſtotle, Agricola, Buffon. have taken ſome pains to diſtinguiſh between the various kinds of earthquakes, ſuch as the tremulous, the pulſative, the perpendicular, and the inclined; but theſe are rather the diſtinctions of art than of nature, mere accidental differences ariſing from the ſituation of the country or of the cauſe. If, for inſtance, the confined fire acts directly under a province or a town, it will heave the earth perpendicularly upward, and produce a perpendicular earthquake. If it acts at a diſtance, it will raiſe that tract obliquely, and thus the inhabitants will perceive an inclined one.

Nor does it ſeem to me that there is much greater reaſon for Mr. Buffon's diſtinction of earthquakes. One kind of which he ſuppoſes Buffon, vol. ii. 328. to be produced by fire in the manner of volcanoes, and confined to but a very narrow circumference. The other kind he aſcribes to the ſtruggles of confined air, expanded by heat in the bowels of the earth, and endeavouring to get free. For how do theſe two cauſes differ? Fire is an agent of no power whatſoever without air. It is the air, which being at firſt compreſt, and then dilated in a cannon, that drives the ball with ſuch force. It is the air ſtruggling for vent in a volcano, that throws up its contents to ſuch vaſt heights. In ſhort, it is the air confined in the bowels of the earth, and acquiring elaſticity by heat, that produces all thoſe appearances which are generally aſcribed to the operation of fire. When, therefore, we are told that there are two cauſes of earthquakes, we only learn, that a greater or ſmaller quantity of heat produces thoſe terrible effects; for air is the only active operator in either.

Some philoſophers, however, have been willing to give the air as great a ſhare in producing theſe terrible efforts as they could; and magnifying its powers have called in but a very moderate degree of heat to put it in action. Although experience tells us that the earth is full of inflamable materials, and that fires are produced wherever we deſcend; although it tells us that thoſe countries, where there are volcanoes, are moſt ſubject to earthquakes, yet they ſtep out of the way, and ſo find a new ſolution. Theſe only allow but juſt heat enough to produce the moſt dreadful phoenomena, and backing their aſſertions with long calculations, give theory an air of demonſtration. Mr. Amontons Memoires de l' Accademie de Sciences, An. 1703. has been particularly ſparing of the internal heat in this reſpect; and has ſhewn, perhaps accurately enough, that a very moderate degree of heat may ſuffice to give the air amazing powers of expanſion.

It is amazing enough, however, to trace the progreſs of a philoſophical fancy let looſe in immaginary ſpeculations. They run thus: "A very moderate degree of heat may bring the air into a condition capable of producing earthquakes; for the air at the depth of forty-three thouſand five hundred and twenty-eight fathom below the ſurface of the earth, becomes almoſt as heavy as quick-ſilver. This, however, is but a very ſlight depth in compariſon of the diſtance to the center, and is ſcarce a ſeventieth part of the way. The air, therefore, at the center muſt be infinitely heavier than mercury, or any body that we know of. This granted, we ſhall take ſomething more, and ſay, that it is very probable there is nothing but air at the center. Now let us ſuppoſe this air heated, by ſome means, even to the degree of boiling water, as we have proved that the denſity of the air is here very great, its elaſticity muſt be in proportion: an heat, therefore, which at the ſurface of the earth would have produced but a ſlight expanſive force, muſt at the center produce one very extraordinary, and, in ſhort, be perfectly irreſiſtible. Hence this force may with great eaſe produce earthquakes; and if encreaſed it may convulſe the globe; it may (by only adding figures enough to the calculation) deſtroy the ſolar ſyſtem, and even the fixed ſtars themſelves." Theſe reveries generally produce nothing; for, as I have ever obſerved, encreaſed calculations, while they ſeem to tire the memory, give the reaſoning faculty perfect repoſe.

However, as earthquakes are the moſt formidable miniſters of nature, it is not to be wondered that a multitude of writers have been curiouſly employed in their conſideration. Woodward has aſcribed the cauſe to a ſtoppage of the waters below the earth's ſurface by ſome accident. Theſe being thus accumulated, and yet acted upon by fires, which he ſuppoſes ſtill deeper, both contribute to heave up the earth upon their boſom. This he thinks accounts for the lakes of water produced in an earthquake, as well as for the fires that ſometimes burſt from the earth's ſurface upon thoſe dreadful occaſions. There are others ſtill who have ſuppoſed that the earth may be itſelf the cauſe of its own convulſions. When, ſay they, the roots or baſis of ſome large tract is worn away by a fluid underneath, the earth ſinking therein, its weight occaſions a tremor of the adjacent parts, ſometimes producing a noiſe, and ſometimes an inundation of water. Not to tire the reader with an hiſtory of opinions inſtead of facts, ſome have aſcribed them to electricity, and ſome to the ſame cauſes that produce thunder.

It would be tedious, therefore, to give all the various opinions that have employed the ſpeculative upon this ſubject. The activity of the internal heat ſeems alone ſufficient to account for every appearance that attends theſe tremendous irregularities of nature. To conceive this diſtinctly, let us ſuppoſe at ſome vaſt diſtance under the earth, large quantities of inflamable matter, pyrites, bitumens, and marcaſites diſpoſed, and only waiting for the aſperſion of water, or the humidity of the air, to put their fires in motion: at laſt, this dreadful mixture arrives; waters find their way into thoſe depths, through the perpendicular fiſſures; or air inſinuates itſelf through the ſame minute apertures: ſtrait new appearances enſue: thoſe ſubſtances, which for ages before lay dormant, now conceive new apparent qualities; they grow hot, produce new air, and only want room for expanſion. However, the narrow apertures by which the air or water had at firſt admiſſion, are now cloſed up; yet as new air is continually generated, and as the heat every moment gives this air new elaſticity, it at length burſts, and dilates all round; and, in its ſtruggles to get free, throws all above it into ſimilar convulſions. Thus an earthquake is produced, more or leſs extenſive, according to the depth or the greatneſs of the cauſe.

But before we proceed with the cauſes, let us take a ſhort view of the appearances which have attended the moſt remarkable earthquakes. By theſe we ſhall ſee how far the theoriſt correſponds with the hiſtorian. The greateſt we find in antiquity, is that mentioned by Pliny Plin. lib. ii. cap. 86. , in which twelve cities in Aſia Minor were ſwallowed up in one night: he tells us alſo of another, near the lake Thraſymene, which was not perceived by the armies of the Carthaginians and Romans, that were then engaged near that lake, although it ſhook the greateſt part of Italy. In another place Ibid. lib. iii. cap. 85. he gives the following account of an earthquake of an extraordinary kind. "When Lucius Marcus, and Sextus Julius, were conſuls, there appeared a very ſtrange prodigy of the earth, (as I have read in the books of Aetruſcan diſcipline) which happened in the province of Mutina. Two mountains ſhocked againſt each other, approaching and retiring with the moſt dreadful noiſe. They, at the ſame time, and in the midſt of the day, appeared to caſt forth fire and ſmoke, while a vaſt number of Roman knights and travellers from the Aemilian way, ſtood and continued amazed ſpectators. Several towns were deſtroyed by this ſhock; and all the animals that were near them were killed." In the times of Trajan, the city of Antioch, and a great part of the adjacent country, was buried by an earthquake. About three hundred years after, in the times of Juſtinian, it was once more deſtroyed, together with forty thouſand inhabitants: and, after an interval of ſixty years, the ſame ill-fated city was a third time overturned, with the loſs of not leſs than ſixty thouſand ſouls. In the year 1182, moſt of the cities of Syria, and the kingdom of Jeruſalem, were deſtroyed by the ſame accident. In the year 1594, the Italian hiſtorians deſcribe an earthquake at Puteoli, which cauſed the ſea to retire two hundred yards from its former bed.

But one of thoſe moſt particularly deſcribed in hiſtory, is that of the year 1693; the damages of which were chiefly felt in Sicily, but its motion perceived in Germany, France, and England. It extended to a circumference of two thouſand ſix hundred leagues; chiefly affecting the ſea-coaſts, and great rivers; more perceivable alſo upon the mountains than in the valleys. Its motions were ſo rapid, that thoſe who lay at their length, were toſſed from ſide to ſide, as upon a rolling billow Phil. Tranſ. . The walls were daſhed from their foundations; and no leſs than fifty-four cities, with an incredible number of villages, were either deſtroyed or greatly damaged. The city of Catanea, in particular, was utterly overthrown. A traveller, who was on his way thither, at the diſtance of ſome miles, perceived a black cloud, like night, hanging over the place. The ſea, all of a ſudden, began to roar; Mount Aetna to ſend forth great ſpires of flame; and ſoon after a ſhock enſued, with a noiſe as if all the artillery in the world had been at once diſcharged. Our traveller, being obliged to alight inſtantly, felt himſelf raiſed a foot from the ground; and turning his eyes to the city, he with amazement ſaw nothing but a thick cloud of duſt in the air. The birds flew about aſtoniſhed; the ſun was darkened; the beaſts ran howling from the hills; and, although the ſhock did not continue above three minutes, yet near nineteen thouſand of the inhabitants of Sicily periſhed in the ruins. Catanea, to which city the deſcriber was travelling, ſeemed the principal ſcene of ruin; its place only was to be found; and not a footſtep of its former magnificence was to be ſeen remaining.

The earthquake which happened in Jamaica, in 1692, was very terrible, and its deſcription ſufficiently minute. "In two minutes time it deſtroyed the town of Portugal, and ſunk the houſes in a gulph forty fathoms deep. It was attended with an hollow rumbling noiſe, like that of thunder; and, in leſs than a minute, three parts of the houſes, and their inhabitants, were all ſunk quite under water. While they were thus ſwallowed up on one ſide of the ſtreet, on the other, the houſes were thrown into heaps; the ſand of the ſtreet riſing like the waves of the ſea, lifting up thoſe that ſtood upon it, and immediately overwhelming them in pits. All the wells diſcharged their waters with the moſt vehement agitation. The ſea felt an equal ſhare of turbulence, and, burſting over its mounds, deluged all that came in its way. The fiſſures of the earth were, in ſome places, ſo great, that one of the ſtreets appeared twice as broad as formerly. In many places, however, it opened and cloſed again, and continued this agitation for ſome time. Of theſe openings, two or three hundred might be ſeen at a time; in ſome whereof the people were ſwallowed up; in others, the earth cloſing, caught them by the middle, and thus cruſhed them inſtantly to death. Other openings, ſtill more dreadful than the reſt, ſwallowed up whole ſtreets; and others, more formidable ſtill, ſpouted up whole cataracts of water, drowning ſuch as the earthquake had ſpared. The whole was attended with the moſt noiſome ſtench; while the thundering of the diſtant falling mountains, the whole ſky overcaſt with a duſky gloom, and the cruſh of falling habitations, gave unſpeakable horror to the ſcene. After this dreadful calamity was over, the whole iſland ſeemed converted into a ſcene of deſolation; ſcarce a planter's houſe was left ſtanding; almoſt all were ſwallowed up; houſes, people, trees, ſhared one univerſal ruin; and, in their places appeared great pools of water, which, when dried up by the ſun, left only a plain of barren ſand, without any veſtige of former inhabitants. Moſt of the rivers, during the earthquake, were ſtopt up by the falling in of the mountains; and it was not till after ſome time that they made themſelves new channels. The mountains ſeemed particularly attacked by the force of the ſhock; and it was ſuppoſed that the principal ſeat of the concuſſion was among them. Thoſe who were ſaved, got on board ſhips in the harbour; where many remained above two months, the ſhocks continuing during that interval with more or leſs violence every day."

As this deſcription ſeems to exhibit all the appearances that uſually make up the catalogue of terrors belonging to an earthquake, I will ſuppreſs the detail of that which happened at Liſbon, in our own times, and which is too recent to require a deſcription. In fact, there are few particulars in the accounts of thoſe who were preſent at that ſcene of deſolation, that we have not more minutely and accurately tranſmitted to us by former writers, whoſe narratives I have for that reaſon preferred. I will, therefore, cloſe this deſcription of human calamities, with the account of the dreadful earthquake at Calabria, in 1638. It is related by the celebrated Father Kircher, as it happened while he was on his journey to viſit Mount Aetna, and the reſt of the wonders that lie towards the ſouth of Italy. I need ſcarce inform the reader that Kircher is conſidered, by ſcholars, as one of the greateſt prodigies of learning.

"Having hired a boat, in company with four more, two friars of the order of St. Francis, and two ſeculars, we launched, on the twenty-fourth of March, from the harbour of Meſſina, in Sicily, and arrived, the ſame day, at the promontory of Pelorus. Our deſtination was for the city of Euphaemia, in Calabria, where we had ſome buſineſs to tranſact, and where we deſigned to tarry for ſome time. However, Providence ſeemed willing to croſs our deſign; for we were obliged to continue for three days at Pelorus, upon account of the weather; and though we often put out to ſea, yet we were as often driven back. At length, however, wearied with the delay, we reſolved to proſecute our voyage; and, although the ſea ſeemed more than uſually agitated, yet we ventured forward. The gulph of Charybdis, which we approached, ſeemed whirled round in ſuch a manner as to form a vaſt hollow, verging to a point in the center. Proceeding onward, and turning my eyes to Aetna, I ſaw it caſt forth large volumes of ſmoke, of mountainous ſizes, which entirely covered the whole iſland, and blotted out the very ſhores from my view. This, together with the dreadful noiſe, and the ſulphureous ſtench, which was ſtrongly perceived, filled me with apprehenſions that ſome more dreadful calamity was impending. The ſea itſelf ſeemed to wear a very unuſual appearance; thoſe who have ſeen a lake in a violent ſhower of rain covered all over with bubbles, will conceive ſome idea of its agitations. My ſurprize was ſtill encreaſed by the calmneſs and ſerenity of the weather; not a breeze, not a cloud which might be ſuppoſed to put all Nature thus into motion. I therefore warned my companions that an earthquake was approaching; and, after ſome time, making for the ſhore with all poſſible diligence, we landed at Tropaea, happy and thankful for having eſcaped the threatening dangers of the ſea.

"But our triumphs at land were of ſhort duration; for we had ſcarce arrived at the Jeſuits College in that city, when our ears were ſtunned with an horrid ſound, reſembling that of an infinite number of chariots driven fiercely forward, the wheels rattling, and the thongs cracking. Soon after this, a moſt dreadful earthquake enſued; ſo that the whole tract upon which we ſtood, ſeemed to vibrate, as if we were in the ſcale of a balance that continued wavering. This motion, however, ſoon grew more violent; and being no longer able to keep my legs, I was thrown proſtrate upon the ground. In the mean time, the univerſal ruin round me, redoubled my amazement. The craſh of falling houſes, the tottering of towers, and the groans of the dying, all contributed to raiſe my terror and deſpair. On every ſide of me I ſaw nothing but a ſcene of ruin; and danger threatening wherever I ſhould fly. I commended myſelf to God as my laſt great refuge. At that hour, O how vain was every ſublunary happineſs! wealth, honour, empire, wiſdom, all mere uſeleſs ſounds, and as empty as the bubbles in the deep. Juſt ſtanding on the threſhold of eternity, nothing but God was my pleaſure; and the nearer I approached, I only loved him the more. After ſome time, however, finding that I remained unhurt, amidſt the general concuſſion, I reſolved to venture for ſafety, and running as faſt as I could, reached the ſhore, but almoſt terrified out of my reaſon. I did not ſearch long here till I found the boat in which I had landed, and my companions alſo, whoſe terrors were even greater than mine. Our meeting was not of that kind where every one is deſirous of telling his own happy eſcape; it was all ſilence, and a gloomy dread of impending terrors.

"Leaving this ſeat of deſolation, we proſecuted our voyage along the coaſts; and the next day came to Rochetta, where we landed, although the earth ſtill continued in violent agitations. But we were ſcarce arrived at our inn, when we were once more obliged to return to the boat; and, in about half an hour, we ſaw the greateſt part of the town, and the inn at which we had ſet up, daſhed to the ground, and burying all its inhabitants beneath its ruins.

"In this manner, proceeding onward in our little veſſel, finding no ſafety at land, and yet, from the ſmallneſs of our boat, having but a very dangerous continuance at ſea, we at length landed at Lopizium, a caſtle midway between Tropaea and Euphemia, the city to which, as I ſaid before, we were bound. Here, wherever I turned my eyes, nothing but ſcenes of ruin and horror appeared; towns and caſtles levelled to the ground; Strombalo, though at ſixty miles diſtance, belching forth flames in an unuſual manner, and with a noiſe which I could diſtinctly hear. But my attention was quickly turned from more remote to contiguous danger. The rumbling ſound of an approaching earthquake, which we by this time were grown acquainted with, alarmed us for the conſequences; it every moment ſeemed to grow louder, and to approach more near. The place on which we ſtood now began to ſhake moſt dreadfully, ſo that being unable to ſtand, my companions and I caught hold of whatever ſhrub grew next us, and ſupported ourſelves in that manner.

"After ſome time, this violent paroxyſm ceaſing, we again ſtood up, in order to proſecute our voyage to Euphaemia, that lay within ſight. In the mean time, while we were preparing for this purpoſe, I turned my eyes towards the city, but could ſee only a frightful dark cloud, that ſeemed to reſt upon the place. This the more ſurprized us, as the weather was ſo very ſerene. We waited, therefore, till the cloud was paſt away: then turning to look for the city, it was totally ſunk. Wonderful to tell! nothing but a diſmal and putrid lake was ſeen where it ſtood. We looked about to find ſome one that could tell us of its ſad cataſtrophe, but could ſee none. All was become a melancholy ſolitude; a ſcene of hideous deſolation. Thus proceeding penſively along, in queſt of ſome human being that could give us ſome little information, we at length ſaw a boy ſitting by the ſhore, and appearing ſtupified with terror. Of him, therefore, we enquired concerning the fate of the city; but he could be got to give us no anſwer. We entreated him with every expreſſion of tenderneſs and pity to tell us; but his ſenſes were quite wrapt up in the contemplation of the danger he had eſcaped. We offered him ſome victuals, but he ſeemed to loath the ſight. We ſtill perſiſted in our offices of kindneſs; but he only pointed to the place of the city, like one out of his ſenſes; and then running up into the woods, was never heard of after. Such was the fate of the city of Euphaemia: and as we continued our melancholy courſe along the ſhore, the whole coaſt, for the ſpace of two hundred miles, preſented nothing but the remains of cities; and men ſcattered, without an habitation, over the fields. Proceeding thus along, we at length ended our diſtreſsful voyage by arriving at Naples, after having eſcaped a thouſand dangers both at ſea and land."

The reader, I hope, will excuſe me for this long tranſlation from a favourite writer, and that the ſooner, as it contains ſome particulars relative' to earthquakes not to be found elſewhere. From the whole of theſe accounts we may gather, that the moſt concomitant circumſtances are theſe:

A rumbling ſound before the earthquake. This proceeds from the air, or fire, or both, forcing their way through the chaſms of the earth, and endeavouring to get free, which is alſo heard in volcanoes.

A violent agitation, or heaving of the ſea, ſometimes before and ſometimes after that at land. This agitation is only a ſimilar effect produced on the waters with that at land, and may be called, for the ſake of perſpicuity, a ſea-quake; and this, alſo, is produced by volcanoes.

A ſpouting up of waters to great heights. It is not eaſy to deſcribe the manner in which this is performed; but volcanoes alſo perform the ſame, Veſuvius being known frequently to eject a vaſt body of waters.

A rocking of the earth to and fro, and ſometimes a perpendicular bouncing, if it may be ſo called, of the ſame. This difference chiefly ariſes from the ſituation of the place with reſpect to the ſubterranean fire. Directly under, it lifts; at a farther diſtance, it rocks.

Some earthquakes ſeem to travel onward, and are felt in different countries at different hours the ſame day. This ariſes from the great ſhock being given to the earth at one place, and that being communicated onward by an undulatory motion, ſucceſſively affects different regions in its progreſs. As the blow given by a ſtone falling in a lake is not perceived at the ſhores till ſome time after the firſt concuſſion.

The ſhock is ſometimes inſtantaneous, like the exploſion of gunpowder; and ſometimes tremulous, and continuing for ſeveral minutes. The nearer the place where the ſhock is firſt given, the more inſtantaneous and ſimple it appears. At a greater diſtance the earth redoubles the firſt blow with a ſort of vibratory continuation.

As waters have generally ſo great a ſhare in producing earthquakes, it is not to be wondered that they ſhould generally follow thoſe breaches made by the force of fire, and appear in the great chaſms which the earthquake has opened.

Theſe are ſome of the moſt remarkable phoenomena of earthquakes, preſenting a frightful aſſemblage of the moſt terrible effects of air, earth, fire, and water.

The valley of Solfatara, near Naples, ſeems to exhibit, in a minuter degree, whatever is ſeen of this horrible kind on the great theatre of Nature. This plain, which is about twelve hundred feet long, and a thouſand broad, is emboſomed in mountains, and has in the middle of it a lake of noiſome blackiſh water, covered with a bitumen, that floats upon its ſurface. In every part of this plain, caverns appear ſmoking with ſulphur, and often emitting flames. The earth, wherever we walk over it, trembles beneath the feet. Noiſes of flames, and the hiſſing of waters, are heard at the bottom. The water ſometimes ſpouts up eight or ten feet high. The moſt noiſome fumes, foetid water, and ſulphureous vapours, offend the ſmell. A ſtone thrown into any of the caverns, is ejected again with conſiderable violence. Theſe appearances generally prevail when the ſea is any way diſturbed; and the whole ſeems to exhibit the appearance of an earthquake in miniature. However, in this ſmaller ſcene of wonders, as well as in the greater, there are many appearances for which perhaps we ſhall never account; and many queſtions may be aſked, which no conjectures can thoroughly reſolve. It was the fault of the philoſophers of the laſt age, to be more inquiſitive after the cauſes of things, than after the things themſelves. They ſeemed to think that a confeſſion of ignorance cancelled their claims to wiſdom: they, therefore, had a ſolution for every demand. But the preſent age has grown, if not more inquiſitive, at leaſt more modeſt; and none are now aſhamed of that ignorance which labour can neither remedy nor remove.

IT was ſaid in the former chapter, that the waters of the ſea were kept ſweet by their motion; without which they would ſoon putrefy, and ſpread univerſal infection. If we look for final cauſes, here, indeed, we have a great and an obvious one that preſents itſelf before us. Had the ſea been made without motion, and reſembling a pool of ſtagnant water, the nobler races of animated nature would ſhortly be at an end. Nothing would then be left alive but ſwarms of ill formed creatures, with ſcarce more than vegetable life; and ſubſiſting by putrefaction. Were this extenſive bed of waters entirely quieſcent, millions of the ſmaller reptile kinds would there find a proper retreat to breed and multiply in; they would find there no agitations, no concuſſion in the parts of the fluid to cruſh their feeble frames, or to force them from the places where they were bred: there they would multiply in ſecurity and eaſe, enjoy a ſhort life, and, putrefying, thus again give nouriſhment to numberleſs others, as little worthy of exiſtence as themſelves. But the motion of this great element, effectually deſtroys the number of theſe viler creatures; its currents, and its tides, produce continual agitations, the ſhock of which they are not able to endure; the parts of the fluid rub againſt each other, deſtroy all viſcidities; and the ocean, if I may ſo expreſs it, acquires health by exerciſe.

The moſt obvious motion of the ſea, and the moſt generally acknowledged, is that of its tides. This element is obſerved to flow for certain hours, from ſouth towards north; in which motion or flux, which laſts about ſix hours, the ſea gradually ſwells; ſo that entering the mouths of rivers, it drives back the river waters to their heads. After a continual flux of ſix hours, the ſea ſeems to reſt for a quarter of an hour; and then begins to ebb, or retire back again, from north to ſouth, for ſix hours more; in which time the waters ſinking, the rivers reſume their natural courſe. After a ſeeming pauſe of a quarter of an hour, the ſea again begins to flow as before: and thus it has alternately riſen and fallen, twice a day, ſince the creation.

This amazing appearance did not fail to excite the curioſity, as it did the wonder of the ancients. After ſome wild conjectures of the earlieſt philoſophers, it became well known, in the times of Pliny, that the tides were entirely under the influence, in a ſmall degree, of the ſun; but in a much greater of the moon. It was found that there was a flux and reflux of the ſea, in the ſpace of twelve hours fifty minutes, which is exactly the time of a lunar day. It was obſerved, that whenever the moon was in the meridian, or, in other words, as nearly as poſſible over any part of the ſea, that the ſea flowed to that part, and made a tide there; on the contrary, it was found, that when the moon left the meridian, the ſea began to flow back again from whence it came; and there might be ſaid to ebb. Thus far the waters of the ſea ſeemed very regularly to attend the motions of the moon. But as it appeared, likewiſe, that when the moon was in the oppoſite meridian, as far off as poſſible on the other ſide of the globe, that there was a tide on this ſide alſo; ſo that the moon produced two tides, one by her greateſt approach to us, and another by her greateſt diſtance from us: in other words, the moon, in once going round the earth, produced two tides, always at the ſame time; one on the part of the globe directly under her; and the other, on the part of the globe directly oppoſite.

Mankind continued for ſeveral ages content with knowing the general cauſe of theſe wonders, hopeleſs of diſcovering the particular manner of the moon's operation. Kepler was the firſt who conjectured that attraction was the principal cauſe; aſſerting, that the ſphere of the moon's operation extended to the earth, and drew up its waters. The preciſe manner in which this is done, was diſcovered by Newton.

The moon has been found, like all the reſt of the planets, to attract, and to be attracted by the earth. This attraction prevails throughout our whole planetary ſyſtem. The more matter there is contained in any body, the more it attracts: and its influence decreaſes in proportion as the diſtance, when ſquared, encreaſes. This being premiſed, let us ſee what muſt enſue upon ſuppoſing the moon in the meridian of any tract of the ſea. The ſurface of the water immediately under the moon, is nearer the moon than any other part of the globe is; and, therefore, muſt be more ſubject to its attraction than the waters any where elſe. The waters will, therefore, be attracted by the moon, and riſe in an heap; whoſe eminence will be the higheſt where the attraction is greateſt. In order to form this eminence, it is obvious that the ſurface, as well as the depths, will be agitated; and that wherever the water runs from one part, ſucceeding waters muſt run to fill up the ſpace it has left. Thus the waters of the ſea, running from all parts, to attend the motions of the moon, produce the flowing of the tide; and it is high tide at that part wherever the moon comes over it, or into its meridian.

But when the moon travels onward, and ceaſes to point over the place where the waters were juſt riſen, the cauſe here of their riſing ceaſing to operate, they will flow back by their natural gravity, into the lower parts from whence they had travelled; and this retiring of the waters will form the ebbing of the ſea.

Thus the firſt part of the demonſtration is obvious; ſince, in general, it requires no great ſagacity to conceive that the waters neareſt the moon are moſt attracted, or raiſed higheſt by the moon. But the other part of the demonſtration, namely, how there come to be high tides at the ſame time, on the oppoſite ſide of the globe, and where the waters are fartheſt from the moon, is not ſo eaſy to conceive. To comprehend this, it muſt be obſerved, that the part of the earth, and its waters, that are fartheſt from the moon, are the parts of all others that are leaſt attracted by the moon: it muſt alſo be obſerved, that all the waters, when the moon is on the oppoſite ſide of the earth, muſt be attracted by it in the ſame direction that the earth itſelf attracts them; that is, if I may ſo ſay, quite through the body of the earth, towards the moon itſelf. This, therefore, being conceived, it is plain that thoſe waters which are fartheſt from the moon, will have leſs weight than thoſe of any other part, on the ſame ſide of the globe; becauſe the moon's attraction, which conſpires with the earth's attraction, is there leaſt. Now, therefore, the waters fartheſt from the moon, having leſs weight, and being lighteſt, will be preſſed on all ſides, by thoſe that, having more attraction, are heavier: they will be preſſed, I ſay, on all ſides; and the heavier waters flowing in, will make them ſwell and riſe in an eminence directly oppoſite to that on the other ſide of the globe, cauſed by the more immediate influence of the moon.

In this manner the moon, in one diurnal revolution, produces two tides; one raiſed immediately under the ſphere of its influence, and the other directly oppoſite to it. As the moon travels, this vaſt body of waters rears upward, as if to watch its motions; and purſues the ſame conſtant rotation. However, in this great work of raiſing the tides, the ſun has no ſmall ſhare; it produces its own tides conſtantly every day, juſt as the moon does, but in a much leſs degree, becauſe the ſun is at an immenſely greater diſtance. Thus there are ſolar tides, and lunar tides. When the forces of theſe two great luminaries concur, which they always do when they are either in the ſame, or in oppoſite parts of the heavens, they jointly produce a much greater tide, than when they are ſo ſituated in the heavens, as each to make peculiar tides of their own. To expreſs the very ſame thing technically; in the conjunctions and oppoſitions of the ſun and moon, the attraction of the ſun conſpires with the attraction of the moon; by which means the high ſpring-tides are formed. But in the quadratures of the ſun and moon, the water raiſed by the one is depreſſed by the other; and hence the lower neap tides have their production. In a word, the tides are greateſt in the ſyzigies, and leaſt in the quadratures.

This theory well underſtood, and the aſtronomical terms previouſly known, it may readily be brought to explain the various appearances of the tides, if the earth were covered with a deep ſea, and the waters uninfluenced by ſhoals, currents, ſtraits, or tempeſts. But in every part of the ſea, near the ſhores, the geographer muſt come in to correct the calculations of the aſtronomer. For, by reaſon of the ſhallowneſs of ſome places, and the narrowneſs of the ſtraits in others, there ariſes a great diverſity in the effect, not to be accounted for without an exact knowledge of all the circumſtances of the place. In the great depths of the ocean, for inſtance, a very ſlow and imperceptible motion of the whole body of water will ſuffice to raiſe its ſurface ſeveral feet high; but if the ſame encreaſe of water is to be conveyed through a narrow channel, it muſt ruſh through it with the moſt impetuous rapidity. Thus in the Engliſh channel, and the German ocean, the tide is found to flow ſtrongeſt in thoſe places that are narroweſt; the ſame quantity of water being, in this caſe, to be driven through a ſmaller paſſage. It is often ſeen, therefore, pouring through a ſtreight with great force; and, by its rapidity, conſiderably raiſed above the ſurface of that part of the ocean into which it runs.

This ſhallowneſs and narrowneſs in many parts of the ſea, give alſo riſe to a peculiarity in the tides of ſome parts of the world. For in many places, and in our own ſeas in particular, the greateſt ſwell of the tide is not while the moon is at its meridian height, and directly over the place, but ſome time after it has declined from thence. The ſea, in this caſe, being obſtructed, purſues the moon with what diſpatch it can, but does not arrive with all its waters till long after the moon has ceaſed to operate. Laſtly, from this ſhallowneſs of the ſea, and from its being obſtructed by ſhoals and ſtreights, we may account for the Mediterranean, the Baltic, and the Black Sea, having no ſenſible tides. Theſe, though to us they ſeem very extenſive, are not however large enough to be affected by the influence of the moon; and as to their communication with the ocean, that is through ſuch narrow inlets, that it is impoſſible in a few hours time that they ſhould receive and return water enough to raiſe or depreſs them in any conſiderable degree.

In general, therefore, we may obſerve, that all tides are much higher, and more conſiderable in the torrid zone, than in the reſt of the ocean; the ſea in thoſe parts being generally deeper, and leſs affected by changeable winds, or winding ſhores Buffon, vol. ii. p. 187. . The greateſt tide we know of, is that at the mouth of the river Indus, where the water riſes thirty feet in height. How great, therefore, muſt have been the amazement of Alexander's ſoldiers at ſo ſtrange an appearance! They who always before had been accuſtomed only to the ſcarcely perceptible riſings of the Mediterranean, or the minute intumeſcence of the Black Sea, when made at once ſpectators of a river riſing and falling thirty feet in a few hours, muſt no doubt have felt the moſt extreme awe, and, as we are told Quintius Curtius. , a mixture of curioſity and apprehenſion. The tides are alſo remarkably high on the coaſts of Malay, in the ſtreights of Sunda, in the Red Sea, at the mouth of the river St. Lawrence, along the coaſts of China and Japan, at Panama, and in the gulph of Bengal. The tides at Tonquin, however, are the moſt remarkable in the world. In this part there is but one tide, and one ebb, in twenty-four hours; whereas, as we have ſaid before, in other places there are two. Beſides, there, twice in each month there is no tide at all, when the moon is near the equinoctial, the water being for ſome time quite ſtagnant. Theſe, with ſome other odd appearances attending the ſame phaenomena, were conſidered by many as inſcrutable; but Sir Iſaac Newton, with peculiar ſagacity, adjudged them to ariſe from the concurrence of two tides, one from the South Sea, and the other from the Indian Ocean. Of each of theſe tides there come ſucceſſively two every day; two at one time greater, and two at another that are leſs. The time between the arrival of the two greater, is conſidered by him as high tide; the time between the two leſſer, as ebb. In ſhort, with this clue, that great mathematician ſolved every appearance, and ſo eſtabliſhed his theory as to ſilence every oppoſer.

This fluctuation of the ſea from the tides, produces another, and more conſtant rotation of its waters, from the eaſt to the weſt, in this reſpect following the courſe of the moon. This may be conſidered as one great and general current of the waters of the ſea; and although it be not every where diſtinguiſhable, it is nevertheleſs every where exiſtent, except when oppoſed by ſome particular current or eddy, produced by partial and local cauſes. This tendency of the ſea towards the weſt, is plainly perceivable in all the great ſtreights of the ocean; as, for inſtance, in thoſe of Magellan; where the tide running in from the eaſt, riſes twenty feet high, and continues flowing ſix hours; whereas the ebb continues but two hours, and the current is directed to the weſt. This proves that the flux is not equal to the reflux; and that from both reſults a motion of the ſea weſtward, which is more powerful during the time of the flux than the reflux.

But this motion weſtward has been ſenſibly obſerved by navigators, in their paſſage back from India to Madagaſcar, and ſo on to Africa. In the great Pacific Ocean alſo, it is very perceivable: but the places where it is moſt obvious are, as was ſaid, in thoſe ſtreights which join one ocean to another. In the ſtreights between the Maldivia iſlands, in the gulph of Mexico, between Cuba and Jucatan. In the ſtreights of the gulph of Paria, the motion is ſo violent that it hath received the appellation of the Dragon's Mouth. Northward, in the ſea of Canada, in Waigat's ſtreights, in the ſtreights of Java, and, in ſhort, in every ſtreight where the ocean on one part pours into the ocean on the other. In this manner, therefore, is the ſea carried with an unceaſing circulation round the globe; and, at the ſame time that its waters are puſhed back and forward with the tide, they have thus a progreſſive current to the weſt, which, though leſs obſervable, is not the leſs real.

Beſides theſe two general motions of the ſea, there are others which are particular to many parts of it, and are called currents. Theſe are found to run in all directions, eaſt, weſt, north, and ſouth; being formed, as was ſaid above, by various cauſes; the prominence of the ſhores, the narrowneſs of the ſtreigths, the variations of the wind, and the inequalities at the bottom. Theſe, though no great object to the philoſopher, as their cauſes are generally local and obvious, are nevertheleſs of the moſt material conſequence to the mariner; and, without a knowledge of which, he could never ſucceed. It often has happened, that when a ſhip has unknowingly got into one of theſe, every thing ſeems to go forward with ſucceſs, the mariners ſuppoſe themſelves every hour approaching their wiſh'd-for port, the wind fills their ſails, and the ſhip's prow ſeems to divide the water; but, at laſt, by miſerable experience they find, that inſtead of going forward, they have been all the time receding. The buſineſs of currents, therefore, makes a conſiderable article in navigation; and the direction of their ſtream, and their rapidity, has been carefully ſet down. This ſome do by the obſervation of the ſurface of the current; or by the driving of the froth along the ſhore; or by throwing out what is called the log-line, with a buoy made for that purpoſe, and by the direction and motion of this, they judge of the ſetting, and the rapidity of the current.

Theſe currents are generally found to be moſt violent under the equator, where indeed all the motions of the ocean are moſt perceivable. Along the coaſts of Guinea, if a ſhip happens to overſhoot the mouth of any river it is bound to, the current prevents its return; ſo that it is obliged to ſteer out to ſea, and take a very large compaſs, in order to correct the former miſtake. Theſe ſet in a contrary direction to the general motion of the ſea weſtward; and that ſo ſtrongly, that a paſſage which with the current is gone in two days, is with difficulty performed in ſix weeks againſt it. However, they do not extend above twenty leagues from the coaſt; and ſhips going to the Eaſt-Indies, take care not to come within the ſphere of their action. At Sumatra, the currents, which are extremely rapid, run from ſouth to north: there are alſo ſtrong currents between Madagaſcar and the Cape of Good Hope. On the weſtern coaſts of America, the current always runs from the ſouth to the north, where a ſouth wind, continually blowing, moſt probably occaſions this phaenomena. But the currents that are moſt remarkable, are thoſe continually flowing into the Mediterranean ſea, both from the ocean by the ſtreights of Gibraltar, and at its other extremity, from the Euxine ſea by the Archipelago. This is one of the moſt extraordinary appearances in nature, this large ſea receiving not only the numerous rivers that fall into it, ſuch as the Nile, the Rhone, and the Po, but alſo a very great influx from the Euxine ſea on one part, and the ocean on the other. At the ſame time, it is ſeen to return none of thoſe waters it is thus known to receive: outlets running from it there are none; no rivers but ſuch as bring it freſh ſupplies; no ſtreights but what are conſtantly pouring their waters into it: it has therefore been the wonder of mankind in every age, how, and by what means this vaſt concourſe of waters are diſpoſed of; or how this ſea, which is always receiving, and never returning, is no way fuller than before. In order to account for this, ſome have ſaid, that the water was re-conveyed by ſubterraneous paſſages into the Red Sea Kircher Mund. Subt. vol. i. . There is a ſtory told of an Arabian califf, who caught a dolphin in this ſea, admiring the beauty of which, he let it go again, having previouſly marked it by a ring of iron. Some time after a dolphin was caught in the Red Sea, and quickly known by the ring to be the ſame that had been taken in the Mediterranean before. Such, however, as have not been willing to found their opinions upon a ſtory, have attempted to account for the diſpoſal of the waters of the Mediterranean by evaporation. For this purpoſe they have entered into long calculations upon the extent of its ſurface, and the quantity of water that would be raiſed from ſuch a ſurface in a year. They then compute how much water runs in by its rivers and ſtreights in that time; and find, that the quantity exhauſted by evaporation, greatly exceeds the quantity ſupplied by rivers and ſeas. And this ſolution, no doubt would be ſatisfactory, did not the ocean, and the Euxine, evaporate as well as the Mediterranean: and as theſe are ſubject to the ſame drain, it muſt follow, that all the ſeas will in this reſpect be upon a par; and, therefore, there muſt be ſome other cauſe for this unperceived drain, and continual ſupply. This ſeems to be ſatisfactorily enough accounted for by Doctor Smith, who ſuppoſes an under current running through the ſtreights of Gibraltar to carry out as much water into the ocean, as the upper current continually carries in from it. To confirm this, he obſerves, that nearer home, between the north and ſouth foreland, the tide is known to run one way at top, and the ebb another way at bottom. This double current he alſo confirms by an experiment communicated to him by an able ſeaman, who being with one of the king's frigates in the Baltic, found he went with his boat into the mid-ſtream, and was carried violently by the current; upon which a baſket was ſunk, with a large cannonball, to a certain depth of water, which gave a check to the boat's motion; as the baſket ſunk ſtill lower, the boat was driven, by the force of the water below, againſt the upper current; and the lower the baſket was let down, the ſtronger the under current was found, and the quicker was the boat's motion againſt the upper ſtream, which ſeemed not to be above four fathom deep. From hence we may readily infer, that the ſame cauſe may operate at the ſtreights of Gibraltar; and that while the Mediterranean ſeems repleniſhing at top, it may be emptying at bottom.

The number of the currents at ſea are impoſſible to be recounted, nor indeed are they always known; new ones are daily produced by a variety of cauſes, and as quickly diſappear. When a regular current is oppoſed by another in a narrow ſtreight, or where the bottom of the ſea is very uneven, a whirlpool is often formed. Theſe were formerly conſidered as the moſt formidable obſtructions to navigation, and the ancient poets and hiſtorians ſpeak of them with terror; they are deſcribed as ſwallowing up ſhips, and daſhing them againſt the rocks at the bottom: apprehenſion did not fail to add imaginary terrors to the deſcription, and placed at the center of the whirlpool a dreadful den, fraught with monſters whoſe howlings ſerved to add new horrors to the daſhings of the deep. Mankind at preſent, however, view theſe eddies of the ſea with very little apprehenſion; and ſome have wondered how the ancients could have ſo much overcharged their deſcriptions. But all this is very naturally accounted for. In thoſe times when navigation was as yet but beginning, and the ſlighteſt concuſſion of the waves generally ſent the poor adventurer to the bottom, it is not to be wondered at that he was terrified at the violent agitations in one of theſe. When his little ſhip, but ill fitted for oppoſing the fury of the ſea, was got within the vortex, there was then no poſſibility of ever returning. To add to the fatality, they were always near the ſhore; and along the ſhore was the only place where this ill provided mariner durſt venture to ſail. Theſe were, therefore, dreadful impediments to his navigation; for if he attempted to paſs between them and the ſhore, he was ſometimes ſucked in by the eddy; and if he attempted to avoid them out at ſea, he was often ſunk by the ſtorm. But in our time, and in our preſent improved ſtate of navigation, Charybdis, and the Euripus, with all the other irregular currents of the Mediterranean, are no longer formidable. Mr. Addiſon not attending to this train of thinking, upon paſſing through the ſtreights of Sicily, was ſurpriſed at the little there was of terror in the preſent appearance of Sylla and Charybdis; and ſeems to be of opinion, that their agitations are much diminiſhed ſince the times of antiquity. In fact, from the reaſons above, all the wonders of the Mediterranean ſea are deſcribed in much higher colours than they merit, to us who are acquainted with the more magnificent terrors of the ocean. The Mediterranean is one of the ſmootheſt and moſt gentle ſeas in the world; its tides are ſcarce perceivable, except in the gulph of Venice, and ſhipwrecks are leſs known there than in any other part of the world.

It is in the ocean, therefore, that theſe whirlpools are particularly dangerous, where the tides are violent, and the tempeſts fierce. To mention only one, that called the Maelſtroom, upon the coaſts of Norway, which is conſidered as the moſt dreadful and voracious in the world. The name it has received from the natives, ſignifies the navel of the ſea, ſince they ſuppoſe that a great ſhare of the water of the ſea is ſucked up and diſcharged by its vortex. A minute deſcription of the internal parts is not to be expected, ſince none who were there ever returned to bring back information. The body of the waters that form this whirlpool, are extended in a circle above thirteen miles in circumference Kircher Mund. Subt. vol. i. p. 156. . In the midſt of this ſtands a rock, againſt which the tide in its ebb is daſhed with inconceivable fury. At this time it inſtantly ſwallows up all things that come within the ſphere of its violence, trees, timber, and ſhipping. No ſkill in the mariner, nor ſtrength of rowing, can work an eſcape: the ſailor at the helm finds the ſhip at firſt go in a current oppoſite to his intentions; his veſſel's motion, tho' ſlow in the beginning, becomes every moment more rapid; it goes round in circles ſtill narrower and narrower, till at laſt it is daſhed againſt the rocks, and inſtantly diſappears: nor is it ſeen again for ſix hours: till the tide flowing, it is vomited forth with the ſame violence with which it was drawn in. The noiſe of this dreadful vortex ſtill farther contributes to encreaſe its terror, which with the daſhing of the waters, and the dreadful valley, if it may be ſo called, cauſed by their circulation, makes one of the moſt tremendous objects in nature.

FROM what has been ſaid, as well of the earth as of the ſea, they both appear to be in continual fluctuation. The earth, the common promptuary that ſupplies ſubſiſtence to men, animals, and vegetables, is continually furniſhing its ſtores to their ſupport. But the matter which is thus derived from it, is ſoon reſtored and laid down again to be prepared for freſh mutations. The tranſmigration of ſouls is no doubt falſe and whimſical; but nothing can be more certain than the tranſmigration of bodies: the ſpoils of the meaneſt reptile may go to the formation of a prince; and, on the contrary, as the poet has it, the body of Caeſar may be employed in ſtopping a beer barrel. From this, and other cauſes, therefore, the earth is in continual change. Its internal fires, the deviation of its rivers, and the falling of its mountains, are daily altering its ſurface; and geography can ſcarce recollect the lakes and the vallies that hiſtory once deſcribed.

But theſe changes are nothing to the inſtability of the ocean. It would ſeem that inquietude was as natural to it as its fluidity. It is firſt ſeen with a conſtant and equable motion going towards the weſt; the tides then interrupt this progreſſion, and for a time drive the waters in a contrary direction; beſide theſe agitations, the currents act their part in a ſmaller ſphere, being generally greateſt where the other motions of the ſea are leaſt; namely, neareſt the ſhore: the winds alſo contribute their ſhare in this univerſal fluctuation; ſo that ſcarce any part of the ſea is wholly ſeen to ſtagnate.

As this great element is thus changed, and continually labouring internally, it may be readily ſuppoſed that it produces correſpondent changes upon its ſhores, and thoſe parts of the earth ſubject to its influence. In fact, it is every day making conſiderable alterations, either by overflowing its ſhores in one place, or deſerting them in others; by covering over whole tracts of country, that were cultivated and peopled, at one time; or by leaving its bed to be appropriated to the purpoſes of vegetation, and to ſupply a new theatre for human induſtry at another.

In this ſtruggle between the earth and the ſea for dominion, the greateſt number of our ſhores ſeem to defy the whole rage of the waves, both by their height, and the rocky materials of which they are compoſed. The coaſts of Italy, for inſtance Buffon, vol. ii. p. 199. , are bordered with rocks of marble of different kinds, the quarries of which may eaſily be diſtinguiſhed at a diſtance from ſea, and appear like perpendicular columns, of the moſt beautiful kinds of marble, ranged along the ſhore. In general, the coaſts of France, from Breſt to Bourdeaux, are compoſed of rocks; as are alſo thoſe of Spain and England, which defend the land, and only are interrupted here and there to give an egreſs to rivers, and to grant the conveniences of bays and harbours to our ſhipping. It may be in general remarked, that wherever the ſea is moſt violent and furious, there the boldeſt ſhores, and of the moſt compact materials, are found to oppoſe it. There are many ſhores ſeveral hundred feet perpendicular, againſt which the ſea, when ſwollen with tides or ſtorms, riſes and beats with inconceivable fury. In Idem, vol. ii. p. 191. the Orkneys, where the ſhores are thus formed, it ſometimes, when agitated by a ſtorm, riſes two hundred feet perpendicular, and daſhes up its ſpray, together with ſand, and other ſubſtances that compoſe its bottom, upon land, like ſhowers of rain.

From hence, therefore, we may conceive how the violence of the ſea, and the boldneſs of the ſhore, may be ſaid to have made each other. Where the ſea meets no obſtacles, it ſpreads its waters with a gentle intumeſcence, till all its power is deſtroyed, by its wanting depth to aid its motion. But when its progreſs is checked in the midſt, by the prominence of rocks, or the abrupt elevation of the land, it daſhes with all the force of its depth againſt the obſtacle, and forms, by its repeated violence, that abruptneſs of the ſhore which confines its impetuoſity. Where the ſea is extremely deep, or very much vexed by tempeſts, it is no ſmall obſtacle that can confine its rage; and for this reaſon we ſee the boldeſt ſhores projected againſt the deepeſt waters; all leſs impediments having long before been ſurmounted and waſhed away. Perhaps of all the ſhores in the world, there is not one ſo high as that to the weſt of St. Kilda, which, upon a late admeaſurement Deſcription of St. Kilda. , was found to be ſix hundred fathom perpendicular above the ſurface of the ſea. Here alſo, the ſea is deep, turbulent, and ſtormy; ſo that it requires great force in the ſhore to oppoſe its violence. In many parts of the world, and particularly upon the coaſts of the Eaſt Indies, the ſhores, though not high above water, are generally very deep, and conſequently the waves roll againſt land with great weight and irregularity. This riſing of the waves againſt the ſhore, is called by mariners, the ſurf of the ſea; and in ſhipwrecks is generally fatal to ſuch as attempt to ſwim on ſhore. In this caſe, no dexterity in the ſwimmer, no float he can uſe, neither ſwimming girdle nor cork jacket will ſave him; the weight of the ſuperincumbent wave breaks upon him at once, and cruſhes him with certain ruin. Some few of the natives, however, have the art of ſwimming and of navigating their little boats near thoſe ſhores, where an European is ſure of inſtant deſtruction.

In places where the force of the ſea is leſs violent, or its tides leſs rapid, the ſhores are generally ſeen to deſcend with a more gradual declivity. Over theſe, the waters of the tide ſteal by almoſt imperceptible degrees, covering them for a large extent, and leaving them bare on its receſs. Upon theſe ſhores, as was ſaid, the ſea ſeldom beats with any great violence, as a large wave has not depth ſufficient to float it onwards, ſo that here only are to be ſeen gentle ſurges making calmly towards land, and leſſening as they approach. As the ſea, in the former deſcription, is generally ſeen to preſent proſpects of tumult, and uproar, here it more uſually exhibits a ſcene of repoſe and tranquil beauty. Its waters, which when ſurveyed from the precipice, afforded a muddy greeniſh hue, ariſing from their depth and poſition to the eye Newton's Optics, p. 163-167. , when regarded from a ſhelving ſhore, wear the colour of the ſky, and ſeem riſing to meet it. The deafening noiſe of the deep ſea, is here converted into gentle murmurs; inſtead of the water's daſhing againſt the face of the rock, it advances and recedes, ſtill going forward, but with juſt force enough to puſh its weeds and ſhells, by inſenſible approaches, to the ſhore.

There are ſtill other ſhores, beſide thoſe already deſcribed, which either have been raiſed by art to oppoſe the ſea's approaches, or from the ſea's gaining ground, are threatened with imminent deſtruction. The ſea's being thus ſeen to give and take away lands at pleaſure, is, without queſtion, one of the moſt extraordinary conſiderations in all natural hiſtory. In ſome places it is ſeen to obtain the ſuperiority by ſlow and certain approaches; or to burſt in at once, and overwhelm all things in undiſtinguiſhed deſtruction; in other places it departs from its ſhores, and where its waters have been known to rage, it leaves fields covered with the moſt beautiful verdure.

The formation of new lands by the ſea's continually bringing its ſediment to one place, and by the accumulation of its ſands in another, is eaſily conceived. We have had many inſtances of this in England. The iſland of Oxney, which is adjacent to Romney-marſh, was produced in this manner. This had for a long time been a low level, continually in danger of being overflown by the river Rother; but the ſea, by its depoſitions, has gradually raiſed the bottom of the river, while it has hollowed the mouth; ſo that the one is ſufficiently ſecured from inundations, and the other is deep enough to admit ſhips of conſiderable burthen. The like alſo may be ſeen at that bank called the Dogger-ſands, where two tides meet, and which thus receive new increaſe every day, ſo that in time the place ſeems to promiſe fair for being habitable earth. On many parts of the coaſts of France, England, Holland, Germany, and Pruſſia, the ſea has been ſenſibly known to retire Buffon, vol. vi. p. 424. . Hubert Thomas aſſerts, in his Deſcription of the Country of Liege, that the ſea formerly encompaſſed the city of Tongres, which, however, is at preſent thirty-five leagues diſtant from it: this aſſertion he ſupports by many ſtrong reaſons; and among others, by the iron rings fixed in the walls of the town, for faſtening the ſhips that came into the port. In Italy there is a conſiderable piece of ground gained at the mouth of the river Arno; and Ravenna, that once ſtood by the ſea-ſide is now conſiderably removed from the ſame. But we need ſcarce mention theſe, when we find that the whole kingdom of Holland ſeems to be a conqueſt upon the ſea, and in a manner reſcued from its boſom. The ſurface of the earth, in this country, is below the level of the bed of the ſea; and I remember, upon approaching the coaſt, to have looked down upon it from the ſea, as into a valley; however, it is every day riſing higher by the depoſitions made upon it, both by the ſea, the Rhine, and the Meuſe; and thoſe parts which formerly admitted large men of war, are now known to be too ſhallow to receive ſhips of very moderate burthen Buffon, vol. vi. p. 424. . The province of Jucatan, a peninſula in the gulph of Mexico, was formerly a part of the ſea: this tract, which ſtretches out into the ocean an hundred leagues, and which is above thirty broad, is every where, at a moderate depth below the ſurface, compoſed of ſhells, which evince that its land once formed the bed of the ſea. In France, the town of Aigues Mortes was a port in the times of St. Louis, which is now removed more than four miles from the ſea. Pſalmodi, in the ſame kingdom, was an iſland in the year 815, but is now more than ſix miles from the ſhore. All along the coaſts of Norfolk, I am very well aſſured, that in the memory of man, the ſea has gained fifty yards in ſome places, and has loſt as much in others.

Thus numerous, therefore, are the inſtances of new lands having been produced from the ſea, which, as we ſee, is brought about two different ways: firſt, by the waters raiſing banks of ſand and mud where their ſediment is depoſited; and ſecondly, by their relinquiſhing the ſhore entirely, and leaving it unoccupied to the induſtry of man.

But as the ſea has been thus known to recede from ſome lands, ſo has it, by fatal experience, been found to encroach upon others: and, probably, theſe depredations on one part of the ſhore, may account for their dereliction from another; for the current which reſted upon ſome certain bank, having got an egreſs in ſome other place, it no longer preſſes upon its former bed, but pours all its ſtream into the new entrance, ſo that every inundation of the ſea may be attended with ſome correſpondent dereliction of another ſhore.

However this be, we have numerous hiſtories of the ſea's inundations, and its burying whole provinces in its boſom. Many countries that have been thus deſtroyed, ſtill bear melancholy witneſs to the truth of hiſtory; and ſhew the tops of their houſes, and the ſpires of their ſteeples, ſtill ſtanding at the bottom of the water. One of the moſt conſiderable inundations we have in hiſtory, is that which happened in the reign of Henry I. which overflowed the eſtates of the Earl Godwin, and forms now that bank called the Goodwin ſands. In the year 1546, a ſimilar irruption of the ſea deſtroyed an hundred thouſand perſons in the territory of Dort; and yet a greater number round Dullart. In Friezland, and Zealand, there were more than three hundred villages overwhelmed; and their remains continue ſtill viſible at the bottom of the water in a clear day. The Baltic ſea has, by ſlow degrees, covered a large part of Pomerania; and, among others, deſtroyed and overwhelmed the famous port of Vineta. In the ſame manner, the Norwegian ſea has formed ſeveral little iſlands from the main land, and ſtill daily advances upon the continent. The German ſea has advanced upon the ſhores of Holland, near Catt, ſo that the ruins of an ancient citadel of the Romans, which was formerly built upon this coaſt, are now actually under water. To theſe accidents ſeveral more might be added; our own hiſtorians, and thoſe of other countries, abound with them; almoſt every flat ſhore of any extent, being able to ſhew ſomething that it has loſt, or ſomething that it has gained from the ſea.

There are ſome ſhores on which the ſea has made temporary depredations; where it has overflowed, and after remaining perhaps ſome ages, it has again retired of its own accord, or been driven back by the induſtry of man Buffon, vol. ii. p. 425. . There are many lands in Norway, Scotland, and the Maldivia iſlands, that are at one time covered with water, and at another free. The country round the Iſle of Ely, in the times of Bede, about a thouſand years ago, was one of the moſt delightful ſpots in the whole kingdom. It was not only richly cultivated, and produced all the neceſſaries of life, but grapes alſo that afforded the moſt excellent wine. The accounts of that time are copious in the deſcription of its verdure and fertility; its rich paſtures, covered with flowers and herbage; its beautiful ſhades, and wholſome air. But the ſea breaking in, upon the land, overwhelmed the whole country, took poſſeſſion of the ſoil, and totally deſtroyed one of the moſt beautiful vallies in the world. Its air, from being dry and healthful, from that time became moſt unwholſome, and clogged with vapours; and the ſmall part of the country that, by being higher than the reſt, eſcaped the deluge, was ſoon rendered uninhabitable, from its noxious vapours. Thus this country continued under water for ſome centuries; till, at laſt, the ſea, by the ſame caprice which had prompted its invaſions, began to abandon the the earth in like manner. It has continued for ſome ages to relinquiſh its former conqueſts; and although the inhabitants can neither boaſt the longevity, nor the luxuries of their former pre-occupants, yet they find ample means of ſubſiſtence; and if they happen to ſurvive the firſt years of their reſidence there, they are often known to arrive at a good old age.

But although hiſtory be ſilent as to many other inundations of the like kind, where the ſea has overflowed the country, and afterwards retired, yet we have numberleſs teſtimonies of another nature, that prove it beyond the poſſibility of doubt: I mean thoſe numerous trees that are found buried at conſiderable depths in places where either rivers, or the ſea, has accidentally overflown Buffon, vol. ii. p. 403. . At the mouth of the river Neſs, near Bruges, in Flanders, at the depth of fifty feet, are found great quantities of trees lying as cloſe to each other as they do in a wood: the trunks, the branches, and the leaves, are in ſuch perfect preſervation, that the particular kind of each tree may inſtantly be known. About five hundred years ago, this very ground was known to have been covered with the ſea; nor is there any hiſtory or tradition of its having been dry ground, which we can have no doubt muſt have been the caſe. Thus we ſee a country flouriſhing in verdure, producing large foreſts, and trees of various kinds, overwhelmed by the ſea. We ſee this element depoſiting its ſediment to an heighth of fifty feet; and its waters muſt, therefore, have riſen much higher. We ſee the ſame, after it has thus overwhelmed, and ſunk the land ſo deep beneath its ſlime, capriciouſly retiring from the ſame coaſts, and leaving that habitable once more, which it had formerly deſtroyed. All this is wonderful; and perhaps, inſtead of attempting to enquire after the cauſe, which has hitherto been inſcrutable, it will beſt become us to reſt ſatisfied with admiration.

At the city of Modena in Italy, and about four miles round it, wherever it is dug, when the workmen arrive at the depth of ſixty-three feet, they come to a bed of chalk, which they bore with an augre five feet deep: they then withdraw from the pit, before the augre is removed, and upon its extraction, the water burſts up through the aperture with great violence, and quickly fills this new made well, which continues full, and is affected neither by rains nor droughts. But that which is moſt remarkable in this operation, is the layers of earth as we deſcend. At the depth of fourteen feet, are found the ruins of an ancient city, paved ſtreets, houſes, floors, and different pieces of Moſaic. Under this is found a ſolid earth, that would induce one to think had never been removed; however, under it is found a ſoft oozy earth, made up of vegetables; and at twenty-ſix feet depth, large trees entire, ſuch as walnut-trees, with the walnuts ſtill ſticking on the ſtem, and their leaves and branches in exact preſervation. At twenty-eight feet deep, a ſoft chalk is found, mixed with a vaſt quantity of ſhells; and this bed is eleven feet thick. Under this, vegetables are found again, with leaves, and branches of trees as before; and thus alternately chalk and vegetable earth to the depth of ſixty-three feet. Theſe are the layers wherever the workmen attempt to bore; while in many of them, they alſo find pieces of charcoal, bones, and bits of iron. From this deſcription, therefore, it appears, that this country has been alternately overflowed and deſerted by the ſea, one age after another: nor were theſe overflowings and retirings of trifling depth, or of ſhort continuance. When the ſea burſt in, it muſt have been a long time in overwhelming the branches of the fallen foreſt with its ſediment; and ſtill longer in forming a regular bed of ſhells eleven feet over them. It muſt have, therefore, taken an age, at leaſt, to make any one of theſe layers; and we may conclude, that it muſt have been many ages employed in the production of them all. The land alſo, upon being deſerted, muſt have had time to grow compact, to gather freſh fertility, and to be drained of its waters before it could be diſpoſed to vegetation; or before its trees could have ſhot forth again to maturity.

We have inſtances nearer home of the ſame kind, given us in the Philoſophical Tranſactions; one of them by Mr. Derham. An inundation of the ſea, at Dagenham, in Eſſex, laying bare a part of the adjacent paſture, for above two hundred feet wide, and, in ſome places, twenty deep, it diſcovered a number of trees that had lain there for many ages before; theſe trees, by lying long under ground, were become black and hard, and their fibres ſo tough, that one might as eaſily break a wire, as any of them: they lay ſo thick in the place where they were found, that in many parts he could ſtep from one to another: he conceived alſo, that not only all the adjacent marſhes, for ſeveral hundred acres, were covered underneath with ſuch timber, but alſo the marſhes along the mouth of the Thames, for ſeveral miles. The meeting with theſe trees at ſuch depths, he aſcribes to the ſediment of the river, and the tides, which conſtantly waſhing over them, have always left ſome part of their ſubſtance behind, ſo as, by repeated alluvions, to work a bed of vegetable earth over them, to the height at which he found it.

The levels of Hatfield-Chace, in Yorkſhire, a tract of above eighteen thouſand acres, which was yearly overflown, was reduced to arable and paſture-land, by one Sir Cornelius Vermuſden, a Dutchman. At the bottom of this wide extent, are found millions of the roots and bodies of trees, of ſuch as this iſland either formerly did, or does at preſent produce. The roots of all ſtand in their proper poſtures; and by them, as thick as ever they could grow, the reſpective trunks of each, ſome above thirty yards long. The oaks, ſome of which have been ſold for fifteen pounds a piece, are as black as ebony, very laſting, and cloſe grained. The aſh-trees are as ſoft as earth, and are commonly cut in pieces by the workmen's ſpades, and as ſoon as flung up into the open air, turn to duſt. But all the reſt, even the willows themſelves, which are ſofter than the aſh, preſerve their ſubſtance and texture to this very day. Some of the firs appear to have vegetated, even after they were fallen, and to have, from their branches, ſtruck up large trees, as great as the parent trunk. It is obſervable, that many of theſe trees have been burnt, ſome quite through, ſome on one ſide, ſome have been found chopped and ſquared, others riven with great wooden wedges, all ſufficiently manifeſting, that the country which was deluged, had formerly been inhabited. Near a great root of one tree, were found eight coins of the Roman emperors; and, in ſome places, the marks of the ridge and furrow were plainly perceivable, which teſtified that the ground had formerly been patient of cultivation.

The learned naturaliſt who has given this deſcription Phil. Tranſ. vol. iv. part ii. p. 214. , has pretty plainly evinced, that this foreſt, in particular, muſt have been thus levelled by the Romans; and that the falling of the trees, muſt have contributed to the accumulation of the waters. "The Romans," ſays he, "when the Britons fled, always purſued them into the fortreſſes of low woods, and miry foreſts: in theſe, the wild natives found ſhelter; and, when opportunity offered, iſſued out, and fell upon their invaders without mercy. In this manner, the Romans were at length ſo harraſſed, that orders were iſſued out for cutting down all the woods and foreſts in Britain. In order to effect this, and deſtroy the enemy the eaſier, they ſet fire to the woods, compoſed of pines, and other inflamable timber, which ſpreading, the conflagration deſtroyed not only the foreſt, but infinite numbers of the wretched inhabitants who had taken ſhelter therein: When the pine-trees had thus done what miſchief they could, the Romans then brought their army nearer, and, with whole legions of the captive Britons, cut down moſt of the trees that were yet left ſtanding; leaving only here and there ſome great trees untouched, as monuments of their fury. Theſe, unneedful of their labour, being deſtitute of the ſupport of the underwood, and of their neighbouring trees, were eaſily overthrown by the winds, and, without interruption, remained on the places where they happened to fall. The foreſt, thus fallen, muſt neceſſarily have ſtopped up the currents, both from land and ſea; and turned into great lakes, what were before but temporary ſtreams. The working of the waters here, the conſumption and decay of rotten boughs and branches, and the vaſt encreaſe of water-moſs which flouriſhes upon marſhy grounds, ſoon formed a covering over the trunks of the fallen trees, and raiſed the earth ſeveral feet above its former level. The earth thus every day ſwelling, by a continual encreaſe from the ſediment of the waters, and by the lightneſs of the vegetable ſubſtances of which it was compoſed, ſoon overtopt the waters by which this intumeſcence was at firſt effected; ſo that it entirely got rid of its inundations, or only demanded a ſlight aſſiſtance from man for that purpoſe." And this may be the origin of all bogs whatſoever, which are formed by the putrefaction of vegetable ſubſtances, mixed with the mud and ſlime depoſited by waters, and at length acquiring a ſufficient conſiſtency.

From this we ſee what powerful effects the ſea is capable of producing upon its ſhores, either by overflowing ſome, or deſerting others; by altering the direction of theſe, and rendering thoſe craggy and precipitate, which before were ſhelving. But the influence it has upon theſe, is nothing to that which it has upon that great body of earth which forms its bottom. It is at the bottom of the ſea that the greateſt wonders are performed, and the moſt rapid changes are produced; it is there that the motion of the tides and the currents have their whole force, and agitate the ſubſtances of which their bed is compoſed. But all theſe are almoſt wholly hid from human curioſity: the miracles of the deep are performed in ſecret; and we have but little information from its abyſſes, except what we receive by inſpection at very ſhallow depths, or by the plummet, or from divers, who are known to deſcend from twenty to thirty fathom Phil. Tranſ. vol. iv. part ii. p. 192. .

The eye can reach but a very ſhort way into the depths of the ſea; and that only when its ſurface is glaſſy and ſerene. In many ſeas it perceives nothing but a bright ſandy plain at bottom, extending for ſeveral hundred miles, without an intervening object. But in others, particularly in the Red Sea, it is very different: the whole bottom of this extenſive bed of waters is, literally ſpeaking, a foreſt of ſubmarine plants, and corals formed by inſects for their habitation, ſometimes branching out to a great extent. Here are ſeen the madrepores, the ſponges, moſſes, ſea muſhrooms, and other marine productions, covering every part of the bottom; ſo that ſome have even ſuppoſed the ſea to have taken its name from the colour of its plants below. However, theſe plants are by no means peculiar to this ſea, as they are found in great quantities in the Perſian gulph, along the coaſts of Africa, and thoſe of Provence and Catalonia.

The bottom of many parts of the ſea near America, preſents a very different, though a very beautiful appearance. This is covered with vegetables, which make it look as green as a meadow, and beneath are ſeen thouſands of turtles, and other ſea animals, feeding thereon.

In order to extend our knowledge of the ſea to greater depths, recourſe has been had to the plummet; which is generally made of a lump of lead of about forty pounds weight, faſtened to a cord Buffon, vol. ii. p. 5. . This, however, only anſwers in moderate depths; for when a deep ſea is to be ſounded, the matter of which the cord is compoſed, being lighter than the water, floats upon it, and when let down to a conſiderable depth, its length ſo encreaſes its ſurface, that it is often ſufficient to prevent the lead from ſinking; ſo that this may be the reaſon that ſome parts of the ſea are ſaid to have no bottom.

In general, we learn from the plummet, that the bottom of the ſea is tolerably even where it has been examined; and that the farther from the ſhore, the ſea is in general the deeper. Notwithſtanding, now and then, in the midſt of a great and unfathomable ocean, we often find an iſland raiſing its head, and ſingly braving its fury. Such iſlands may be conſidered as the mountains of the deep; and, could we for a moment imagine the waters of the ocean removed, or dried away, we ſhould probably find the inequalities of its bed reſembling thoſe that are found at land. Here extenſive plains; there valleys; and, in many places, mountains of amazing height. M. Buache has actually given us a map of that part of its bottom, which lies between Africa and America, taken from the ſeveral ſoundings of mariners: in it we find the ſame uneven ſurface that we do upon land, the ſame eminences, and the ſame depreſſions. In ſuch an imaginary proſpect, however, there would be this difference, that as the tops of land mountains appear the moſt barren and rocky, the tops of ſea-mountains would be found the moſt verdant and fruitful.

The plummet, which thus gives us ſome idea of the inequalities of the bottom, leaves us totally in the dark as to every other particular; recourſe, therefore, has been had to divers: theſe, either being bred up in this dangerous way of life, and accuſtomed to remain ſome time under water without breathing, or aſſiſted by means of a diving-bell, have been able to return ſome confuſed and uncertain accounts of the places below. In the great diving-bell improved by Doctor Halley, which was large enough to contain five men, and was ſupplied with freſh air by buckets, that alternately roſe and fell, they deſcended fifty fathom. In this huge machine, which was let down from the maſt of the ſhip, the doctor himſelf went down to the bottom, where, when the ſea was clear, and eſpecially when the ſun ſhone, he could ſee perfectly well to write or read, and much more to take up any thing that was underneath: at other times, when the water was troubled and thick, it was as dark as night below, ſo that he was obliged to keep a candle lighted at the bottom. But there is one thing very remarkable, which is, that the water which from above was uſually ſeen of a green colour, when looked at from below, appeared to him of a very different one, caſting a redneſs upon one of his hands, like that of damaſk roſes Newton's Optic, p. 56. .—A proof of the ſea's taking its colour not from any thing floating in it, but from the different reflexions of the rays of light. Upon the whole, the accounts we have received from the bottom, by this contrivance, are but few. We learn from it, and from divers in general, that while the ſurface of the ſea may be deformed by tempeſts, it is uſually calm and temperate below Boyle, vol. iii. p. 242. ; that ſome divers who have gone down when the weather was calm, and came up when it was tempeſtuous, were ſurprized at their not perceiving the change at the bottom. This, however, muſt not be ſuppoſed to obtain with regard to the tides, and the currents, as they are ſeen conſtantly ſhifting their bottom; taking their bed with great violence from one place, and depoſiting it upon another. We are informed, alſo, by divers, that the ſea grows colder in proportion as they deſcend to the bottom; that as far as the ſun's rays pierce, it is influenced by their warmth; but lower, the cold becomes almoſt intolerable. A perſon of quality, who had been himſelf a diver, as Mr. Boyle informs us, declared, that though he ſeldom deſcended above three or four fathoms, yet he found it ſo much colder than near the top, that he could not well endure it; and that being let down in a great diving-bell, although the water could not immediately touch him, he found the air extremely cold upon his firſt arrival at the bottom.

From divers alſo we learn, that the ſea in many places is filled with rocks at bottom; and that among their clifts, and upon their ſides, various ſubſtances ſprout forward, which are either really vegetables, or the neſts of inſects, encreaſed to ſome magnitude. Some of theſe aſſume the ſhape of beautiful flowers; and, tho' ſoft, when taken up, ſoon harden, and are kept in the cabinets of the curious.

But, of all thoſe divers who have brought us information from the bottom of the deep, the famous Nicola Peſce, whoſe performances are told us by Kircher, is the moſt celebrated. I will not ſo much as pretend to vouch for the veracity of Kircher's account, which he aſſures us he had from the archives of the kings of Sicily; but it may ſerve to enliven an heavy chapter. "In the times of Frederic, king of Sicily, there lived a celebrated diver, whoſe name was Nicolas, and who, from his amazing ſkill in ſwimming, and his perſeverance under water, was ſurnamed the fiſh. This man had, from his infancy, been uſed to the ſea; and earned his ſcanty ſubſiſtence by diving for corals, and oyſters; which he ſold to the villages on ſhore. His long acquaintance with the ſea, at laſt, brought it to be almoſt his natural element. He frequently was known to ſpend five days in the midſt of the waves, without any other proviſions than the fiſh which he caught there, and ate raw. He often ſwam over from Sicily into Calabria, a tempeſtuous and dangerous paſſage, carrying letters from the king. He was frequently known to ſwim among the gulphs of the Lipari iſlands, no way apprehenſive of danger.

"Some mariners out at ſea one day obſerved ſomething at ſome diſtance from them, which they regarded as a ſea-monſter; but upon its approach, it was known to be Nicolas, whom they took into their ſhip. When they aſked him whither he was going in ſo ſtormy and rough a ſea, and at ſuch a diſtance from land, he ſhewed them a packet of letters, which he was carrying to one of the towns of Italy, exactly done up in a leather bag, in ſuch a manner as that they could not be wetted by the ſea. He kept them thus company for ſome time on their voyage, converſing, and aſking queſtions; and after eating an hearty meal with them, he took his leave, and jumping into the ſea, purſued his voyage alone.

"In order to aid theſe powers of enduring in the deep, nature ſeemed to have aſſiſted him in a very extraordinary manner; for the ſpaces between his fingers and toes were webbed, as in a gooſe; and his cheſt became ſo very capacious, that he could take in at one inſpiration, as much breath as would ſerve him for an whole day.

"The account of ſo extraordinary a perſon did not fail to reach the king himſelf; who, actuated by the general curioſity, ordered that Nicolas ſhould be brought before him. It was no eaſy matter to find Nicolas, who generally ſpent his time in the ſolitudes of the deep; but at laſt, however, after much ſearching, he was found, and brought before his majeſty. The curioſity of this monarch had been long excited by the accounts he had heard of the bottom of the gulph of Charybdis; he now, therefore, conceived that it would be a proper opportunity to have more certain information. He therefore commanded our poor diver to examine the bottom of this dreadful whirlpool; and, as an incitement to his obedience, ordered a golden cup to be flung into it. Nicolas was not inſenſible of the danger to which he was expoſed; dangers beſt known only to himſelf; and he therefore preſumed to remonſtrate: but the hopes of the reward, the deſire of pleaſing the king, and the pleaſure of ſhewing his ſkill, at laſt prevailed. He inſtantly jumped into the gulph, and was ſwallowed as inſtantly up in its boſom. He continued for three quarters of an hour below; during which time, the king and his attendants remained upon ſhore, anxious for his fate; but he at laſt appeared, buffeting upon the ſurface, holding the cup in triumph in one hand, and making his way good among the waves with the other. It may be ſuppoſed he was received with applauſe, upon his arrival on ſhore: the cup was made the reward of his adventure; the king ordered him to be taken proper care of; and, as he was ſomewhat fatigued and debilitated by his labour, after an hearty meal, he was put to bed, and permitted to refreſh himſelf by ſleeping.

"When his ſpirits were thus reſtored, he was again brought, to ſatisfy the king's curioſity with a narrative of the wonders he had ſeen; and his account was to the following effect. He would never, he ſaid, have obeyed the king's commands, had he been apprized of half the dangers that were before him. There were four things, he ſaid, that rendered the gulph dreadful, not only to men, but even to the fiſhes themſelves: firſt, the force of the water burſting up from the bottom, which require great ſtrength to reſiſt; ſecondly, the abruptneſs of the rocks, that on every ſide threatened deſtruction; thirdly, the force of the whirlpool, daſhing againſt thoſe rocks; and fourthly, the number and magnitude of the polypous fiſh, ſome of which appeared as large as a man, and which every where ſticking againſt the rocks, projected their fibrous arms to entangle him. Being aſked how he was able ſo readily to find the cup that had been thrown in, he replied, that it happened to be flung by the waves into the cavity of a rock, againſt which he himſelf was urged in his deſcent. This account, however, did not ſatisfy the king's curioſity: being requeſted to venture once more into the gulph for further diſcoveries, he at firſt refuſed; but the king, deſirous of having the moſt exact information poſſible of all things to be found in the gulph, repeated his ſollicitations; and, to give them ſtill greater weight, produced a larger cup than the former, and added alſo a purſe of gold. Upon theſe conſiderations, the unfortunate Peſſacola once again plunged into the whirlpool, and was never heard of more."

A Late eminent philoſopher has conſidered our atmoſphere as one large chymical veſſel, in which an infinite number of various operations are conſtantly performing. In it all the bodies of the earth are continually ſending up a part of their ſubſtance by evaporation, to mix in this great alembic, and to float a-while in common. Here minerals, from their loweſt depths, aſcend in noxious, or in warm vapours, to make a part of the general maſs; ſeas, rivers, and ſubterraneous ſprings, furniſh their copious ſupplies; plants receive and return their ſhare; and animals, that by living upon, conſume this general ſtore, are found to give it back in greater quantities, when they die Boyle, vol. ii. p. 593. . The air, therefore, that we breathe, and upon which we ſubſiſt, bears very little reſemblance to that pure elementary body which was deſcribed in the laſt chapter; and which is rather a ſubſtance that may be conceived, than experienced to exiſt. Air, ſuch as we find it, is one of the moſt compounded bodies in all nature. Water may be reduced to a fluid every way reſembling air, by heat; which, by cold, becomes water again. Every thing we ſee, gives off its parts to the air, and has a little floating atmoſphere of its own round it. The roſe is encompaſſed with a ſphere of its own odorous particles; while the night-ſhade infects the air with ſcents of a more ungrateful nature. The perfume of muſk flies off in ſuch abundance, that the quantity remaining, becomes ſenſibly lighter by the loſs. A thouſand ſubſtances that eſcape all our ſenſes, we know to be there; the powerful emanations of the load-ſtone, the effluvia of electricity, the rays of light, and the inſinuations of fire. Such are the various ſubſtances through which we move, and which we are conſtantly taking in at every pore, and returning again with imperceptible diſcharge.

This great ſolution, or mixture of all earthly bodies, is continually operating upon itſelf; which, perhaps, may be the cauſe of its unceaſing motion: but it operates ſtill more viſibly upon ſuch groſſer ſubſtances as are expoſed to its influence; for ſcarce any ſubſtance is found capable of reſiſting the corroding qualities of the air. The air, ſay the chymiſts, is a chaos, furniſhed with all kinds of ſalts and menſtruums; and, therefore, it is capable of diſſolving all kinds of bodies. It is well known, that copper and iron are quickly covered, and eaten with ruſt; and that in the climates near the equator, no art can keep them clean. In thoſe dreary countries, the inſtruments, knives and keys, that are kept in the pocket, nevertheleſs are quickly encruſted; and the great guns, with every precaution, after ſome years, become uſeleſs. Stones, as being leſs hard, may be readily ſuppoſed to be more eaſily ſoluble. The marble of which the noble monuments of Italian antiquity are compoſed, although in one of the fineſt climates in the world, nevertheleſs ſhew the impreſſions which have been made upon them by the air. In many places they ſeem worm-eaten by time; and, in others, they appear crumbling into duſt. Gold alone ſeems to be exempted from this general ſtate of diſſolution; it is never found to contract ruſt, though expoſed never ſo long: the reaſon of this ſeems to be, that ſea-ſalt, which is the only menſtruum capable of acting upon, and diſſolving gold, is but very little mixed with the air; for ſalt being a very fixed body, and not apt to volatilize, and riſe with heat, there is but a ſmall proportion of it in the atmoſphere. In the elaboratories, and ſhops, however, where ſalt is much uſed, and the air is impregnated with it, gold is found to ruſt as well as other metals.

Bodies of a ſofter nature are obviouſly deſtroyed by the air Buffon, vol. iii. p. 62. . Mr. Boyle ſays, that ſilks brought to Jamaica, will, if there expoſed to the air, rot even while they preſerve their colour; but if kept therefrom, they both retain their ſtrength and gloſs. The ſame happens in Braſil, where their cloaths, which are black, ſoon turn of an iron colour; though, in the ſhops, they preſerve their proper hue Ibid, vol. iii. p. 68. . In theſe tropical climates alſo, ſuch are the putreſcent qualities of the air, that white ſugar will ſometimes be full of maggots. Drugs and plaiſters loſe their virtue, and become verminous. In ſome places they are obliged to expoſe their ſweetmeats by day in the ſun, otherwiſe the night air would quickly cauſe them to putrefy. On the contrary, in the cold arctic regions, animal ſubſtances, during their winter, are never known to putrefy; and meat may be kept for months, without any ſalt whatſoever. This experiment happily ſucceeded with the eight Engliſhmen that were accidentally left upon the inhoſpitable coaſts of Greenland, at a place where ſeven Dutchmen had periſhed but a few years before; for killing ſome rein-deer for their ſubſiſtence, and having no ſalt to preſerve the fleſh, to their great ſurprize, they ſoon found it did not want any, as it remained ſweet during their eight months continuance upon that ſhore.

Theſe powers with which air is endued over unorganized ſubſtances, are exerted in a ſtill ſtronger manner over plants, animals of an inferior nature, and, laſtly, over man himſelf. Moſt of the beauty, and the luxuriance of vegetation, is well known to be derived from the benign influence of the air: and every plant ſeems to have its favourite climate, not leſs than its proper ſoil. The lower ranks of animals alſo, ſeem formed for their reſpective climates, in which only they can live. Man alone ſeems the child of every climate, and capable of exiſting in all. However, this peculiar privilege does not exempt him from the influences of the air; he is as much ſubject to its malignity, as the meaneſt inſect or vegetable.

With regard to plants, air is ſo abſolutely neceſſary for their life and preſervation, that they will not vegetate in an exhauſted receiver. All plants have within them a quantity of air, which ſupports and agitates their juices. They are continually imbibing freſh nutriment from the air, to encreaſe this ſtore, and to ſupply the wants which they ſuſtain from evaporation. When, therefore, the external air is drawn from them, they are no longer able to ſubſiſt. Even that quantity of air which they before were poſſeſſed of, eſcapes through their pores, into the exhauſted receiver; and as this continues to be pumped away, they become languid, grow flaccid, and die. However, the plant or flower thus ceaſing to vegetate, is kept, by being ſecured from the external air, a much longer time ſweet than it would have continued, had it been openly expoſed.

That air which is ſo neceſſary to the life of vegetables, is ſtill more ſo to that of animals; there are none found, how ſeemingly torpid ſoever, that do not require their needful ſupply. Fiſhes themſelves will not live in water from whence the air is exhauſted; and it is generally ſuppoſed that they die in frozen ponds, from the want of this neceſſary to animal exiſtence. Many have been the animals that idle curioſity has tortured in the priſon of a receiver, merely to obſerve the manner of their dying. We ſhall, from a thouſand inſtances, produce that of the viper, as it is known to be one of the moſt vivacious reptiles in the world; and as we ſhall feel but little compaſſion for its tortures. Mr. Boyle took a new caught viper, and ſhutting it up into a ſmall receiver, began to pump away the air Boyle's Phico. Mechan. Exper. Paſſim. . "At firſt, upon the air's being drawn away, it began to ſwell; ſome time after he had done pumping, it began to gape, and open its jaws; being thus compelled to open its jaws, it once more reſumed its former lankneſs; it then began to move up and down within, as if to ſeek for air, and after a while foamed a little, leaving the foam ſticking to the inſide of the glaſs; ſoon after the body and neck grew prodigiouſly tumid, and a bliſter appeared upon its back; an hour and an half after the receiver was exhauſted, the diſtended viper moved, and gave manifeſt ſigns of life; the jaws remained quite diſtended; as it were from beneath the epiglottis, came the black tongue, and reached beyond it; but the animal ſeemed, by its poſture, not to have any life: the mouth alſo was grown blackiſh within; and in this ſituation it continued for twenty-three hours. But upon the air's being re-admitted, the viper's mouth was preſently cloſed, and ſoon after opened again; and for ſome time thoſe motions continued, which argued the remains of life." Such is the fate of the moſt inſignificant or minute reptile that can be thus included. Mites, fleas, and even the little eels that are found ſwimming in vinegar, die for want of air. Not only theſe, but the eggs of theſe animals, will not produce in vacuo, but require air to bring them to perfection.

As in this manner air is neceſſary to their ſubſiſtence, ſo alſo it muſt be of a proper kind, and not impregnated with foreign mixtures. That factitious air which is pumped from plants or fluids, is generally, in a ſhort time, fatal to them. Mr. Boyle has given us many experiments to this purpoſe. After having ſhewn that all vegetable, and moſt mineral ſubſtances, properly prepared, may afford air, by being placed in an exhauſted receiver, and this in ſuch quantities, that ſome have thought it a new ſubſtance, made by the alteration which the mineral or plant has undergone by the texture of its parts being looſened in the operation—having ſhewn, I ſay, that this air may be drawn in great quantities from vegetable, animal, or mineral ſubſtances, ſuch as apples, cherries, amber burnt, or hartſhorn Boyle's Phyſic. Mechan. vol. ii. p. 598. —he included a frog in artificial air, produced from paſte; in ſeven minutes ſpace it ſuffered convulſions, and at laſt lay ſtill, and being taken out, recovered no motion at all, but was dead. A bird encloſed in artificial air, from raiſins, died in a quarter of a minute, and never ſtirred more. A ſnail was put into the receiver, with air of paſte; in four minutes it ceaſed to move, and was dead, altho' it had ſurvived in vacuo for ſeveral hours: ſo that factitious air proved a greater enemy to animals than even a vacuum itſelf.

Air alſo may be impregnated with fumes that are inſtantly fatal to animals. The fumes of hot iron, copper, or any other heated metal, blown into the place where an animal is confined, inſtantly deſtroy it. We have already mentioned the vapours in the grotto Del Cane ſuffocating a dog. The ancients even ſuppoſed, that theſe animals, as they always ran with their noſes to the ground, were the firſt that felt any infection. In ſhort, it ſhould ſeem that the predominance of any one vapour, from any body, how wholſome ſoever in itſelf, becomes infectious; and that we owe the ſalubrity of the air to the variety of its mixture.

But there is no animal whoſe frame is more ſenſibly affected by the changes of the air than man. It is true, he can endure a greater variety of climates than the lower orders generally are able to do; but it is rather by the means which he has diſcovered of obviating their effects, than by the apparent ſtrength of his conſtitution. Moſt other animals can bear cold or hunger better, endure greater fatigues in proportion, and are ſatisfied with ſhorter repoſe. The variations of the climate, therefore, would probably affect them leſs, if they had the ſame means or ſkill in providing againſt the ſeverities of the change. However this be, the body of man is an inſtrument much more nicely ſenſible of the variations of the air, than any of thoſe which his own art has produced; for his frame alone ſeems to unite all their properties, being invigorated by the weight of the air, relaxed by its moiſture, enfeebled by its heat, and ſtiffened by its frigidity.

But it is chiefly by the predominance of ſome peculiar vapour, that the air becomes unfit for human ſupport. It is often found, by dreadful experience, to enter into the conſtitution, to mix with its juices, and to putrefy the whole maſs of blood. The nervous ſyſtem is not leſs affected by its operations; palſies and vertigoes are cauſed by its damps; and a ſtill more fatal train of diſtempers by its exhalations. In order that the air ſhould be wholeſome, it is neceſſary, as we have ſeen, that it ſhould not be of one kind, but the compound of ſeveral ſubſtances; and the more various the compoſition, to all appearance the more ſalubrious. A man, therefore, who continues in one place, is not ſo likely to enjoy this wholeſome variety, as he who changes his ſituation; and, if I may ſo expreſs it, inſtead of waiting for a renovation of air, walks forward to meet its arrival. Thus mere motion, independent even of the benefits of exerciſe, becomes wholſome, by thus ſupplying a greater variety of that healthful fluid by which we are ſuſtained.

A thouſand accidents are found to encreaſe theſe bodies of vapour, that make one place more or leſs wholſome than another. Heat may raiſe them in too great quantities; and cold may ſtagnate them. Minerals may give off their effluvia in ſuch proportion as to keep away all other kind of air; vegetables may render the air unwholſome by their ſupply; and animal putrefaction ſeems to furniſh a quantity of vapour, at leaſt as noxious as any of the former. All theſe united, generally make up the maſs of reſpiration, and are, when mixed together, harmleſs; but any one of them, for a long time ſingly predominant, becomes at length fatal.

The effects of heat in producing a noxious quality in the air, are well known. Thoſe torrid regions under the Line are always unwholſome. At Senegal, I am told, the natives conſider forty as a very advanced time of life, and generally die of old age at fifty. At Carthagena Ulloa, vol. i. p. 42. , in America, where the heat of the hotteſt day ever known in Europe is continual, where, during their winter ſeaſon, theſe dreadful heats are united with a continual ſucceſſion of thunder, rain, and tempeſts, ariſing from their intenſeneſs, the wan and livid complexions of the inhabitants might make ſtrangers ſuſpect that they were juſt recovered from ſome dreadful diſtemper; the actions of the natives are conformable to their colour; in all their motions there is ſomewhat relaxed and languid; the heat of the climate even affects their ſpeech, which is ſoft and ſlow, and their words generally broken. Travellers from Europe retain their ſtrength and ruddy colour in that climate, poſſibly for three or four months; but afterwards ſuffer ſuch decays in both, that they are no longer to be diſtinguiſhed from the inhabitants by their complexion. However, this languid and ſpiritleſs exiſtence is frequently drawled on ſometimes even to eighty. Young perſons are generally moſt affected by the heat of climate, which ſpares the more aged; but all, upon their arrival on the coaſts, are ſubject to the ſame train of fatal diſorders. Few nations have experienced the mortality of theſe coaſts, ſo much as our own: in our unſucceſsful attack upon Carthagena, more than three parts of our army were deſtroyed by the climate alone; and thoſe that returned from that fatal expedition, found their former vigour irretrievably gone. In our more fortunate expedition, which gave us the Havannah, we had little reaſon to boaſt of our ſucceſs; inſtead of a third, not a fifth part of the army were left ſurvivors of their victory, the climate being an enemy that even heroes cannot conquer.

The diſtempers that thus proceed from the cruel malignity of thoſe climates, are many: that, for inſtance, called the Chapotonadas, carries off a multitude of people; and extremely thins the crews of European ſhips, whom gain tempts into thoſe inhoſpitable regions. The nature of this diſtemper is but little known, being cauſed in ſome perſons by cold, in others by indigeſtion. But its effects are far from being obſcure; it is generally fatal in three or four days: upon its ſeizing the patient, it brings on what is there called the black vomit, which is the ſad ſymptom after which none are ever found to recover. Some, when the vomit attacks them, are ſeized with a delirium, that, were they not tied down, they would tear themſelves to pieces, and thus expire in the midſt of this furious paroxyſm. This diſorder, in milder climates, takes the name of the bilious fever, and is attended with milder ſymptoms, but very dangerous in all.

There are many other diſorders incident to the human body, that ſeem the offspring of heat; but to mention no other, that very laſſitude which prevails in all the tropical climates, may be conſidered as a diſeaſe. The inhabitants of India Linnaei Amonitates, vol. v. p 444. , ſays a modern philoſopher, ſuſtain an unceaſing languor, from the heats of their climate; and are torpid in the midſt of profuſion. For this reaſon, the great Diſpoſer of Nature has cloathed their country with trees of an amazing height, whoſe ſhade might defend them from the beams of the ſun; and whoſe continual freſhneſs might, in ſome meaſure, temperate their fierceneſs. From theſe ſhades, therefore, the air receives refreſhing moiſture, and animals a cooling protection. The whole race of ſavage animals retire, in the midſt of the day, to the very center of the foreſts, not ſo much to avoid their enemy man, as to find a defence againſt the raging heats of the ſeaſon. This advantage which ariſes from ſhade in torrid climates, may probably afford a ſolution for that extraordinary circumſtance related by Boyle, which he imputes to a different cauſe. In the iſland of Ternate, belonging to the Dutch, a place that had been long celebrated for its beauty and healthfulneſs, the clove trees grew in ſuch plenty, that they in ſome meaſure leſſened their own value: for this reaſon, the Dutch reſolved to cut down the foreſts, and thus to raiſe the price of the commodity: but they had ſoon reaſon to repent of their avarice; for ſuch a change enſued, by cutting down the trees, that the whole iſland, from being healthy and delightful, having loft its charming ſhades, became extremely ſickly, and has actually continued ſo to this day. Boerhaave conſidered heat ſo prejudicial to health, that he was never ſeen to go near a fire.

An oppoſite ſet of calamities are the conſequence, in climates where the air is condenſed by cold. In ſuch places, all that train of diſtempers which are known to ariſe from obſtructed perſpiration, are very common Krantz's Hiſtory of Greenland, vol. i. p. 235. ; eruptions, boils, ſcurvy, and a loathſome leproſy, that covers the whole body with a ſcurf, and white putrid ulcers. Theſe diſorders alſo, are infectious; and, while they thus baniſh the patient from ſociety, they generally accompany him to the grave. The men of thoſe climates ſeldom attain to the age of fifty; but the women, who do not lead ſuch laborious lives, are found to live longer.

The autumnal complaints which attend a wet ſummer, indicate the dangers of a moiſt air. The long continuance of an eaſt wind alſo, ſhews the prejudice of a dry one. Mineral exhalations, when copious, are every where known to be fatal; and although we probably owe the encreaſe and luxuriance of vegetation to a moderate degree of their warmth, yet the natives of thoſe countries where there are mines in plenty, but too often experience the noxious effects of their vicinity. Thoſe trades alſo that deal in the preparations of metals of all kinds, are always unwholſome; and the workmen, after ſome time, are generally ſeen to labour under palſies, and other nervous complaints. The vapours from ſome vegetable ſubſtances, are well known to be attended with dangerous effects. The ſhade of the machinel tree, in America, is ſaid to be fatal; as was that of the juniper, if we may credit the ancients. Thoſe who walk through fields of poppies, or in any manner prepare thoſe flowers for making opium, are very ſenſibly affected with the drowſineſs they occaſion. A phyſician of Mr. Boyle's acquaintance, cauſing a large quantity of black hellebore to be pounded in a mortar, moſt of the perſons who were in the room, and eſpecially the perſon who pounded it, were purged by it, and ſome of them ſtrongly. He alſo gathered a certain plant in Ireland, which the perſon who beat in a mortar, and the phyſician who was ſtanding near, were ſo ſtrongly affected by, that their hands and faces ſwelled to an enormous ſize, and continued tumid for a long time after.

But neither mineral nor vegetable ſteams are ſo dangerous to the conſtitution, as thoſe proceeding from animal ſubſtances, putrefying either by diſeaſe or death. The effluvia that comes from diſeaſed bodies, propagate that frightful catalogue of diſorders which are called infectious. The parts which compoſe vegetable vapours, and mineral exhalations, ſeem groſs and heavy, in compariſon of theſe volatile vapours, that go to great diſtances, and have been deſcribed as ſpreading deſolation over the whole earth. They fly every where; penetrate every where; and the vapours that fly from a ſingle diſeaſe, ſoon render it epidemic.

The plague is the firſt upon the liſt in this claſs of human calamities. From whence this ſcourge of man's preſumption may have its beginning, is not well known; but we well know that it is propagated by infection. Whatever be the general ſtate of the atmoſphere, we learn, from experience, that the noxious vapours, though but ſingly introduced at firſt, taints the air by degrees: every perſon infected, tends to add to the growing malignity; and, as the diſorder becomes more general, the putreſcence of the air becomes more noxious, ſo that the ſymptoms are aggravated by continuance. When it is ſaid that the origin of this diſorder is unknown, it implies, that the air ſeems to be but little employed in firſt producing it. There are ſome countries, even in the midſt of Africa, that we learn have never been inſected with it; but continue, for centuries, unmoleſted. On the contrary, there are others, that are generally viſited once a year, as in Egypt, which, nevertheleſs, ſeems peculiarly bleſſed with the ſerenity and temperature of its climate. In the former countries, which are of vaſt extent, and many of them very populous, every thing ſhould ſeem to diſpoſe the air to make the plague continual among them. The great heats of the climate, the unwholſomeneſs of the food, the ſloth and dirt of the inhabitants, but, above all, the bloody battles which are continually fought among them, after which heaps of dead bodies are left unburied, and expoſed to putrefaction. All theſe one might think would be apt to bring the plague among them; and yet, nevertheleſs, we are aſſured by Leo Africanus, that in Numidia the plague is not known once in an hundred years; and that in Negroland, it is not known at all. This dreadful diſorder, therefore, muſt have its riſe, not from any previous diſpoſition of the air, but from ſome particular cauſe, beginning with one individual, and extending the malignity, by communication, till at laſt the air becomes actually tainted by the generality of the infection.

The plague which ſpread itſelf over the whole world, in the year 1346, as we are told by Mezeray, was ſo contagious, that ſcarce a village, or even an houſe, eſcaped being infected by it. Before it had reached Europe, it had been for two years travelling from the great kingdom of Cathay, where it began by a vapour moſt horridly fetid; this broke out of the earth like a ſubterranean fire, and upon the firſt inſtant of its eruption, conſumed and deſolated above two hundred leagues of that country, even to the trees and ſtones.

In that great plague which deſolated the city of London, in the year 1665, a pious and learned ſchoolmaſter of Mr. Boyle's acquaintance, who ventured to ſtay in the city, and took upon him the humane office of viſiting the ſick and the dying, who had been deſerted by better phyſicians, averred, that being once called to a poor woman who had buried her children of the plague, he found the room where ſhe lay ſo little that it ſcarce could hold any more than the bed whereon ſhe was ſtretched. However, in this wretched abode, beſide her, in an open coffin, her huſband lay, who had ſome time before died of the ſame diſeaſe; and whom ſhe, poor creature, ſoon followed. But what ſhewed the peculiar malignity of the air thus ſuffering from animal putrefaction, was, that the contagious ſteams had produced ſpots on the very wall of their wretched apartment: and Mr. Boyle's own ſtudy, which was contiguous to a peſt-houſe, was alſo ſpotted in the ſame frightful manner. Happily for mankind, this diſorder, for more than a century, has not been known in our iſland; and, for this laſt age, has abated much of its violence, even in thoſe countries where it is moſt common. Diſeaſes, like empires, have their revolutions; and thoſe which for a while were the ſcourge of mankind, ſink unheard of, to give place to new ones, more dreadful, as being leſs underſtood.

For this revolution in diſorders, which has employed the ſpeculation of many, Mr. Boyle accounts in the following manner. "Since," ſays he, "there want not cauſes in the bowels of the earth, to make conſiderable changes amongſt the materials that nature has plentifully treaſured up in thoſe magazines, and as thoſe noxious ſteams are abundantly ſupplied to the ſurface, it may not ſeem improbable, that in this great variety, ſome may be found capable of particularly affecting the human frame in a particular manner, and thus of producing new diſeaſes. The duration of theſe may be greater or leſs, according to the laſtingneſs of thoſe ſubterraneous cauſes that produced them. On which account, it need be no wonder that ſome diſeaſes have but a ſhort duration, and vaniſh not long after they appear; whilſt others may continue longer, as having under ground more ſettled and durable cauſes to maintain them."

From the recital of this train of miſchiefs produced by the air, upon minerals, plants, animals, and man himſelf, a gloomy mind may be apt to dread this indulgent nurſe of nature as a cruel and an inexorable ſtep-mother: but it is far otherwiſe; and, although we are ſometimes injured, yet almoſt all the comforts and bleſſings of life ſpring from its propitious influence. It would be needleſs to obſerve, that it is abſolutely neceſſary for the ſupport of our lives; for of this, every moment's experience aſſures us. But how it contributes to this ſupport, is not ſo readily comprehended. All allow it to be a friend, to whoſe benefits we are conſtantly obliged: and yet, to this hour, philoſophers are divided as to the nature of the obligation. The diſpute is, whether the air is only uſeful by its weight to force our juices into circulation Keil. Robinſon. ; or, whether, by containing a peculiar ſpirit, it mixes with the blood in our veſſels, and acts like a ſpur to their induſtry Whytt upon vital and involuntary Motions. . Perhaps it may exert both theſe uſeful offices at the ſame time. Its weight may give the blood its progreſſive motion, through the larger veſſels of the body; and its admixture with it, cauſe thoſe contractions of all the veſſels, which ſerve to force it ſtill more ſtrongly forward, through the minuteſt channels of the circulation. Be this as it may, it is well known, that that part of our blood which has juſt received the influx of the air in our bodies, is of a very different colour from that which has almoſt performed its circuit. It has been found, that the arterial blood which has been immediately mixed with the air in the lungs, and, if I may ſo expreſs it, is juſt beginning its journey through the body, is of a fine florid ſcarlet colour; while, on the contrary, the blood of the veins that is returning from having performed its duty, is of a blackiſh crimſon hue. Whence this difference of colour ſhould proceed, is not well underſtood: we only know the fact, that this florid colour is communicated by the air; and we are well convinced, that this air has been admitted into the blood for very uſeful purpoſes.

Beſides this vital principle in animals, the air alſo gives life and body to flame. A candle quickly goes out in an exhauſted receiver; for having ſoon conſumed the quantity of air, it then expires, for want of a freſh ſupply. There has been a flame contrived that will burn under water; but none yet has been found, that will continue to burn without air. Gunpowder, which is the moſt catching and powerful fire we know, will not go off in an exhauſted receiver; nay, if a train of gunpowder be laid, ſo as that one part may be fired in the open air, yet the other part in vacuo will remain untouched, and unconſumed. Wood alſo ſet on fire, immediately goes out; and its flame ceaſes upon removing the air; for ſomething is then wanting to preſs the body of the fire againſt that of the fuel, and to prevent the too ſpeedy diffuſion of the flame. We frequently ſee cooks, and others, whoſe buſineſs it is to keep up ſtrong fires, take proper precautions to exclude the beams of the ſun from ſhining upon them, which effectually puts them out. This they are apt to aſcribe to a wrong cauſe; namely, the operation of the light: but the real fact is, that the warmth of the ſun-beams leſſen and diſſipate the body of the air that goes to feed the flame; and the fire, of conſequence, languiſhes for want of a neceſſary ſupply.

The air, while it thus kindles fire into flame, is notwithſtanding found to moderate the rays of light, to diſſipate their violence, and to ſpread an uniform luſtre over every object. Were the beams of the ſun to dart directly upon us, without paſſing through this protecting medium, they would either burn us up at once, or blind us with their effulgence. But by going through the air, they are reflected, refracted, and turned from their direct courſe, a thouſand different ways; and thus are more evenly diffuſed over the face of nature.

Among the other neceſſary benefits the air is of to us, one of the principal is its conveyance of ſound. Even the vibrations of a bell, which have the loudeſt effect that we know of, ceaſes to be heard, when under the receiver of an air-pump. Thus all the pleaſures we receive from converſation with each other, or from muſic, depend entirely upon the air.

Odours likewiſe are diffuſed only by the means of air; without this fluid to ſwim in, they would for ever remain torpid in their reſpective ſubſtances; and the roſe would affect us with as little ſenſations of pleaſure, as the thorn on which it grew.

Thoſe who are willing to augment the catalogue of the benefits we receive from this element, aſſert alſo, that taſtes themſelves would be inſipid, were it not that the air preſſes their parts upon the nerves of the tongue and palate, ſo as to produce their grateful effects. Thus, continue they, upon the tops of high mountains, as on the Pike of Teneriff, the moſt poignant bodies, as pepper, ginger, ſalt, and ſpice, have no ſenſible taſte, for want of their particles being thus ſent home to the ſenſory. But, we owe the air ſufficient obligations, not to be ſtudious of admitting this among the number: in fact, all ſubſtances have their taſtes, as well on the tops of mountains, as in the bottom of the valley; and I have been one of many, who have ate a very ſavoury dinner on the Alps.

It is ſufficient, therefore, that we regard the air as the parent of health and vegetation; as a kind diſpenſer of light and warmth; and as the conveyer of ſounds and odours. This is an element of which avarice will not deprive us; and which power cannot monopolize. The treaſures of the earth, the verdure of the fields, and even the refreſhments of the ſtream, are too often ſeen going only to aſſiſt the luxuries of the great; while the leſs fortunate part of mankind ſtand humble ſpectators of their encroachments. But the air no limitations can bound, nor any land-marks reſtrain. In this benign element, all mankind can boaſt an equal poſſeſſion; and for this we all have equal obligations to Heaven. We conſume a part of it, for our own ſuſtenance, while we live; and, when we die, our putrefying bodies give back the ſupply, which, during life, we had accumulated from the general maſs.

WIND is a current of air. Experimental philoſophers produce an artificial wind, by an inſtrument called an aeolipile. This is nothing more than an hollow copper ball, with a long pipe; a tea kettle might be readily made into one, if it were entirely cloſed at the lid, and the ſpout left open; through this ſpout it is to be filled with water, and then ſet upon the fire, by which means it produces a violent blaſt, like wind, which continues while there is any water remaining in the inſtrument. In this manner water is converted into a ruſhing air; which, if caught as it goes out, and left to cool, is again quickly converted into its former element. Beſides this, as was mentioned in the former chapter, almoſt every ſubſtance contains ſome portions of air. Vegetables, or the bodies of animals left to putrefy, produce it in a very copious manner. But it is not only ſeen thus eſcaping from bodies, but it may be very eaſily made to enter into them. A quantity of air may be compreſſed into water, ſo as to be intimately blended with it. It finds a much eaſier admiſſion into wine, or any fermented liquor; and an eaſier ſtill, into ſpirits of wine. Some ſalts ſuck up the air in ſuch quantities, that they are made ſenſibly heavier thereby, and often are melted by its moiſture. In this manner, moſt bodies, being found either capable of receiving or affording it, we are not to be ſurprized at thoſe ſtreams of air that are continually fleeting round the globe. Minerals, vegetables, and animals, contribute to encreaſe the current; and are ſending off their conſtant ſupplies. Theſe, as they are differently affected by cold or heat, by mixture or putrefaction, all yield different quantities of air at different times; and the loudeſt tempeſts, and moſt rapid whirlwinds, are formed from their united contributions.

The ſun is the principal inſtrument in rarefying the juices of plants, ſo as to give an eſcape to their impriſoned air; it is alſo equally operative in promoting the putrefaction of animals. Mineral exhalations are more frequently raiſed by ſubterranean heat. The moon, the other planets, the ſeaſons, are all combined in producing theſe effects in a ſmaller degree. Mountains give a direction to the courſes of the air. Fires carry a current of air along their body. Night and day alternately chill and warm the earth, and produce an alternate current of its vapours. Theſe, and an hundred other cauſes, may be aſſigned for the variety, and the activity of the winds, their continual change, and uncertain duration.

With us on land, therefore, as the wind proceeds from ſo many cauſes, and meets ſuch a variety of obſtacles, there can be but little hopes of ever bringing its motions to conform to theory; or of foretelling how it may blow a minute to come. The great Bacon, indeed, was of opinion, that by a cloſe and regular hiſtory of the winds, continued for a number of ages together, and the particulars of each obſervation reduced to general maxims, we might at laſt come to underſtand the variations of this capricious element; and that we could foretell the certainty of a wind, with as much eaſe as we now foretell the return of an eclipſe. Indeed, his own beginnings in this arduous undertaking, ſeem to ſpeak the poſſibility of its ſucceſs; but, unhappily for mankind, this inveſtigation is the work of ages, and we want a Bacon to direct the proceſs.

To be able, therefore, with any plauſibility, to account for the variations of the wind upon land, is not to be at preſent expected; and to underſtand any thing of their nature, we muſt have recourſe to thoſe places where they are more permanent and ſteady. This uniformity and ſteadineſs we are chiefly to expect upon the ocean. There, where there is no variety of ſubſtances to furniſh the air with various and inconſtant ſupplies, where there are no mountains to direct the courſe of its current, but where all is extenſively uniform and even; in ſuch a place, the wind ariſing from a ſimple cauſe, muſt have but one ſimple motion. In fact, we find it ſo. There are many parts of the world where the winds, that with us are ſo uncertain, pay their ſtated viſits. In ſome places, they are found to blow one way by day, and another by night; in others, for one half of the year, they go in a direction contrary to their former courſe: but what is more extraordinary ſtill, there are ſome places where the winds never change, but for ever blow the ſame way. This is particularly found to obtain between the tropics in the Atlantic and Aethiopic oceans; as well as in the great Pacific ſea.

Few things ſurely can appear more extraordinary to a perſon who has never been out of our variable latitudes, than this ſteady wind, that for ever ſits in the ſail, ſending the veſſel forward; and as effectually preventing its return. He who has been taught to conſider that nothing in the world is ſo variable as the winds, muſt certainly be ſurprized to find a place where there is nothing more uniform. With us their inconſtancy has become a proverb; with the natives of thoſe diſtant climates, they may talk of a friend or a miſtreſs as fixed and unchangeable as the winds, and mean a compliment by the compariſon. When our ſhips are once arrived into the proper latitudes of the great Pacific ocean, the mariner forgets the helm, and his ſkill becomes almoſt uſeleſs: neither ſtorms nor tempeſts are known to deform the glaſſy boſom of that immenſe ſheet of waters; a gentle breeze, that for ever blows in the ſame direction, reſts upon the canvas, and ſpeeds the navigator. In the ſpace of ſix weeks, ſhips are thus known to croſs an immenſe ocean, that takes more than ſo many months to return. Upon returning, the trade-wind, which has been propitious, is then avoided; the mariner is generally obliged to ſteer into the northern latitudes, and to take the advantage of every caſual wind that offers, to aſſiſt him into port. This wind, which blows with ſuch conſtancy one way, is known to prevail not only in the Pacific ocean, but alſo in the Atlantic, between the coaſts of Guinea and Brazil; and, likewiſe, in the Aethiopic ocean. This ſeems to be the great univerſal wind, blowing from the eaſt to the weſt, that prevails in all the extenſive oceans where the land does not frequently break the general current. Were the whole ſurface of the globe an ocean, there would probably be but this one wind, for ever blowing from the eaſt, and purſuing the motions of the ſun weſtward. All the other winds ſeem ſubordinate to this; and many of them are made from the deviations of its current. To form, therefore, any conception relative to the variations of the wind in general, it is fitteſt to begin with that which never varies.

There have been many theories to explain this invariable motion of the winds; among the reſt, we cannot omit that of Doctor Lyſter, for its ſtrangeneſs. "The ſea," ſays he, "in thoſe latitudes, is generally covered over with green weeds, for a great extent; and the air produced from the vegetable perſpiration of theſe, produces the trade-wind." The theory of Carteſius was not quite ſo abſurd. He alledged, that the earth went round faſter than its atmoſphere at the equator; ſo that its motion, from weſt to eaſt, gave the atmoſphere an imaginary one from eaſt to weſt; and thus an eaſt-wind was eternally ſeen to prevail. Rejecting thoſe arbitrary opinions, conceived without force, and aſſerted without proof, Doctor Halley has given one more plauſible; which ſeems to be the reigning ſyſtem of the day.

To conceive his opinion clearly, let us for a moment ſuppoſe the whole ſurface of the earth to be an ocean, and the air encompaſſing it on every ſide, without motion. Now it is evident, that that part of the air that lies directly under the beams of the ſun, will be rarefied; and if the ſun remained for ever in the ſame place, there would be a great vacuity in the air, if I may ſo expreſs it, beneath the place where the ſun ſtood. But the ſun moving forward, from eaſt to weſt, this vacuity will follow too, and ſtill be made under it. But while it goes on to make new vacuities, the air will ruſh in to fill up thoſe the ſun has already made; in other words, as it is ſtill travelling forward, the air will continually be ruſhing in behind, and purſue its motions from eaſt to weſt. In this manner, the air is put into motion by day; and by night, the parts continue to impel each other, till the next return of the ſun, that gives a new force to the circulation.

In this manner is explained the conſtant eaſt-wind that is found blowing round the globe, near the equator. But it is alſo known, that as we recede from the equator on either ſide, we come into a trade-wind, that continually blows from the poles, from the north on one ſide, or the ſouth on the other, both directing towards the equator. This alſo proceeds from a ſimilar cauſe with the former; for the air being more rarefied in thoſe places over which the ſun more directly darts its rays, the currents will come both from the north and the ſouth, to fill up the intermediate vacuity.

Theſe two motions, namely, the general one from eaſt to weſt, and the more particular one from both the Poles, will account for all the phaenomena of trade-winds; which, if the whole ſurface of the globe were ſea, would undoubtedly be conſtant, and for ever continue to blow in one direction. But there are a thouſand circumſtances to break theſe air-currents into ſmaller ones; to drive them back againſt their general courſe; to raiſe or depreſs them; to condenſe them into ſtorms; or to whirl them in eddies. In conſequence of this, regard muſt be often had to the nature of the ſoil, the poſition of the high mountains, the courſe of the rivers, and even to the luxuriance of vegetation.

If a country lying directly under the ſun, be very flat and ſandy, and if the land be low and extenſive, the heats occaſioned by the reflection of the ſun-beams, produces a very great rarefaction of the air. The deſarts of Africa, which are conformable to this deſcription, are ſcarce ever fanned by a breath of wind by day; but the burning ſun is continually ſeen blazing in intolerable ſplendor above them. For this reaſon, all along the coaſts of Guinea, the wind is always perceived blowing in upon land, in order to fill up the vacuity cauſed by the ſun's operation. In thoſe ſhores, therefore, the wind blows in a contrary direction to that of its general current; and is conſtantly found ſetting in from the weſt.

From the ſame cauſe it happens, that thoſe conſtant calms, attended with deluges of rain, are found in the ſame part of the ocean. For this tract being placed in the middle, between the weſterly winds blowing on the coaſt of Guinea, and the eaſterly trade-winds that move at ſome diſtance from ſhore, in a contrary direction, the tendency of that part of the air that lies between theſe two oppoſite currents, is indifferent to either, and ſo reſts between both in torpid ſerenity; and the weight of the incumbent atmoſphere, being diminiſhed by the continual contrary winds blowing from hence, it is unable to keep the vapours ſuſpended that are copiouſly borne thither; ſo that they fall in continual rains.

But it is not to be ſuppoſed, that any theory can account for all the phaenomena of even thoſe winds that are known to be moſt regular. Inſtead, therefore, of a complete ſyſtem of the trade-winds, we muſt rather be content with an imperfect hiſtory. Theſe Buffon, vol. ii. p. 230. , as was ſaid, being the reſult of a combination of effects, aſſume as great a variety as the cauſes producing them are various.

Beſides the great general wind abovementioned, in thoſe parts of the Atlantic that lie under the temperate zone, a north wind prevails conſtantly during the months of October, November, December, and January. Theſe, therefore, are the moſt favourable months for embarking for the Eaſt-Indies, in order to take the benefit of theſe winds, for croſſing the line: and it has been often found, by experience, that thoſe who had ſet ſail five months before, were not in the leaſt farther advanced in their voyage, than thoſe who waited for the favourable wind. During the winter of Nova Zembla, and the other arctic countries, a north wind reigns almoſt continually. In the Cape de Verde iſlands, a ſouth wind prevails during the month of July. At the Cape of Good Hope, a north-weſt wind blows during the month of September. There are alſo regular winds, produced by various cauſes, upon land. The ancient Greeks were the firſt who obſerved a conſtant breeze, produced by the melting of the ſnows, in ſome high neighbouring countries. This was perceived in Greece, Thrace, Macedonia, and the Aegean ſea. The ſame kind of winds are now remarked in the kingdom of Congo, and the moſt ſouthern parts of Africa. The flux and reflux of the ſea alſo produces ſome regular winds, that ſerve the purpoſes of trade; and, in general, it may be obſerved, that wherever there is a ſtrong current of water, there is a current of air that ſeems to attend it.

Beſide theſe winds that are found to blow in one direction, there are, as was ſaid before, others that blow for certain months of the year one way, and the reſt of the year the contrary way: theſe are called the Monſoons, from a famous pilot of that name, who firſt uſed them in navigation with ſucceſs Varenii Geographia Geurculis, cap. 20. . In all that part of the ocean that lies between Africa and India, the eaſt winds begin at the month of January, and continue till about the commencement of June. In the month of Auguſt, or September, the contrary direction takes place; and the weſt winds prevail for three or four months. The interval between theſe winds, that is to ſay, from the end of June to the beginning of Auguſt, there is no fixed wind; but the ſea is uſually toſſed by violent tempeſts, proceeding from the north. Theſe winds are always ſubject to their greateſt variations, as they approach the land; ſo that on one ſide of the great peninſula of India, the coaſts are, for near half the year, harraſſed by violent hurricanes, and northern tempeſts; while, on the oppoſite ſide, and all along the coaſts of Coromandel, theſe dreadful tempeſts are wholly unknown. At Java, and Ceylon, a weſt wind begins to reign in the month of September; but at fifteen days of ſouth latitude, this wind is found to be loſt, and the great general trade-wind from the eaſt, is perceived to prevail. On the contrary, at Cochin, in China, the weſt wind begins at March; ſo that theſe Monſoons prevail, at different ſeaſons, throughout the Indies. So that the mariner takes one part of the year to go from Java to the Moluccas; another from Cochin to Molucca; another from Molucca to China; and ſtill another to direct him from China to Japan.

There are winds alſo that may be conſidered as peculiar to certain coaſts; for example, the ſouth wind is almoſt conſtant upon the coaſts of Chili and Peru; weſtern winds almoſt conſtantly prevail on the coaſt of Terra Magellanica; and in the environs of the Streights le Maire. On the coaſts of Malabar, north and north-weſt winds prevail continually; along the coaſt of Guinea, the north-weſt wind is alſo very frequent; and, at a diſtance from the coaſts, the north-eaſt is always found prevailing. From the beginning of November to the end of December, a weſt wind prevails on the coaſts of Japan; and, during the whole winter, no ſhips can leave the port of Cochin, on account of the impetuoſity of the winds that ſet upon the coaſt. Theſe blow with ſuch vehemence that the ports are entirely choaked up with ſand, and even boats themſelves are not able to enter. However, the eaſt winds that prevail for the other half of the year, clear the mouths of their harbours from the accumulations of the preceding winter, and ſet the confined ſhips at liberty. At the Streights of Babelmandel there is a ſouth wind that periodically returns, and which is always followed by a north-eaſt.

Beſide winds thus peculiar to certain coaſts, there are others found to prevail on all the coaſts, in warm climates; which, during one part of the day, blow from the ſhore, and, during another part of it, blow from the ſea. The ſea-breeze, in thoſe countries, as Dampier obſerves, commonly riſes in the morning, about nine, proceeding ſlowly, in a fine ſmall black curl, upon the ſurface of the water, and making its way to refreſh the ſhore. It is gentle at firſt, but encreaſes gradually till twelve, then inſenſibly ſinks away, and is totally huſhed at five. Upon its ceaſing, the land-breeze begins to take its turn, which increaſes till twelve at night, and is ſucceeded, in the morning, by the ſea-breeze again. Without all doubt, nothing could have been more fortunate, for the inhabitants of the warm countries, where thoſe breezes blow, than this alternate refreſhment, which they feel at thoſe ſeaſons when it is moſt wanted. The heat, on ſome coaſts, would be inſupportable, were it not for ſuch a ſupply of air, when the ſun has rarefied all that which lay more immediately under the coaſt. The ſea-breeze temperates the heat of the ſun by day; and the land-breeze corrects the malignity of the dews, and vapours, by night. Where theſe breezes, therefore, prevail, and they are very common, the inhabitants enjoy a ſhare of health, and happineſs, unknown to thoſe that live much farther up the country, or ſuch as live in ſimilar latitudes without this advantange. The cauſe of theſe obviouſly ſeems to ariſe from the rarefaction of the air by the ſun, as their duration continues with its appearance, and alters when it goes down. The ſun, it is obſerved, equally diffuſing his beams upon land and ſea, the land, being a more ſolid body than the water, receives a greater quantity of heat, and reflects it more ſtrongly. Being thus, therefore, heated to a greater degree than the waters, it, of conſequence, drives the air from land out to ſea; but, its influence being removed, the air returns to fill up the former vacuity. Such is the uſual method of accounting for this phaenomena; but, unfortunately, theſe ſea and land breezes are viſitants that come at all hours. On the coaſts of Malabar Buffon, vol. ii. p. 252. , the land-breezes begin at midnight, and continue till noon; then the ſea-breezes take their turn, and continue till midnight again. While, again, at Congo, the land-breezes begin at five, and continue till nine the next day.

But, if the cauſe of theſe be ſo inſcrutable, that are, as we ſee, tolerably regular in their viſitations, what ſhall we ſay to the winds of our own climate, that are continually ſhifting, and incapable of reſt? Some general cauſes may be aſſigned, which nothing but particular experience can apply. And, in the firſt place, it may be obſerved, that clouds, and heat, and, in ſhort, whatever either encreaſes the denſity or the elaſticity of the air, in any one place, will produce a wind there: for the encreaſed activity of the air thus preſſing more powerfully on the parts of it that are adjacent, will drive them forward, and thus go on, in a current, till the whole comes to an equality.

In this manner, as a denſer air produces a wind, on the one hand; ſo will any accident, that contributes to lighten the air, produce it on the other: for, a lighter air may be conſidered as a vacuity, into which the neighbouring air will ruſh: and hence it happens, that when the barometer marks a peculiar lightneſs in the air, it is no wonder that it foretells a ſtorm.

The winds upon large waters are generally more regular than thoſe upon land. The wind at ſea generally blows with an even ſteady gale; the wind at land puffs by intervals, encreaſing its ſtrength, and remitting it, without any apparent cauſe. This, in a great meaſure, may be owing to the many mountains, towers, or trees, that it meets in its way, all contributing either to turn it from its courſe, or interrupt its paſſage.

The eaſt wind blows more conſtantly than any other, and for an obvious reaſon: all other winds are, in ſome meaſure, deviations from it, and partly may owe their origin thereto. It is generally, likewiſe, the moſt powerful, and for the ſame reaſon.

There are often double currents of the air. While the wind blows one way, we frequently ſee the clouds move another. This is almoſt ever the caſe before thunder; for it is well known that the thunder cloud always moves againſt the wind: the cauſe of this ſurprizing appearance has hitherto remained a ſecret. From hence we may conclude, that weathercocks only inform us of that current of the air, which is near the ſurface of the earth; but are often erroneous with regard to the upper regions; and, in fact, Derham has often found them erroneous.

Winds are generally more powerful on elevated ſituations than on the plain, becauſe their progreſs is interrupted by fewer obſtacles. In proportion as we aſcend the heights of a mountain, the violence of the weather ſeems to encreaſe, until we have got above the region of ſtorms, where all is uſually calm and ſerene. Sometimes, however, the ſtorms riſe even to the tops of the higheſt mountains; as we learn from thoſe who have been on the Andes, and as we are convinced by the deep ſnows that crown even the higheſt.

Winds blowing from the ſea are generally moiſter, and more attended with rains, than thoſe which blow over extenſive tracts of land: for the ſea gives off more vapours to the air, and theſe are rolled forward upon land, by the winds blowing from thence Derham's Phiſico Theol. . For this reaſon our eaſterly winds, that blow from the continent, are dry, in compariſon of thoſe that blow from the ſurface of the ocean, with which we are ſurrounded on every other quarter.

In general the winds are more boiſterous in ſpring and autumn, than at other ſeaſons: for, that being the time of high tides, the ſea may communicate a part of its motions to the winds. The ſun, and moon, alſo, which then have a greater effect upon the waters, may alſo have ſome influence upon the winds; for, there being a great body of air ſurrounding the globe, which, if condenſed into water, would cover it to the depth of thirty-two feet, it is evident that the ſun and moon will, to a proportionable degree, affect the atmoſphere, and make a tide of air. This tide will be ſcarce perceivable, indeed; but, without doubt, it actually exiſts; and may contribute to encreaſe the vernal and autumnal ſtorms, which are then known to prevail.

Upon narrowing the paſſage through which the air is driven, both the denſity and the ſwiftneſs of the wind is encreaſed. For as currents of water flow with greater force and rapidity by narrowing their channels, ſo alſo will a current of air, driven through a contracted ſpace, grow more violent and irreſiſtible. Hence we find thoſe dreadful ſtorms that prevail in the defiles of mountains, where the wind, puſhing from behind through a narrow channel, at once encreaſes in ſpeed and denſity, levelling, or tearing up, every obſtacle that riſes to obſtruct its paſſage.

Winds reflected from the ſides of mountains and towers, are often found to be more forceful than thoſe in direct progreſſion. This we frequently perceive near lofty buildings, ſuch as churches or ſteeples, where winds are generally known to prevail, and that much more powerful than at ſome diſtance. The air, in this caſe, by ſtriking againſt the ſide of the building, acquires additional denſity and, therefore, blows with more force.

Theſe differing degrees of denſity, which the air is found to poſſeſs, ſufficiently ſhew that the force of the winds do not depend upon their velocity alone; ſo that thoſe inſtruments called anemometers, which are made to meaſure the velocity of the wind, will by no means give us certain information of the force of the ſtorm. In order to eſtimate this with exactneſs we ought to know its denſity; which alſo theſe are not calculated to diſcover. For this reaſon we often ſee ſtorms, with very powerful effects, that do not ſeem to ſhew any great ſpeed; and, on the contrary, we ſee theſe wind meaſurers go round, with great ſwiftneſs, when ſcarce any damage has followed from the ſtorm.

Such is the nature, and the inconſtancy, of the irregular winds with which we are beſt acquainted. But their effects are much more formidable in thoſe climates, near the tropics, where they are often found to break in upon the ſteady courſe of the trade-winds, and to mark their paſſage with deſtruction. With us the tempeſt is but rarely known, and its ravages are regiſtered as an uncommon calamity; but, in the countries that lie between the tropics, and for a good ſpace beyond them, its viſits are frequent, and its effects anticipated. In theſe regions the winds vary their terrors; ſometimes involving all things in a ſuffocating heat; ſometimes mixing all the elements of fire, air, earth, and water together; ſometimes, with a momentary ſwiftneſs, paſſing over the face of the country, and deſtroying all things in their paſſage; and ſometimes raiſing whole ſandy deſerts in one country, to depoſit them upon ſome other. We have little reaſon, therefore, to envy theſe climates, the luxuriance of their ſoil, or the brightneſs of their ſkies. Our own muddy atmoſphere, that wraps us round in obſcurity, though it fails to gild our proſpects with ſun-ſhine, or our groves with fruitage, nevertheleſs anſwers the calls of induſtry. They may boaſt of a plentiful, but precarious harveſt; while, with us, the labourer toils in a certain expectation of a moderate, but an happy return.

In Egypt Buffon, vol. ii. p. 258 , a kingdom ſo noted for its fertility, and the brightneſs of its atmoſphere, during ſummer, the ſouth winds are ſo hot, that they almoſt ſtop reſpiration; beſides which, they are charged with ſuch quantities of ſand, that they ſometimes darken the air, as with a thick cloud. Theſe ſands are ſo fine, and driven with ſuch violence, that they penetrate every where; even into cheſts, be they ſhut never ſo cloſely. If theſe winds happen to continue for any length of time, they produce epidemic diſeaſes; and are often followed by a great mortality. It is alſo found to rain but very ſeldom in that country; however, the want of ſhowers is richly compenſated by the copiouſneſs of their dews, which greatly tend to promote vegetation.

In Perſia, the winter begins in November, and continues till March. The cold at that time is intenſe enough to congeal the water; and ſnow falls, in abundance, upon their mountains. During the months of March and April, winds ariſe, that blow with great force, and ſeem to uſher in the heats of ſummer. Theſe return again, in autumn, with ſome violence; without, however, producing any dreadful effects. But, during their ſummer, all along the coaſts of the Perſian Gulph, a very dangerous wind prevails, which the natives call the Sameyel, ſtill more dreadful and burning than that of Egypt, and attended with inſtant and fatal effects. This terrible blaſt, which was, perhaps, the peſtilence of the ancients, inſtantly kills all thoſe that it involves in its paſſage. What its malignity conſiſts in, none can tell, as none have ever ſurvived its effects, to give information. It frequently, as I am told, aſſumes a viſible form; and darts, in a kind of bluiſh vapour, along the ſurface of the country. The natives, not only of Perſia, but Arabia, talk of its effects with terror; and their poets have not failed to heighten them, with the aſſiſtance of imagination. They have deſcribed it as under the conduct of a miniſter of vengeance, who governs its terrors, and raiſes, or depreſſes it, as he thinks proper Herbelot. Bibliotheque Oriental. . Theſe deadly winds are alſo known along the coaſts of India, at Necapatan, Maſulipatan, and Petapoli. But, luckily for mankind, the ſhortneſs of their duration diminiſhes the injuries that might enſue from their malignity.

The Cape of Good Hope, as well as many iſlands in the Weſt-Indies, are famous for their hurricanes, and that extraordinary kind of cloud which is ſaid to produce them. This cloud, which is the fore-runner of an approaching hurricane, appears, when firſt ſeen, like a ſmall black ſpot, on the verge of the horizon; and is called, by ſailors, the bull's eye, from being ſeen ſo minute at a vaſt diſtance. All this time, a perfect calm reigns over the ſea and land, while the cloud grows gradually broader as it approaches. At length, coming to the place where its fury is to fall, it inveſts the whole horizon with darkneſs. During all the time of its approach, an hollow murmur is heard in the cavities of the mountains; and beaſts and animals, ſenſible of its approach, are ſeen running over the fields, to ſeek for ſhelter. Nothing can be more terrible than its violence when it begins. The houſes in thoſe countries, which are made of timber, the better to reſiſt its fury, bend to the blaſt like oſiers, and again recover their rectitude. The ſun, which, but a moment before, blazed with meridian ſplendor, is totally ſhut out; and a midnight darkneſs prevails, except that the air is inceſſantly illuminated with gleams of lightening, by which one can eaſily ſee to read. The rain falls, at the ſame time, in torrents; and its deſcent has been reſembled to what pours from the ſpouts of our houſes after a violent ſhower. Theſe hurricanes are not leſs offenſive to the ſenſe of ſmelling alſo; and never come without leaving the moſt noiſome ſtench behind them. If the ſeamen alſo lay by their wet cloaths, for twenty-four hours, they are all found ſwarming with little white maggots, that were brought with the hurricane. Our firſt mariners, when they viſited theſe regions, were ignorant of its effects, and the ſigns of its approach; their ſhips, therefore, were daſhed to the bottom at the firſt onſet; and numberleſs were the wrecks which the hurricane occaſioned. But, at preſent, being forewarned of its approach, they ſtrip their maſts of all their ſails, and thus patiently abide its fury. Theſe hurricanes are common in all the tropical climates. On the coaſts of Guinea they have frequently three, or four, in a day, that thus ſhut out the heavens, for a little ſpace; and when paſt leave all again in former ſplendor. • hey chiefly prevail, on that coaſt, in the intervals of the trade winds; the approach of which clears the air of its meteors, and gives theſe mortal ſhowers that little degree of wholeſomeneſs which they poſſeſs. They chiefly obtain there during the months of April and May; they are known, at Loango, from January to April; on the oppoſite coaſt of Africa, the hurricane ſeaſon begins at May; and, in general, whenever a trade wind begins to ceaſe, theſe irregular tempeſts are found to exert their fury.

All this is terrible; but there is a tempeſt, known in thoſe climates, more formidable than any we have hitherto been deſcribing, which is called, by the Spaniards, a Tornado. As the former was ſeen arriving from one part of the heavens, and making a line of deſtruction; ſo the winds in this ſeem to blow from every quarter, and ſettle upon one deſtined place, with ſuch fury, that nothing can reſiſt their vehemence. When they have all met, in their central ſpot, then the whirlwind begins with circular rapidity. The ſphere, every moment widens, as it continues to turn, and catches every object that lies within its attraction. This, alſo, like the former, is preceded by a flattering calm; the air is every where huſhed; and the ſea is as ſmooth as poliſhed glaſs: however, as its effects are more dreadful than thoſe of the ordinary hurricane, the mariner tries all the power of his ſkill to avoid it; which, if he fails of doing, there is the greateſt danger of his going to the bottom. All along the coaſts of Guinea, beginning about two degrees north of the line, and ſo downward, lengthwiſe, for about a thouſand miles, and as many broad, the ocean is unnavigable, upon account of theſe tornados. In this torpid region there reigns unceaſing tornados, or continual calms; among which, whatever ſhip is ſo unhappy as to fall, is totally deprived of all power of eſcaping. In this dreadful repoſe of all the elements, the ſolitary veſſel is obliged to continue, without a ſingle breeze to aſſiſt the mariner's wiſhes, except thoſe whirlwinds, which only ſerve to encreaſe his calamity. At preſent, therefore, this part of the ocean is totally avoided; and, although there may be much gold along the coaſts of that part of Africa, to tempt avarice, yet there is ſomething, much more dreadful than the fabled dragon of antiquity, to guard the treaſure. As the internal parts of that country are totally unknown to travellers, from their burning ſands and extenſive deſarts, ſo here we find a vaſt tract of ocean, lying off its ſhores, equally unviſited by the mariner.

But of all thoſe terrible tempeſts that deform the face of Nature, and repreſs human preſumption, the ſandy tempeſts of Arabia and Africa, are the moſt terrible, and ſtrike the imagination moſt ſtrongly. To conceive a proper idea of theſe, we are by no means to ſuppoſe them reſembling thoſe whirlwinds of duſt that we ſometimes ſee ſcattering in our air, and ſprinkling their contents upon our roads, or meadows. The ſand-ſtorm of Africa, exhibits a very different appearance. As the ſand of which the whirlwind is compoſed, is exceſſively fine, and almoſt reſembles the parts of water, its motion entirely reſembles that of a fluid; and the whole plain ſeems to float onward, like a ſlow inundation. The body of ſand thus rolling, is deep enough to bury houſes and palaces in its boſom: travellers who are croſſing thoſe extenſive deſerts, perceive its approach at a diſtance; and, in general, have time to avoid it, or turn out of its way, as it generally extends but to a moderate breadth. However, when it is extremely rapid, or very extenſive, as ſometimes is the caſe, no ſwiftneſs, no art, can avail; nothing then remains, but to meet death with fortitude, and ſubmit to be buried alive with reſignation.

It is happy for us of Britain, that we have no ſuch calamity to fear; for, from this, even ſome parts of Europe are not entirely free. We have an account given us, in the Hiſtory of the French Academy, of a miſerable town in France, that is conſtantly in danger of being buried under a ſimilar inundation; with which I will take leave to cloſe this chapter. "In the neighbourhood of St. Paul de Leon, in Lower Brittany Hiſtoire de l'Accademic des Sciences, an. 1722. , there lies a tract of country along the ſea-ſide, which before the year 1666 was inhabited, but now lies deſerted, by reaſon of the ſands which cover it, to the height of twenty feet; and which every year advance more and more in land, and gain ground continually. From the time mentioned above, the ſand has buried more than ſix leagues of the country inward; and it is now but half a league from the town of St. Paul; ſo that, in all appearance, the inhabitants muſt be obliged to abandon it entirely. In the country that has been overwhelmed, there are ſtill to be ſeen the tops of ſome ſteeples peeping through the ſand, and many chimnies that ſtill remain above this ſandy ocean. The inhabitants, however, had ſufficient time to eſcape; but being deprived of their little all, they had no other reſource but begging for their ſubſiſtence. This calamity chiefly owes its advancement to a north, or an eaſt-wind, raiſing the ſand, which is extremely fine, in ſuch great quantities, and with ſuch velocity, that M. Deſlands, who gave the account, ſays, that while he was walking near the place, during a moderate breeze of wind, he was obliged, from time to time, to ſhake the ſand from his cloaths and his hat, on which it was lodged in great quantities, and made them too heavy to be eaſily borne. Still further, when the wind was violent, it drove the ſand acroſs a little arm of the ſea, into the town of Roſcoff, and covered the ſtreets of that place two feet deep; ſo that they have been obliged to carry it off in carts. It may alſo be obſerved, that there are ſeveral particles of iron mixed with the ſand, which are readily affected by the loadſtone. The part of the coaſt that furniſhes theſe ſands, is a tract of about four leagues in length; and is upon a level with the ſea at high-water. The ſhore lies in ſuch a manner as to leave its ſands ſubject only to the north and eaſt winds, that bear them farther up the ſhore. It is eaſy to conceive how the ſame ſand that has at one time been borne a ſhort way in land, may, by ſome ſucceeding and ſtronger blaſt, be carried up much higher; and thus the whole may continue advancing forward, deluging the plain, and totally deſtroying its fertility. At the ſame time, the ſea, from whence this deluge of ſand proceeds, may furniſh it in inexhauſtible quantities. This unhappy country, thus overwhelmed in ſo ſingular a manner, may well juſtify what the ancients and the moderns have reported concerning thoſe tempeſts of ſand in Africa, that are ſaid to deſtroy villages, and even armies, in their boſom."

IN proportion as the ſubſtances of nature are more compounded and combined, their appearances become more inexplicable and amazing. The properties of water have been very nearly aſcertained. Many of the qualities of air, earth, and fire, have been diſcovered, and eſtimated; but when theſe come to be united by Nature, they often produce a reſult which no artificial combinations can imitate; and we ſtand ſurprized, that although we are poſſeſſed of all thoſe ſubſtances which Nature makes uſe of, ſhe ſhews herſelf a much more various operator than the moſt ſkilful chymiſt ever appeared to be. Every cloud that moves, and every ſhower that falls, ſerves to mortify the philoſopher's pride, and to ſhew him hidden qualities in air and water, that he finds it difficult to explain. Dews, hail, ſnow, and thunder, are not leſs difficult for being more common. Indeed, when we reflect on the manner in which Nature performs any one of theſe operations, our wonder encreaſes. To ſee water, which is heavier than air, riſing in air, and then falling in a form ſo very different from that in which i • roſe; to ſee the ſame fluid at one time deſcending in the form of hail, at another in that of ſnow; to ſee two clouds, by daſhing againſt each other, producing an electrical fire, which no watery compoſition that we know of can effect; theſe, I ſay, ſerve ſufficiently to excite our wonder; and ſtill the more, in proportion as the objects are ever preſſing on our curioſity. Much, however, has been written concerning the manner in which Nature operates in theſe productions; as nothing is ſo ungrateful to mankind as hopeleſs ignorance.

And firſt, with regard to the manner in which water evaporates, and riſes to form clouds, much has been advanced, and many theories deviſed. All water Spectacle de la Nature, vol. iii. , ſay ſome, has a quantity of air mixed with it; and the heat of the ſun darting down, diſengages the particles of this air from the groſſer fluid: the ſun's rays being reflected back from the water, carry back with them thoſe bubbles of air and water which, being lighter than the condenſed air, will aſcend till they meet with a more rarefied air; and they will then ſtand ſuſpended. Experience, however, proves nothing of all this. Particles of air or fire, are not thus known to aſcend with a thin coat of water; and, in fact, we know that the little particles of ſteam are ſolid drops of water. But beſides this, water is known to evaporate more powerfully in the ſevereſt froſt, than when the air is moderately warm Memoires de l'Accademie des Sciences, an. 1705. . Doctor Hamilton, therefore, of the univerſity of Dublin, rejecting this theory, has endeavoured to eſtabliſh another. According to him, as aqua fortis is a menſtruum that diſſolves iron, and keeps it mixed in the fluid; as aqua regia is a menſtruum that diſſolves gold; or as water diſſolves ſalts to a certain quantity; ſo air is a menſtruum that corrodes and diſſolves a certain quantity of water, and keeps it ſuſpended above. But however ingenious this may be, it can hardly be admitted; as we know, by Marriotte's experiment Mariotte, de la Nature de l'Air, p. 97, 106. , that if water and air be encloſed together, inſtead of the air's acting as a menſtruum upon the water, the water will act as a menſtruum upon the air, and take it all up. We know alſo, that of two bodies, that which is moſt fluid and penetrating, is moſt likely to be the menſtruum of the other; but water is more fluid and penetrating than air, and, therefore, the moſt likely of the two to be the menſtruum. We know that all bodies are more ſpeedily acted upon, the more their parts are brought into contact with the menſtruum that diſſolves them: but water, incloſed with compreſt air, is not the more diminiſhed thereby See Boyle's Works, vol. ii. p. 619. . In ſhort, we know, that cold, which diminiſhes the force of other menſtruums, is often found to promote evaporation. In this variety of opinion, and uncertainty of conjecture, I cannot avoid thinking that a theory of evaporation may be formed upon very ſimple and obvious principles, and embarraſſed, as far as I can conceive, with very few objections.

We know that a repelling power prevails in nature, not leſs than an attractive one. This repulſion prevails ſtrongly between the body of fire and that of water. If I plunge the end of a red hot bar of iron into a veſſel of water, the fluid riſes, and large drops of it fly up in all manner of directions, every part bubbling and ſteaming until the iron be cold. Why may we not, for a moment, compare the rays of the ſun, darted directly upon the ſurface of the water, to ſo many bars of red hot iron; each bar, indeed, infinitely ſmall, but not the leſs powerful? In this caſe, wherever a ray of fire darts, the water, from its repulſive quality, will be driven on all ſides; and, of conſequence, as in the caſe of the bar of iron, a part of it will riſe. The parts thus riſing, however, will be extremely ſmall; as the ray that darts is extremely ſo. The aſſemblage of the rays darting upon the water in this manner, will cauſe it to riſe in a light thin ſteam above the ſurface; and as the parts of this ſteam are extremely minute, they will be lighter than air, and, conſequently, float upon it. There is no need for ſuppoſing them bubbles of water, filled with fire; for any ſubſtance, even gold itſelf, will float on air, if its parts be made ſmall enough; or, in other words, if its ſurface be ſufficiently encreaſed. This water, thus diſengaged from the general maſs, will be ſtill farther attenuated and broken by the reflected rays, and, conſequently, more adapted for aſcending.

From this plain account, every appearance in evaporation may be eaſily deduced. The quantity of heat encreaſes evaporation, becauſe it raiſes a greater quantity of ſteam. The quantity of wind encreaſes evaporation; for, by waving the ſurface of the water, it thus expoſes a greater ſurface to the evaporating rays. A dry froſt, in ſome meaſure, aſſiſts the quantity of evaporation; as the quantity of rays are found to be no way diminiſhed thereby. Moiſt weather alone prevents evaporation; for the rays being abſorbed, refracted, and broken, by the intervening moiſture, before they arrive at the ſurface, cannot produce the effect; and the vapour will riſe in a ſmall proportion.

Thus far we have accounted for the aſcent of vapours; but to account for their falling again, is attended with rather more difficulty. We have already obſerved, that the particles of vapour, diſengaged from the ſurface of the water, will be broken and attenuated in their aſcent, by the reflected, and even the direct rays, that happen to ſtrike upon their minute ſurfaces. They will, therefore, continue to aſcend, till they riſe above the operation of the reflected rays, which reaches but to a certain height above the ſurface of the earth. Being arrived at this region, which is cold for want of reflected heat, they will be condenſed, and ſuſpended in the form of clouds. Some vapours that aſcend to great heights, will be frozen into ſnow; others, that are condenſed lower down, will put on the appearance of a miſt, which we find the clouds to be, when we aſcend among them, as they hang along the ſides of a mountain. Theſe clouds of ſnow and rain, being blown about by winds, are either entirely ſcattered and diſperſed above, or they are ſtill more condenſed by motion, like a ſnow-ball, that grows more large and ſolid as it continues to roll. At laſt, therefore, they will become too weighty for the air which firſt raiſed them, to ſuſtain; and they will deſcend, with their exceſs of weight, either in ſnow or rain. But as they will fall precipitately, when they begin to deſcend, the air, in ſome meaſure, will reſiſt the falling; for, as the deſcending fluid gathers velocity in its precipitation, the air will encreaſe its reſiſtance to it, and the water will, therefore, be thus broken into rain; as we ſee, that water which falls from the tops of houſes, though it begins in a ſpout, ſeparates into drops before it has got to the bottom. Were it not for this happy interpoſition of the air, between us and the water falling from a conſiderable height above us, a drop of rain might fall with dangerous force, and an hail-ſtone might ſtrike us with fatal rapidity.

In this manner, evaporation is produced by day; but when the ſun goes down, a part of that vapour which his rays had excited, being no longer broken, and attenuated by the reflecting rays, it will become heavier than the air, even before it has reached the clouds; and it will, therefore, fall back in dews, which differ only from rain in deſcending before they have had time to condenſe into a viſible form.

Hail, the Carteſians ſay, is a frozen cloud, half melted, and frozen again in its deſcent. An hoar-froſt is but a frozen dew. Lightening we know to be an electrical flaſh, produced by the oppoſition of two clouds: and thunder to be the ſound proceeding from the ſame, continued by an echo reverberated among them. It would be to very little purpoſe, to attempt explaining exactly how theſe wonders are effected: we have as yet but little inſight into the manner in which theſe meteors are found to operate upon each other; and, therefore, we muſt be contented with a detail rather of their effects than their cauſes.

In our own gentle climate, where Nature wears the mildeſt and kindeſt aſpect, every meteor ſeems to befriend us. With us, rains fall in refreſhing ſhowers, to enliven our fields, and to paint the landſcape with a more vivid beauty. Snows cover the earth, to preſerve its tender vegetables from the inclemency of the departing winter. The dews deſcend with ſuch an imperceptible fall as no way injures the conſtitution. Thunder itſelf is ſeldom injurious; and it is often wiſhed by the huſbandman, to clear the air, and to kill numberleſs inſects that are noxious to vegetation. Hail is the moſt injurious meteor that is known in our climate; but it ſeldom viſits us with violence, and then its fury is but tranſient.

One of the moſt dreadful ſtorms we hear of Phil. Tranſ. vol. ii. p. 147. , was that at Hertfordſhire, in the year 1697. It began by thunder and lightening, which continued for ſome hours, when ſuddenly a black cloud came forward, againſt the wind, and marked its paſſage with devaſtation. The hail-ſtones which it poured down, being meaſured, were found to be many of them fourteen inches round, and, conſequently, as large as a bowling-green ball. Wherever it came, every plantation fell before it; it tore up the ground, ſplit great oaks, and other trees, without number; the fields of rye were cut down, as if levelled with a ſcythe; wheat, oats, and barley, ſuffered the ſame damage. The inhabitants found but a precarious ſhelter, even in their houſes, their tiles and windows being broke by the violence of the hail-ſtones, which, by the force with which they came, ſeemed to have deſcended from a great height. The birds, in this univerſal wreck, vainly tried to eſcape by flight; pidgeons, crows, rooks, and much more of the ſmaller and feebler kinds, were brought down. An unhappy young man, who had not time to take ſhelter, was killed; one of his eyes was ſtruck out of his head, and his body was all over black with the bruiſes: another had juſt time to eſcape, but not without the moſt imminent danger, his body being bruiſed all over. But what is moſt extraordinary, all this fell within the compaſs of a mile.

Mezeray, in his Hiſtory of France, tells us of a ſhower of hail much more terrible, which happened in the year 1510, when the French monarch invaded Italy. There was, for a time, an horrid darkneſs, thicker than that of midnight, which continued till the terrors of mankind were changed to ſtill more terrible objects, by thunder and lightening breaking the gloom, and bringing on ſuch a ſhower of hail, as no hiſtory of human calamities could equal. Theſe hail-ſtones were of a bluiſh colour; and ſome of them weighed not leſs than an hundred pounds. A noiſome vapour of ſulphur attended the ſtorm. All the birds and beaſts of the country were entirely deſtroyed. Numbers of the human race ſuffered the ſame fate. But what is ſtill more extraordinary, the fiſhes themſelves found no protection from their native element; but were equal ſufferers in the general calamity.

Theſe, however, are terrors that are ſeldom exerted in our mild climates. They only ſerve to mark the page of hiſtory with wonder; and ſtand as admonitions to mankind, of the various ſtores of puniſhment in the hands of the Deity, which his power can treaſure up, and his mercy can ſuſpend.

In the temperate zones, therefore, meteors are rarely found thus terrible; but between the tropics, and near the poles, they aſſume very dreadful and various appearances. In thoſe inclement regions, where cold and heat exert their chief power, meteors ſeem peculiarly to have fixed their reſidence. They are ſeen there in a thouſand terrifying forms, aſtoniſhing to Europeans, yet diſregarded by the natives, from their frequency. The wonders of air, fire, and water, are there combined, to produce the moſt tremendous effects; and to ſport with the labours and apprehenſions of mankind. Lightenings, that flaſh without noiſe; hurricanes, that tear up the earth; clouds, that all at once pour down their contents, and produce an inſtant deluge; mock ſuns; northern lights, that illuminate half the hemiſphere; circular rainbows; halo's; fleeting balls of fire; clouds, reflecting back the images of things on earth, like mirrors; and water-ſpouts, that burſt from the ſea, to join with the miſts that hang immediately above them. Theſe are but a part of the phaenomena that are common in thoſe countries; and from many of which, our own climate is, in a great meaſure, exempted.

The meteors of the torrid zone, however, are different from thoſe that are found near the polar circles: and it may readily be ſuppoſed, that in thoſe countries where the ſun exerts the greateſt force in raiſing vapours of all kinds, there ſhould be the greateſt quantity of meteors. Upon the approach of the winter months, as they are called, under the line, which uſually begin about May, the ſky, from a fiery brightneſs, begins to be overcaſt, and the whole horizon ſeems wrapt in a muddy cloud. Miſts and vapours ſtill continue to riſe; and the air, which ſo lately before was clear and elaſtic, now becomes humid, obſcure, and ſtifling: the fogs become ſo thick, that the light of the ſun ſeems in a manner excluded; nor would its preſence be known, but for the intenſe and ſuffocating heat of its beams, which dart through the gloom, and, inſtead of diſſipating, only ſerve to encreaſe the miſt. After this preparation, there follows an almoſt continual ſucceſſion of thunder, rain, and tempeſts. During this dreadful ſeaſon, the ſtreets of cities flow like rivers; and the whole country wears the appearance of an ocean. The inhabitants often make uſe of this opportunity to lay in a ſtock of freſh water, for the reſt of the year; as the ſame cauſe which pours down the deluge at one ſeaſon, denies the kindly ſhower at another. The thunder which attends the fall of theſe rains, is much more terrible than that we are generally acquainted with. With us, the flaſh is ſeen at ſome diſtance, and the noiſe ſhortly after enſues; our thunder genenerally rolls on one quarter of the ſky, and one ſtroke purſues another. But here it is otherwiſe; the whole ſky, all around, ſeems illuminated with unremitted flaſhes of lightening; every part of the air ſeems productive of its own thunders; and every cloud produces its own ſhock. The ſtrokes come ſo thick, that the inhabitants can ſcarce mark the intervals; but all is one unremitted roar of elementary confuſion. It ſhould ſeem, however, that the lightening of thoſe countries is not ſo fatal, or ſo dangerous, as with us; ſince, in this caſe, the torrid zone would be uninhabitable.

When theſe terrors have ceaſed, with which, however, the natives are familiar, meteors of another kind begin to make their appearance. The intenſe beams of the ſun, darting upon ſtagnant waters, that generally cover the ſurface of the country, raiſe vapours of various kinds. Floating bodies of fire, which aſſume different names, rather from their accidental forms, than from any real difference between them, are ſeen without ſurprize. The draco volans, or flying dragon, as it is called; the ignis fatuus, or wandering fire; the fires of St. Helmo, or the mariner's light, are every where frequent; and of theſe we have numberleſs deſcriptions. "As I was riding in Jamaica," ſays, Mr. Barbham, "one morning from my habitation, ſituated about three miles northweſt from Jago de la Bega, I ſaw a ball of fire, appearing to me of the bigneſs of a bomb, ſwiftly falling down with a great blaze. At firſt I thought it fell into the town; but when I came nearer, I ſaw many people gathered together, a little to the ſouthward, in the Savannah, to whom I rode up, to enquire the cauſe of their meeting: they were admiring, as I found, the ground's being ſtrangely broke up and ploughed by a ball of fire; which, as they ſaid, fell down there. I obſerved there were many holes in the ground; one in the middle of the bigneſs of a man's head, and five or ſix ſmaller round about it, of the bigneſs of one's fiſt, and ſo deep as not to be fathomed by ſuch implements as were at hand. It was obſerved, alſo, that all the green herbage was burnt up, near the holes; and there continued a ſtrong ſmell of ſulphur near the place, for ſome time after."

Ulloa gives an account of one of a ſimilar kind, at Quito Ulloa, vol. i. p. 41. . "About nine at night," ſays he, "a globe of fire appeared to riſe from the ſide of the mountain Pichinca, and ſo large, that it ſpread a light over all the part of the city facing that mountain. The houſe where I lodged, looking that way, I was ſurprized with an extraordinary light, darting through the crevices of the window-ſhutters. On this appearance, and the buſtle of the people, in the ſtreet, I haſtened to the window, and came time enough to ſee it, in the middle of its career; which continued from weſt to ſouth, till I loſt ſight of it, being intercepted by a mountain, that lay between me and it. It was round; and its apparent diameter about a foot. I obſerved it to riſe from the ſides of Pichinca; although, to judge from its courſe, it was behind that mountain where this congeries of inflammable matter was kindled. In the firſt half of its viſible courſe it emitted a prodigious effulgence, then it began gradually to grow dim; ſo that, upon its diſappearing behind the intervening mountain, its light was very faint."

Meteors, of this kind, are very frequently ſeen between the tropics; but they ſometimes, alſo, viſit the more temperate regions of Europe. We have the deſcription of a very extraordinary one, given us by Montanari, that ſerves to ſhew to what great heights, in our atmoſphere, theſe vapours are found to aſcend. In the year 1676, a great globe of fire was ſeen at Bononia, in Italy, about three quarters of an hour after ſun-ſet. It paſt weſtward, with a moſt rapid courſe, and at the rate of not leſs than a hundred and ſixty miles in a minute, which is much ſwifter than the force of a cannon-ball, and, at laſt, ſtood over the Adriatic ſea. In its courſe it croſſed over all Italy; and, by computation, it could not have been leſs than thirty-eight miles above the ſurface of the earth. In the whole line of its courſe, wherever it approached, the inhabitants below could diſtinctly hear it, with a hiſſing noiſe, reſembling that of a fire-work. Having paſt away to ſea, towards Corſica, it was heard, at laſt, to go off with a moſt violent exploſion, much louder than that of a cannon; and, immediately after, another noiſe was heard, like the rattling of a great cart, upon a ſtony pavement; which was, probably, nothing more than the echo of the former ſound. Its magnitude, when at Bononia, appeared twice as long as the moon, one way; and as broad the other; ſo that, conſidering its height, it could not have been leſs than a mile long, and half a mile broad. From the height at which this was ſeen, and there being no volcano, on that quarter of the world, from whence it came, it is more than probable that this terrible globe was kindled on ſome part of the contrary ſide of the globe, in thoſe regions of vapours, which we have been juſt deſcribing; and thus, riſing above the air, and paſſing, in a courſe oppoſite to that of the earth's motion, in this manner it acquired its amazing rapidity.

To theſe meteors, common enough ſouthward, we will add one more of a very uncommon kind, which was ſeen, by Ulloa, at Quito, in Peru; the beauty of which will, in ſome meaſure, ſerve to relieve us, after the deſcription of thoſe hideous ones preceding. "At day-break," ſays he, "the whole mountain of Pambamarca, where we then reſided, was encompaſſed with very thick clouds; which the riſing of the ſun diſperſed ſo far, as to leave only ſome vapours, too fine to be ſeen. On the ſide oppoſite to the riſing ſun, and about ten fathoms diſtant from the place where we were ſtanding, we ſaw, as in a looking-glaſs, each his own image; the head being, as it were, the center of three circular rainbows, one without the other, and juſt near enough to each other as that the colours of the internal verged upon thoſe more external; while round all was a circle of white, but with a greater ſpace between. In this manner theſe circles were erected, like a mirror, before us; and as we moved, they moved, in diſpoſition and order. But, what is moſt remarkable, though we were ſix in number, every one ſaw the phenomenon, with regard to himſelf, and not that relating to others. The diameter of the arches gradually altered, as the ſun roſe above the horizon; and the whole, after continuing a long time, inſenſibly faded away. In the beginning, the diameter of the inward iris, taken from its laſt colour, was about five degrees and a half; and that of the white arch, which ſurrounded the reſt, was not leſs than ſixty-ſeven degrees. At the beginning of the phenomenon, the arches ſeemed of an oval or eliptical figure, like the diſk of the ſun; and afterwards became perfectly circular. Each of theſe was of a red colour, bordered with an orange; and the laſt bordered by a bright yellow, which altered into a ſtraw colour, and this turned to a green; but, in all, the external colour remained red." Such is the deſcription of one of the moſt beautiful illuſions that has been ever ſeen in nature. This alone ſeems to have combined all the ſplendours of optics in one view. To underſtand the manner, therefore, how this phaenomena was produced, would require a perfect knowledge of optics; which it is not our preſent province to enter upon. It will be ſufficient here, therefore, only to obſerve, that all theſe appearances ariſe from the denſity of the cloud, together with its uncommon and peculiar ſituation, with reſpect to the ſpectator and the ſun. It may be obſerved, that but one of theſe three rainbows was real, the reſt being only reflections thereof. It may alſo be obſerved, that whenever the ſpectator ſtands between the ſun and a cloud of falling rain, a rainbow is ſeen, which is nothing more than the reflection of the different coloured rays of light from the boſom of the cloud. If, for inſtance, we take a glaſs globe, filled with water, and hang it up before us, oppoſite the ſun, in many ſituations, it will appear tranſparent; but if it is raiſed higher, or ſideways, to an angle of forty-five degrees, it will at firſt appear red; altered a very little higher, yellow; then green, then blue, then violet colour; in ſhort, it will aſſume ſucceſſively all the colours of the rainbow; but, if raiſed higher, ſtill it will become tranſparent again. A falling ſhower may be conſidered as an infinite number of theſe little tranſparent globes, aſſuming different colours, by being placed at the proper heights. The reſt of the ſhower will appear tranſparent, and no part of it will ſeem coloured; but ſuch as are at angles of forty-five degrees from the eye, forty-five degrees upward, forty-five degrees on each ſide, and forty-five degrees downward, did not the plain of the earth prevent us. We, therefore, ſee only an arch of the rainbow, the lower part being cut off from our ſight by the earth's interpoſition. However, upon the tops of very high mountains, circular rainbows are ſeen, becauſe we can ſee to an angle of forty-five degrees downward, as well as upward, or ſideways, and therefore we take in the rainbow's complete circle.

In thoſe forlorn regions, round the poles, the meteors, though of another kind, are not leſs numerous and alarming. When the winter begins, and the cold prepares to ſet in, the ſame miſty appearance which is produced in the ſouthern climates by the heat, is there produced by the contrary extreme Paul Egede's Hiſtory of Greenland. . The ſea ſmokes like an oven, and a fog ariſes, which mariners call the froſt ſmoke. This cutting miſt moſt commonly raiſes bliſters on ſeveral parts of the body; and, as ſoon as it is wafted to ſome colder part of the atmoſphere, it freezes to little icy particles, which are driven by the wind, and create ſuch a cutting cold on land, that the limbs of the inhabitants are ſometimes frozen, and drop off.

There alſo, halos, or luminous circles round the moon, are oftener ſeen than in any other part of the earth, being formed by the froſt ſmoke; although the air otherwiſe ſeems to be clear. A lunar rainbow alſo, is often ſeen there, though ſomewhat different from that which is common with us; as it appears of a pale white, ſtriped with grey. In theſe countries alſo, the aurora borealis ſtreams, with peculiar luſtre, and variety of colours. In Greenland it generally ariſes in the eaſt, and darts its ſportive fires, with variegated beauty, over the whole horizon. Its appearance is almoſt conſtant in winter; and, at thoſe ſeaſons when the ſun departs, to return no more for half a year, this meteor kindly riſes to ſupply its beams, and affords ſufficient light for all the purpoſes of exiſtence. However, in the very midſt of their tedious night, the inhabitants are not entirely forſaken. The tops of the mountains are often ſeen painted with the red rays of the ſun; and the poor Greenlander from thence begins to date his chronology. It would appear whimſical to read a Greenland calendar, in which we might be told, that one of their chiefs, having lived forty days, died, at laſt, of a good old age; and that his widow continued for half a day, to deplore his loſs, with great fidelity, before ſhe admitted a ſecond huſband.

The meteors of the day, in theſe countries, are not leſs extraordinary than thoſe of the night: mock ſuns are often reflected upon an oppoſite cloud; and the ignorant ſpectator fancies that there are often three or four real ſuns in the firmament at the ſame time. In this ſplendid appearance the real ſun is always readily known by its ſuperior brightneſs, every reflexion being ſeen with diminiſhed ſplendour. The ſolar rainbow there is often ſeen different from ours. Inſtead of a pleaſing variety of colours, it appears of a pale white, edged with a ſtripe of duſky yellow; the whole being reflected from the boſom of a frozen cloud.

But, of all the meteors which mock the imagination with an appearance of reality, thoſe ſtrange illuſions that are ſeen there, in fine ſerene weather, are the moſt extraordinary and entertaining. "Nothing," ſays Krantz, "ever ſurprized me more, than, on a fine warm ſummer's day, to perceive the iſlands that lie four leagues weſt of our ſhore, putting on a form quite different from what they are known to have. As I ſtood gazing upon them, they appeared, at firſt, infinitely greater than what they naturally are; and ſeemed as if I viewed them through a large magnifying glaſs. They were not thus only made larger, but brought nearer to me. I plainly deſcried every ſtone upon the land, and all the furrows filled with ice, as if I ſtood cloſe by. When this illuſion had laſted for a while, the proſpect ſeemed to break up, and a new ſcene of wonder to preſent itſelf. The iſlands ſeemed to travel to the ſhore, and repreſented a wood, or a tall cut hedge. The ſcene then ſhifted, and ſhewed the appearance of all ſorts of curious figures; as ſhips with ſails, ſtreamers, and flags; antique elevated caſtles, with decayed turrets; and a thouſand forms, for which fancy found a reſemblance in nature. When the eye had been ſatisfied with gazing, the whole groupe of riches ſeemed to riſe in air, and at length vaniſh into nothing. At ſuch times the weather is quite ſerene and clear; but compreſt with ſuch ſubtle vapours, as it is in very hot weather; and theſe appearing between the eye and the object, give it all that variety of appearances which glaſſes of different refrangibilities would have done." Mr. Krantz obſerves that, commonly a couple of hours afterwards, a gentle weſt wind and a viſible miſt follows, which puts an end to this luſus naturae.

It were eaſy to ſwell this catalogue of meteors with the names of many others, both in our own climate and in other parts of the world. Such as falling ſtars, which are thought to be no more than unctuous vapours, raiſed from the earth to ſmall heights, and continuing to ſhine till that matter which firſt raiſed, and ſupported them, being burnt out, they fall back again to the earth, with extinguiſhed flame. Burning ſpears, which are a peculiar kind of aurora borealis; bloody rains which are ſaid to be the excrements of an inſect, that at that time has been raiſed into the air. Showers of ſtones, fiſhes, and ivy-berries, at firſt, no doubt, raiſed into the air by tempeſts, in one country, and falling at ſome conſiderable diſtance, in the manner of rain, to aſtoniſh another. But omitting theſe, of which we know little more than what is thus briefly mentioned, I will conclude this chapter with the deſcription of a water-ſpout; a moſt ſurprizing phenomenon; not leſs dreadful to mariners than aſtoniſhing to the obſerver of nature.

Theſe ſpouts are ſeen very commonly in the tropical ſeas, and ſometimes in our own. Thoſe ſeen by Tournefort, in the Mediterranean, he has deſcribed as follows. "The firſt of theſe," ſays this great botaniſt, "that we ſaw, was about a muſket-ſhot from our ſhip. There we perceived the water began to boil, and to riſe about a foot above its level. The water was agitated and whitiſh; and above its ſurface there ſeemed to ſtand a ſmoke, ſuch as might be imagined to come from wet ſtraw before it begins to blaze. It made a ſort of a murmuring ſound, like that of a torrent, heard at a diſtance, mixed, at the ſame time, with an hiſſing noiſe, like that of a ſerpent: ſhortly after we perceived a column of this ſmoke riſe up to the clouds, at the ſame time whirling about with great rapidity. It appeared to be as thick as one's finger; and the former ſound ſtill continued. When this diſappeared, after laſting for about eight minutes, upon turning to the oppoſite quarter of the ſky, we perceived another, which began in the manner of the former; preſently after a third appeared in the weſt; and inſtantly beſide it ſtill another aroſe. The moſt diſtant of theſe three could not be above a muſket-ſhot from the ſhip. They all continued like ſo many heaps of wet ſtraw ſet on fire, that continued to ſmoke, and to make the ſame noiſe as before. We ſoon after perceived each, with its reſpective canal, mounting up in the clouds, and ſpreading where it touched; the cloud, like the mouth of a trumpet, making a figure, to expreſs it intelligibly, as if the tail of an animal were pulled at one end by a weight. Theſe canals were of a whitiſh colour, and ſo tinged, as I ſuppoſe, by the water which was contained in them; for, previous to this, they were apparently empty, and of the colour of tranſparent glaſs. Theſe canals were not ſtraight, but bent in ſome parts, and far from being perpendicular, but riſing in their clouds with a very inclined aſcent. But what is very particular, the cloud to which one of them was pointed happening to be driven by the wind, the ſpout ſtill continued to follow its motion, without being broken; and paſſing behind one of the others, the ſpouts croſſed each other, in the form of a St. Andrew's croſs. In the beginning they were all about as thick as one's finger, except at the top, where they were broader, and two of them diſappeared; but ſhortly after, the laſt of the three encreaſed conſiderably; and its canal, which was at firſt ſo ſmall, ſoon became as thick as a man's arm, then as his leg, and at laſt thicker than his whole body. We ſaw diſtinctly, through this tranſparent body, the water, which roſe up with a kind of ſpiral motion; and it ſometimes diminiſhed a little of its thickneſs, and again reſumed the ſame; ſometimes widening at top, and ſometimes at bottom; exactly reſembling a gut filled with water, preſſed with the fingers, to make the fluid riſe, or fall; and I am well convinced, that this alteration in the ſpout was cauſed by the wind, which preſſed the cloud, and impelled it to give up its contents. After ſome time its bulk was ſo diminiſhed as to be no thicker than a man's arm again; and thus, ſwelling and diminiſhing, it at laſt became very ſmall. In the end, I obſerved the ſea which was raiſed about it to reſume its level by degrees, and the end of the canal that touched it to become as ſmall as if it had been tied round with a cord; and this continued till the light, ſtriking through the cloud, took away the view. I ſtill, however, continued to look, expecting that its parts would join again, as I had before ſeen in one of the others, in which the ſpout was more than once broken, and yet again came together; but I was diſappointed, for the ſpout appeared no more."

Many have been the ſolutions offered for this ſurprizing appearance. Mr. Buffon ſuppoſes the ſpout, here deſcribed, to proceed from the operation of fire, beneath the bed of the ſea; as the waters at the ſurface are thus ſeen agitated. However, the ſolution of Dr. Stuart is not diveſted of probability; who thinks it may be accounted for by ſuction, as in the application of a cupping-glaſs to the ſkin.

Wherever ſpouts of this kind are ſeen they are extremely dreaded by mariners; for if they happen to fall upon a ſhip they moſt commonly daſh it to the bottom. But, if the ſhip be large enough to ſuſtain the deluge, they are at leaſt ſure to deſtroy its ſails and rigging, and render it unfit for ſailing. It is ſaid that veſſels of any force uſually fire their guns at them, loaden with a bar of iron; and, if ſo happy as to ſtrike them, the water is inſtantly ſeen to fall from them, with a dreadful noiſe, though without any further miſchief.

I am at a loſs whether we ought to reckon theſe ſpouts called typhons; which are ſometimes ſeen at land, of the ſame kind with thoſe ſo often deſcribed by mariners, at ſea. as they ſeem to differ in ſeveral reſpects. That, for inſtance, obſerved at Hatfield, in Yorkſhire, in 1687, as it is deſcribed by the perſon who ſaw it, ſeems rather to have been a whirlwind than a water-ſpout. The ſeaſon in which it appeared was very dry, the weather extremely hot, and the air very cloudy. After the wind had blown for ſome time, with conſiderable force, and condenſed the black clouds one upon another, a great whirling of the air enſued; upon which the center of the clouds, every now and then, darted down, in the ſhape of a thick long black pipe; in which the relator could diſtinctly view a motion, like that of a ſcrew, continually ſcrewing up to itſelf, as it were, whatever it happened to touch. In its progreſs it moved ſlowly over a grove of young trees, which it violently bent, in a circular motion. Going forward to a barn, it in a minute ſtript it of all the thatch, and filled the whole air with the ſame. As it came near the relator, he perceived that its blackneſs proceeded from a gyration of the clouds, by contrary winds, meeting in a point, or a center; and where the greateſt force was exerted, there darting down, like an Archimedes's ſcrew, to ſuck up all that came in its way. Another which he ſaw, ſome time after, was attended with ſtill more terrible effects; levelling, or tearing up great oak trees, catching up the birds in its vortex, and daſhing them againſt the ground. In this manner it proceeded, with an audible whirling noiſe, like that of a mill; and, at length, diſſolved, after having done much miſchief.

But we muſt ſtill continue to ſuſpend our aſſent as to the nature even of theſe land ſpouts; ſince they have been ſometimes found to drop, in a great column of water, at once upon the earth, and produce an inſtant inundation Phil. Tranſ. vol. iv, p. 2, 108. , which could not readily have happened had they been cauſed by the gyration of a whirlwind only. Indeed, every conjecture, regarding theſe meteors, ſeems to me entirely unſatisfactory. They ſometimes appear in the calmeſt weather at ſea, of which I have been an eye-witneſs; and, therefore, theſe are not cauſed by a whirlwind. They are always capped by a cloud; and, therefore, are not likely to proceed from fires at the bottom. They change place; and, therefore, ſuction ſeems impracticable. In ſhort, we ſtill want facts, upon which to build a rational theory; and, inſtead of knowledge, we muſt be contented with admiration. To be well acquainted with the appearances of Nature, even though we are ignorant of their cauſes, often conſtitutes the moſt uſeful wiſdom.

HAVING thus gone through a particular deſcription of the earth, let us now pauſe for a moment, to contemplate the great picture before us. The univerſe may be conſidered as the palace in which the Deity reſides; and this earth as one of its apartments. In this, all the meaner races of animated nature mechanically obey him; and ſtand ready to execute his commands, without heſitation. Man alone is found refractory; he is the only being endued with a power of contradicting theſe mandates. The Deity was pleaſed to exert ſuperior power in creating him a ſuperior being; a being endued with a choice of good and evil; and capable, in ſome meaſure, of co-operating with his own intentions. Man, therefore, may be conſidered as a limited creature, endued with powers imitative of thoſe reſiding in the Deity. He is thrown into a world that ſtands in need of his help; and has been granted a power of producing harmony from partial confuſion.

If, therefore, we conſider the earth as allotted for our habitation, we ſhall find, that much has been given us to enjoy, and much to amend; that we have ample reaſons for our gratitude, and ſtill more for our induſtry. In thoſe great outlines of nature, to which art cannot reach, and where our greateſt efforts muſt have been ineffectual, God himſelf has finiſhed theſe with amazing grandeur and beauty. Our beneficent Father has conſidered theſe parts of nature as peculiarly his own; as parts which no creature could have ſkill or ſtrength to amend: and therefore, made them incapable of alteration, or of more perfect regularity. The heavens, and the firmament, ſhew the wiſdom, and the glory of the Workman. Aſtronomers, who are beſt ſkilled in the ſymmetry of ſyſtems, can find nothing there that they can alter for the better. God made theſe perfect, becauſe no ſubordinate being could correct their defects.

When, therefore, we ſurvey nature on this ſide, nothing can be more ſplendid, more correct, or amazing. We there behold a Deity reſiding in the midſt of an univerſe, infinitely extended every way, animating all, and cheering the vacuity with his preſence! We behold an immenſe and ſhapeleſs maſs of matter, formed into worlds by his power, and diſperſed at intervals, to which even the imagination cannot travel! In this great theatre of his glory, a thouſand ſuns, like our own, animate their reſpective ſyſtems, appearing and vaniſhing at divine command. We behold our own bright luminary, fixed in the center of its ſyſtem, wheeling its planets in times proportioned to their diſtances, and at once diſpenſing light, heat, and action. The earth alſo is ſeen with its twofold motion; producing, by the one, the change of ſeaſons; and, by the other, the grateful viciſſitudes of day and night. With what ſilent magnificence is all this performed! with what ſeeming eaſe! The works of art are exerted with interrupted force; and their noiſy progreſs diſcovers the obſtructions they receive: but the earth, with a ſilent ſteady rotation, ſucceſſively preſents every part of its boſom to the ſun; at once imbibing nouriſhment and light from that parent of vegetation and fertility.

But not only proviſions of heat and light are thus ſupplied, but its whole ſurface is covered with a tranſparent atmoſphere, that turns with its motion, and guards it from external injury. The rays of the ſun are thus broken into a genial warmth; and, while the ſurface is aſſiſted, a gentle heat is produced in the bowels of the earth, which contributes to cover it with verdure. Waters alſo are ſupplied in healthful abundance, to ſupport life, and aſſiſt vegetation. Mountains ariſe, to diverſify the proſpect, and give a current to the ſtream. Seas extend from one continent to the other, repleniſhed with animals, that may be turned to human ſupport; and alſo ſerving to enrich the earth with a ſufficiency of vapour. Breezes fly along the ſurface of the fields, to promote health and vegetation. The coolneſs of the evening invites to reſt; and the freſhneſs of the morning renews for labour.

Such are the delights of the habitation that has been aſſigned to man; without any one of theſe, he muſt have been wretched; and none of theſe could his own induſtry have ſupplied. But while many of his wants are thus kindly furniſhed, on the one hand, there are numberleſs inconveniencies to excite his induſtry on the other. This habitation, though provided with all the conveniencies of air, paſturage, and water, is but a deſert place, without human cultivation. The loweſt animal finds more conveniencies in the wilds of nature, than he who boaſts himſelf their lord. The whirlwind, the inundation, and all the aſperities of the air, are peculiarly terrible to man, who knows their conſequences, and, at a diſtance, dreads their approach. The earth itſelf, where human art has not pervaded, puts on a frightful gloomy appearance. The foreſts are dark and tangled; the meadows over-grown with rank weeds; and the brooks ſtray without a determined channel. Nature, that has been kind to every lower order of beings, has been quite neglectful with regard to him; to the ſavage uncontriving man the earth is an abode of deſolation, where his ſhelter is inſufficient, and his food precarious.

A world thus furniſhed with advantages on one ſide, and inconveniences on the other, is the proper abode of reaſon, is the fitteſt to exerciſe the induſtry of a free and a thinking creature. Theſe evils, which art can remedy, and preſcience guard againſt, are a proper call for the exertion of his faculties; and they tend ſtill more to aſſimilate him to his Creator. God beholds, with pleaſure, that being which he has made, converting the wretchedneſs of his natural ſituation into a theatre of triumph; bringing all the headlong tribes of nature into ſubjection to his will; and producing that order and uniformity upon earth, of which his own heavenly fabric is ſo bright an example.