affrights a province, earthquakes have laid whole kingdoms in ruin.

Philosophers have taken some pains to distinguish between the various kinds of earthquakes, such as the tremulous, the pulsative, 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 à 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 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 compressed, 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, 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 perator in either.

Some philosophers, however, have been willing to give the air as great a share in producing these terrible effects 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 inflammable 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 their way, and so find a new solution. These only allow but just heat enough to produce the most dreadful phenomena, and, backing their assertions with long calculations, give theory an air of demonstration. Mr. Amontons has been particularly sparing of the internal heat in this respect; and has shown, 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 imaginary 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 fortythree thousand five hundred and twenty-eight fathom below the surface of the earth, becomes almost as heavy as quicksilver. This, however, is but a very slight depth in comparison of the distance to the centre, and is scarce a seventieth part of the way. The air, therefore, at the centre, 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 centre. 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: a heat, therefore, which at the surface of the earth would have produced but a slight expansive force, must at the centre produce one very extraordinary, and, in short, be perfectly irresistible. Hence this force may, 'with great ease, produce earthquakes; and, if increased, 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 gene

rally produce nothing; for, as I have ever observed, increased 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 som 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 a history of opinions instead of facts, some have ascribed them to electricity, and some to the same causes that produce thunder.

To con

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. ceive this distinctly, let us suppose at some vast distance under the earth large quantities of inflammable 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: instantly 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 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, 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 the lake, although it shook the greatest part of Italy. In another place 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 Etruscan 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 Emilian 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 time 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 more particularly described in history is that of the year 1693, the damages of which were chiefly felt in Sicily, but its motion perceived in France, Germany, and England. It extended to a circumference of 2,600 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. 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 suddenly began to roar, and Etna to send forth great spires of flame; 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 nearly 19,000 of the inhabitants of Sicily perished in the ruins. Catanea, to which the describer was travelling, seemed the principal scene of ruin; its site 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 PortRoyal, and sunk the houses in a gulf forty fathoms deep. It was attended with a hollow rumbling noise like that of thunder, and in less than a minute three-parts of the houses and their inhabitants were all quite sunk 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, continuing 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 instantly crushed them 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 crash 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 vere swallowed up; houses, people, trees, shared one universal ruin, and in their places appeared great pools

of water, which, when driea up oy the sun, e only a plain of barren sand, without any vestige of former inhabitants. Most of the rivers during the earthquake were stopped by the falling in of the mountains; and it was not till after some time that they made themselves new channels. The mountains seemed particularl 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 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 Kircher, as it happened while he was on his journey to visit Mount Etna, 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, we launched, on the 24th 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 Euphæmia, in Calabria, where we had some business to transact, and where we designed to tarry some time. However, Providence seemed willing to cross our designs, for we were obliged to continue for three days at Pelorus, on 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 gulf of Charybdis, which we approached, seemed whirled round in such a manner as to form a vast hollow, verging to a point in the centre. Proceeding onward, and turning my eyes to Etna, I saw it cast forth large volumes of smoke, of mountainous size, 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 agitation. My surprise was still increased 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 Tropæa, happy and thankful for having escaped the threatening dangers of the sea.

But our triumph on land was of short duration; for we had scarce arrived at the Jesuits' College in that city, when our ears were stunned with a 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 meantime, the universal ruin round me redoubled ny

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 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 coast, and the next day arrived at 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 put up, dashed to the ground-burying all its inhabitants beneath its ruins.

"In this manner, proceeding onward in our little vessel, finding no safety on 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 Tropea 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 found 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 Euphemia, which lay within sight. In the meantime, 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 surprised us, as the weather was so very serene. We waited, therefore, till the cloud was dispersed; 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 seemingly stupified with terror. Of him, therefore, we inquired concerning the fate of the city, but he could not be induced to give us an answer. We intreated him with every expression of tenderness and pity to tell us; but his senses were quite wrapt up in contemplation of the danger he had escaped. We offered him some victuals, but he seemed to lothe 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 Euphemia! 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 a 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 on land. This agitation is only a similar effect produced on the waters with that on land, and may be called, for the sake of perspicuity, a “seaquake;" and this, also, is produced by volcanoes.

A spouting 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 water.

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 of the same day. This arises from the great shock being given to the earth at one place, and which, 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 on the shore 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 phenomena 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. 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.

CHAP. XI.

OF THE APPEARANCE OF NEW ISLANDS AND TRACTS, AND OF THE DISAPPEARING OF OTHERS.

Hitherto we have taken a survey only of the evils which are produced by subterranean fires, but we have mentioned nothing of the benefits they may possibly produce. They may be of use in warming and cherishing the ground, in promoting vegetation, and giving a more exquisite flavour to the productions of the earth. The imagination of a person who has never been out of our own mild region, can scarcely reach to that luxuriant beauty with which all Nature appears clothed in those very countries that we have just now described as desolated by earthquakes, and undermined by subterranean fires. It must be granted, therefore, that though in those regions they have a greater share in the dangers, they have also a larger proportion in the benefits of Nature.

But there is another advantage arising from subterranean fires which, though hitherto disregarded by man, yet may one day become serviceable to him; I mean, that while they are found to swallow up cities and plains in one place, they are also known to form promontories and islands in another. We have many instances of islands being thus formed in the midst of the sea, which, though for a long time barren, have afterwards become fruitful seats of happiness and industry.

New islands are formed in two ways-either suddenly, by the action of subterraneons fires, or more slowly, by the deposition of mud carried down by rivers, and stopt by some accident. With respect particularly to the first, ancient historians and modern travellers give us such accounts as we can have no room to doubt of. Seneca assures us, that in his time the island of Therasia appeared unexpectdly to some mariners, as they were employed in another pursuit, Pliny states that thirteen islands in the Mediterranean appeared at once emerging from the water-the cause of which he ascribes rather to the retiring of the sea in those parts than to any subterraneous elevation. However, he mentions the island of Hiera, near that of Therasia, as formed by subterraneous explosions; and adds to his list several others, formed in the same manner, in one of which he relates that fish were found in great abundance, and that all those who eat of them died shortly after.

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On the twenty-fourth of May, in the year 1707, a slight earthquake was perceived at Santorin; and the day following, at sun-rising, an object was seen by the inhabitants of that island, at two or three miles distance at sea, which appeared like a floating rock. Some per sons, desirous either of gain or incited by curiosity, went there, and found, even while they stood upon this rock, that it seemed to rise beneath their feet. They perceived, also, that its surface was covered with pumicestones and oysters, which it had raised from the bottom. Every day after, until the fourteenth of June, this rock seemed considerably to increase; and then was found to be half a mile round, and thirty feet above the sea. The earth of which it was composed seemed whitish, with a small proportion of clay. Soon after this the

sea again appeared troubled, and steams arose which were very offensive to the inhabitants of Santorin. But on the sixteenth of the succeeding month, seventeen or eighteen rocks more were seen to rise out of the sea, and at length to join together. All this was accompanied with the most terrible noise, and fires that proceeded from the island that was newly formed. The whole mass, however, of all this new-formed earth, uniting, increased every day, both in height and breadth, and, by the force of its explosions, cast forth rocks to seven miles distance. This continued to bear the same dreadful appearances till the month of November in the same year; and it is at present a volcano which sometimes renews its explosions. It is about three miles in circumference, and more than from thirty-five to forty feet high."

A new island was found, in the year 1720, near that of Tercera, near the continent of Africa, by the same causes. In the beginning of December, at night, there was a terrible earthquake at that place, and the top of a new island appeared, which cast forth smoke in vast quantities. The pilot of a ship, who approached it, sounded on one side of this island, and could not find ground at sixty fathoms. At the other side the sea was totally tinged of a different colour, exhibiting a mixture of white, blue, and green, and was very shallow. This island, on its first appearance, was larger than it is at present-for it has, since that time, sunk in such a manner as to be scarce above water.

A traveller, whom these appearances could not avoid affecting, speaks of them in this manner:-" What can be more surprising than to see fire not only break out of the bowels of the earth, but also make itself a passage through the waters of the sea! What can be more extraordinary or foreign to our common notion of things, than to see the bottom of the sea rise up into a mountain above the water, and become so firm an island as to be able to resist the violence of the greatest storms! I know that subterraneous fires, when pent in a narrow passage, are able to raise up a mass of earth as large as an island; but that this should be done in so regular and exact a manner, that the water of the sea should not be able to penetrate and extinguish those firesthat after having made so many passages they should retain force enough to raise the earth-and, in fine, after having been extinguished, that the mass of earth should not fall down, or sink again with its own weight, but still remain in a manner suspended over the great arch below!-this is what to me seems more surprising than anything that has been related of Mount Etna, Vesuvius, or any other volcano."

Such are his sentiments; however, there are few of these appearances any way more extraordinary than those attending volcanoes and earthquakes in general We are not more to be surprised that inflammable sub. stances should be found beneath the bottom of the sea, than at similar depths on land. These have all the force of fire giving expansion to air, and tending to raise the earth at the bottom of the sea, till it at length heaves above water. These marine volcanoes are not so frequent; for, if we may judge of the usual procedure of Nature, it must very often happen, before the bottom of the sea is elevated above the surface, a chasm is opened in it, and then the water pressing in, extinguishes the volcano before it has time to produce its effects. This extinction, however, is not effected without very great resistance from the fire beneath. The water, upon dashing into the cavern, is very probably at first ejected back with great violence; and thus some of those amazing water-spouts are seen, which have so often astonished the mariner and excited curiosity. But of these in their place.

Besides the production of those islands by the action of fire, there are others, as was said, produced by rivers or seas carrying mud, earth, and such like substances,