Front matter (continued 2)

It is to these inequalities at the bottom of the sea, we must attribute the origin of currents, for if the bottom was equal and level, there would be no other current than the general motion from east to west, and a few others which might be caused by the action of the winds; but a certain proof that most currents are produced by the flux and reflux, and directed by the inequalities at the bottom of the sea, is, that they regularly follow the tides, and change their direction at each ebb and flow. See Pietra della Valle on the subject of the currents of the gulph of Cambay, and the accounts of all navigators, who unanimously assert that in those parts where the flux and reflux of the sea is the most violent, the currents are also most rapid.

Therefore it cannot be doubted but that the tides produce currents whose direction always answers that of the opposite hills and all mountains between which they flow. Currents produced by winds, also follow the direction of those hills which are under the water, seldom running opposite to the wind which produces them, any more than those which are occasioned by the tides follow the direction of their original cause.

To give a clear idea of the productions of currents, we shall first observe they are to be met with in every sea; that some are rapid, and others slow; that some are of great extent, both in length and breadth, and others short and narrow; that the same cause, whether the wind or tides, which produces these currents, frequently gives to each of them a velocity and direction very different; that a north wind, for example, which should give the water one general motion towards the south, on the contrary, produces a number of currents, separated from each other, and very different both in extent and direction; some flowing towards the south, others south-east, and others south-west; some are very rapid, others slow; some long and broad, others short and narrow; in fact, their motions are so various that we have no idea left of their original cause. When a contrary wind succeeds, all these currents take an opposite course, and follow in a contrary direction, precisely in the same manner as would be the case upon land between two opposite and adjacent hills, provided it was covered with water, as is seen at the Maldiva and all the islands of the Indian seas, where the currents run, and the winds blow, for six months in a contrary direction. The same remark has been made on currents between shoals and sandbanks. In general all currents, whether caused by the motion of flux or reflux, or the action by the wind; have the same extent and direction throughout their whole course, yet differ from each other in most respects, which can proceed only from the inequalities of the hills, mountains, and vallies, at the bottom of the sea, it being certain that the current between two islands follows the direction of the coasts; and the same is observable between banks of sand, shoals, &c. we must, therefore, look on the hills and mountains of the bottom of the sea as banks which direct the current; and hence a current is a river, the breadth of which is determined by that of the valley through which it flows: its rapidity depends on the force which produces it, combined with the breadth, of the interval through which it must pass: and its direction is traced by the position of the hills and inequalities between which it must take its course.

We shall now give a reason for the singular correspondence between the angles of mountains and hills, which are to be met with in every part of the world. We have already remarked that when a river, &c. forms an elbow, one of the borders forms on one side a projection inland, and the other forms a point from land, and that through all the sinuosities of their course this correspondence is always found. This fact is founded on the laws of hydrostatics. It would be easy to demonstrate the cause of this effect; but it is sufficient that it is general and universally known, and that all the world may be convinced of it by their own eyes, that when the banks of a river form a projection inland to the left hand, the other shore forms a projection from land to the right.

Hence the currents of the sea must be looked upon as great rivers, subject to the some laws as those on land, and will, like them, form in the extent of their course many sinuosities, whose projections or angles will correspond; and as the banks of currents are hills and mountains, above or below the surface of the water, they will have given these eminences the same form as is remarked on the shores of rivers; therefore we must not be astonished that our hills and mountains, which have been formerly covered by the sea, and formed by the sediments which the waters have left, should, by the motion of its currents, have taken this regular figure, and all the angles are alternately opposite; they have been the shores of the currents or rivers of the sea, and have therefore necessarily taken a figure and direction similar to those of the shores of the rivers of the earth.

This alone, independent of the other proofs we have given, would be sufficient to evince that the earth of our continent and islands have been covered with waters of the ocean, and doubtless throws great light upon the Theory which I have endeavoured to prove well founded; for it was not sufficient to have proved that the strata of the earth were formed by the sediments of the sea; that the mountains were elevated by the successive accumulation of such sediments; and that they were composed of shells and other marine productions; but it required also a reason why the angles of mountains so exactly correspond; this could only be done by an investigation into the real cause, which had not hitherto been attempted, and which, being united with the rest, forms a body of proofs as complete as may be had in physics, and establishes my Theory to be founded on facts, independent of all hypothesis.

The principal currents of the ocean are those observed in the Atlantic Sea, near Guinea. They extend from Cape Verd to the Bay of Fernandes. Their motion is from west to east; that is contrary to the general motion of the sea. These currents are so rapid that vessels sail in two days from Moura to Rio de Benin, a course of 150 leagues; but they require six or seven weeks to return; nor would it be possible to get out of these climates if advantage was not taken of the tempestuous winds which suddenly rise in them; but there are entire seasons during which vessels cannot stir, the sea being continually calm, excepting what arises from the currents, which is always directed towards the coasts, and never extend more than 20 leagues from shore. Near Sumatra there are rapid currents, which flow from south to north, and which probably formed the gulph at Malacca. There are also considerable currents between Java and Magellan, the Cape of Good Hope, and the island of Madagascar, especially on the coast of Africa, between Natal and the Cape. In the Pacific Sea, on the coast of Peru, and the rest of America, the sea moves from south to north, and a south wind continually blowing there seems to be the cause. The like motion is observed on the coasts of Brazil; from Cape St. Augustine to the Antilles; from the mouth of the Manilla strait to the Philippine islands; and in the port of Kubuxiu at Japan[D].

There are violent currents in the sea adjacent to the Maldivian islands; and between those islands these currents flow, as already observed, constantly for six months from east to west, and during the other six months they follow the direction of the monsoons, and it is probable they are produced by those winds.

We speak here only of currents, whose extent and rapidity are very considerable, for in every sea there are an infinity of currents, though of no great importance. The flux and reflux, the winds, and all other causes which agitate the waters, produce currents, more or less perceptible, in different parts. We have observed that the bottom of the sea, like the surface of the earth, is overspread with mountains intersected with inequalities and divided by banks of sand. In all mountainous places currents will be violent; in all places where the bottom of the sea is level they will be almost imperceptible; the rapidity of the current will increase in proportion to the obstacles the water meets with, or rather to the contraction of the spaces through which they incline to pass. Between two chains of mountains the current will be so much the stronger as the mountains are near. It will be the same between two banks of sand, or two neighbouring islands. It is also remarked in the Indian ocean, which is divided with an infinity of islands and banks, there are rapid currents throughout, which render the navigation of that sea dangerous.

It is not inequalities at the bottom of the sea alone which form currents, but the coasts themselves have a similar effect, as the water is repelled at greater or lesser distances: this repulsion of the waters is a kind of current which circumstances can render continual and violent; the oblique position of a coast, the vicinity of a bay, or of some great river, a promontory; in one word, every particular obstacle which opposes the general motion, will always produce a current. Now, as nothing is more irregular than the bottom and borders of the sea, we must cease from being surprised at the great number of currents which every where appear.

All currents have a determinate breadth, which depends on that of the interval between the two eminences which serves it for a bed. The currents flow into the sea as rivers flow on land, and they produce similar effects. They form their bed, and give to eminences corresponding angles. In one word, it is these currents which hollowed our vallies, formed our mountains, and gave to the surface of the earth, when it was under water, the form it now retains.

If any doubt of the correspondence of the angles of mountains remains, I appeal to the sight of every man who makes the observation. Every traveller, with the smallest attention, will perceive that the opposite sides of a hill exactly correspond. Whenever the hills to the right of the valley form a projection, those opposite recede to the left. These hills have also nearly the same elevation, and it is very rare to see any great inequality of height in the two hills separated by a valley. I can assert, that the more I have looked on the circumference and heights of hills, the more I have been convinced of the correspondence of the angles, and of the resemblance they have with the beds and borders of rivers; and it is by reiterated observations on this surprising regularity and resemblance that my first ideas of this Theory of the Earth arose. Let us add to these observations that of the parallel and horizontal situation of the strata, that of the shells being dispersed throughout the earth, and incorporated in every matter; and it must be admitted, that on a subject like this we cannot have a greater degree of probability.

ARTICLE XIV.

OF REGULAR WINDS.

Nothing can appear more irregular and variable than the force and direction of winds in our climates; but there are countries where this irregularity is not so great, and others where the winds constantly blow in one direction, and with almost the same degree of strength.

Although the motion of the air depends on a great number of causes, there are nevertheless principal ones, of which it is difficult to estimate the effects, because of the modifications from secondary causes. The most powerful cause is the heat of the sun, which produces successively a considerable rarefaction in different parts of the atmosphere, and gives rise to an east wind that constantly blows between the tropics, where rarefaction is the greatest.

The force of the sun's attraction, and even that of the moon on the atmosphere, are inconsiderable in comparison with that just mentioned; it is true, this force produces in the air a motion similar to that of the flux and reflux in the sea, yet it must not be supposed that the air, because it has a spring, and is 800 times lighter than water, receives, by the action of the moon, a more considerable motion than that of the waters of the sea; for the distance of the moon being the same, a sea of any fluid matter will have nearly the same motion, because the force which produces it penetrates the matter, and is proportional to its quantity; thus a sea of water, air, or quicksilver, would elevate itself nearly to the same height, by the action of the sun and moon; hence we see that the the influence of the planets in the atmosphere is not considerable, and although it must cause a slight motion of the air from east to west, this motion is insensible in comparison with that produced by the heat of the sun; but as the rarefaction will be always greatest when the sun is at the zenith, the current of air must follow the sun, and form a constant wind from east to west. This wind blows continually over the sea in the torrid zone, and in most parts of the land between the tropics; it is this wind we feel at the sun's rising; and in general the east winds are more frequent and impetuous than the west; this general wind from east to west extends even beyond the tropics, and blows so constantly in the Pacific Sea, that vessels which sail from Acapulco to the Philippines, perform their voyage, which is more than 2700 leagues, without any risque, and almost without any need of directing their course. In the Atlantic, between Africa and Brazil, this wind is also constant: it is felt also between the Philippines and Africa, but not in so constant a manner, by reason of the islands, and different obstacles that are met with in that sea; for during the months of January, February, March, and April, it blows between the Mozambique coast and India, but during the other months, it gives place to different winds: and although this east wind is less felt on the coasts than in the open sea, and still less in the middle of continents than on the coasts; nevertheless there are places where it blows almost continually, as on the east coasts of Brazil, on the coasts of Loango, in Africa, &c.

This east wind continually blowing under the line, is the cause, that sailing from Europe to America, the course of the vessel is directed from the north to the south, along the coasts of Spain and Africa, to within 20 degrees of the equator, where this east wind is met with, which carries them directly to the coasts of America. The voyage from Acapulco to the Philippine islands, is made in two months by the favour of this east wind: but the return from them to Acapulco is longer and more difficult. At 28 or 30 degrees on this coast from the line, the western wind is nearly as constant, which is the reason that vessels returning from the East Indies to Europe, do not follow the same track as in going; those from New Spain sail north along the coasts till they arrive at the Havannah, and from thence they continue northward, until they meet with the westerly winds which carry them to the Azores and afterwards to Spain. So likewise in the South Sea, those which return from the Philippines, or China, to Peru, or Mexico, sail north as far as Japan, and navigate under that parallel to a certain distance from California, from whence, coasting along New Spain, they arrive at Acapulco. These winds do not always blow from one point, but in general from the south-east from April to November, and from the north-east from November to April.

The east wind, by its action, increases the general motion of the sea from east to west; it also produces currents which are constant, some flowing from east to west, others from west to east; and from the east to the south-west or north-west, following the direction of the eminencies and chains of mountains at the bottom of the sea, the vallies that divide them serving as channels to these currents. The alternative winds which blow sometimes from the east, and sometimes from the south, produce also currents which change their direction at the same time with these winds.

The winds which blow continually for some months, are generally followed by contrary winds, and therefore mariners are obliged to wait for that which is favourable to their voyage. When these winds change, a calm or dangerous tempest generally ensues, and which continues for several days, sometimes a month, and has been known for more than two.

These general winds caused by the rarefaction of the atmosphere, are differently combined and modified by different causes in different climates. In that part of the Atlantic, under the temperate zone, the north wind blows almost constantly during the months of October, November, December, and January, which makes those months the most favourable to embark from Europe to India, in order to pass the line by the aid of these winds; and it is known by experience, that ships which quit Europe in the month of March frequently do not arrive sooner at Brazil than those which sail in the October following. The north wind almost continually reigns during winter in Nova Zembla, and other northern coasts. The south wind blows during the month of July at Cape de Verd, when the rainy season, or winter of these climates sets in. At the Cape of Good Hope the north-west wind blows during the month of September. At Patna, in the East Indies, the north-west wind blows during the months of November, December, and January, and produces heavy rains; but the east wind blows during the other nine months. In the Indian ocean, between Africa and India, as far as the Malacca islands, the monsoons reign from east to west from January to the beginning of June, the west winds begin in the months of August or September; during the interval of June and July, there are dreadful tempests generally from the north winds; but on the coasts these winds vary much more than in the open sea.

In the kingdom of Guzarat, and on the coasts of the neighbouring sea, the north winds blow from March till September, and during the other months south winds almost always reign. The Dutch, to return from Java, generally set sail in the month of January or February, when they have the assistance of an easterly wind which is felt as far as the 18th degree of South latitude; afterwards they meet with the south winds which carry them to St. Helena[E].

There are regular winds produced by the melting of snows, which the ancient Greeks have noticed. During summer a north-east wind, and in winter one from the south-east, were noticed in Greece, Thrace, Macedonia, the Egean sea, and as far as Egypt and Africa; the same kind of winds have been remarked at Congo, at Guzarat, and at the extremity of Africa, which are all produced by the melting of the snows. The flux and reflux of the sea also produce regular winds which remain only a few hours, and in many places winds are observed to blow from the land during night, and from the sea during the day, as on the coasts of New Spain, Congo, the Havannah, &c.

The north winds are pretty regular in the polar circles; but the nearer we approach the equator, the weaker they become: a circumstance equally common to the two poles.

In the Atlantic and Ethiopian ocean within the tropics there is an east wind which blows all the year without any considerable variation, excepting some few small places, where it changes according to circumstances and the position of the coasts. First, near the coasts of Africa, having passed the Canary islands, about the 28th degree of north latitude, a fresh wind blowing from the north-east or north-north-east, is sure to be met with; this wind accompanies the vessels to the 10th degree of the same latitude; about 100 leagues from the coast of Guinea; where at the 4th degree north latitude they meet with calms and tornadoes. Secondly, in going to America by the Caribbee islands, this wind is found to veer more and more to the east, in proportion as they approach the coast. Thirdly, the limits of these variable winds in the Atlantic, are greater on the American coasts than on those of Africa. A south or south-west wind blows continually all along the coast of Guinea for a space of 500 leagues from Sierra Leona to the island of St. Thomas; the narrowest part of that sea is from Guinea to Brazil, being not more than 500 leagues across. Nevertheless, ships which sail from Guinea do not direct their course straight to Brazil, especially when they sail in the months of July and August, for the purpose of taking advantage of the south-east winds which reign at that time[F].

In the Mediterranean the east wind blows from the land in the evening at the sun's setting, and the west wind from the sea at its rising in the morning. The south wind, which is commonly attended with rains, and which generally blows at Paris, Burgundy and Champagne about the beginning of November, gives place to mild and temperate breezes that produce that fair weather vulgarly called the summer of St. Martin's.

Doctor Lister pretends that the east wind that blows between the tropics all the year, is produced by the vapour of the plant called sea lentil, which is extremely plentiful in those climates, and that the difference of the winds on the land proceeds only from the different disposition of the trees and forests; and he very seriously gives this ridiculous imagination for a cause of the wind, by saying, that at noon the wind is strongest because the plants are hotter and respire the most, and that it blows from east to west, because all plants, somewhat like sun-flowers, turn and respire with the sun.

Other authors have mentioned the motion of the earth on its axis as the cause of this wind: this opinion is specious; and every person, even but little initiated in mechanics, must comprehend, that no fluid which surrounds the earth can have a particular motion from the rotation of the globe; that the air can have no other motion than that of the earth, and that all turning together at one time, this rotative motion must be as insensible in the atmosphere, as it is on the surface of the earth.

The principal cause of the winds, as we have observed, is the heat of the sun; on this subject we refer to Halley's Treatise in Phil. Trans. All causes which occasion rarefaction or condensation in the air will produce winds, whose directions will be opposite to the places where is the greatest rarefaction or condensation.

The pressure of the clouds, the exhalations of the earth, the inflammation of meteors, &c. are causes which also produce considerable agitations in the atmosphere. Each of these causes combining in different manners, produces different effects. It appears to me, therefore, a vain attempt to assign a theory of the winds, for which reason I shall limit myself to the study of their history.

If we could have a course of observations on the direction, power, and variation of the wind in different climates; if this course of observations was exact and extensive enough for us to perceive the result of these vicissitudes of the air in every country, we should arrive at that degree of knowledge, from which at present we are very remote; but a short time has passed since meteorological observations have been made, and possibly much more will pass before we know how to employ the results of them, although they are the only means that we have to arrive at some positive knowledge on this subject.

On the sea the winds are more regular than on land, because the sea is an open space, in which nothing opposes their direction, while on land mountains, forests, and towns, form obstacles which change their course. Winds reflected by the mountains are often as impetuous as in their first direction: these winds are very irregular, because their course depends on the size, height, and situation of the mountains which reflect them. The sea winds blow with greater power than the land winds, are not so variable, and last longer. Land winds, however violent, have moments of remission, and sometimes of quiet, but at sea their currents are constant and continual, without any interruption.

In general on the sea the east wind, and those which come from the poles, are stronger than the west and those which proceed from the equator. On the land the west and south winds are more or less violent, according to the situation of the climates. In spring and autumn all winds are more violent than in summer or winter, and for these reasons; first, in spring and autumn are the highest tides, and consequently the winds that these tides produce are most violent at those seasons; secondly, the motion which the action of the sun and moon produce in the air is also greater in the season of the equinoxes; thirdly, the melting of the snows in spring, and the condensation of the vapours that the sun raises during summer, which refall in plentiful rains during autumn, produce, or at least increase the wind; fourthly, the change from heat to cold, or from cold to heat, cannot be made without increasing and diminishing consequently the volume of air, which alone must produce very high winds.

Contrary currents are often observed in the air; some clouds move in one direction, while others, which are higher or lower, move in a directly opposite one; but this contrariety of motion does not remain, being commonly produced by the resistance of some large clouds that force the wind into another course, but which returns again as soon as the obstacle is dissipated.

The winds are more violent in mountainous places than in plains, and increase until we reach the common height of the clouds, that is to say, to about one quarter, or one third of a league perpendicular height; beyond that height the sky is generally serene, at least during the summer, and the wind gradually diminishing. It is even asserted to be quite insensible at the summit of the highest mountains; but these summits being covered with snow and ice, it is natural to suppose that this region of air is agitated by the wind when the snow falls, and only during summer that the winds are not to be perceived. In summer the light vapours which are raised above the summit of these mountains fall in the form of dew, whereas in winter they condense and fall in snow or ice, which in winter may raise considerable winds, even at that height.

A current of air increases in velocity where the space of its passage is straitened: the same wind which was moderate in an open plain becomes violent in passing through a narrow passage in a mountain, or between two lofty buildings; and its most violent action is at the top of these structures or mountains, for air being compressed by these obstacles, its density and mass becomes increased, and as the velocity remains, the force or momentum of the wind naturally becomes much stronger. This is the cause that near a church or castle the winds seem to be stronger than at a distance from them. I have often remarked, that the wind reflected from a lone building is more violent than the direct wind which produced it. This can only be occasioned by the impelled air being compressed against the building, and by that means adds to its force.

The density of the air being greatest at the surface of the earth, we might be led to imagine that the greatest action of the wind should be there also; and I indeed think this is really the case when the sky is serene; but when it is covered with clouds, the most violent action of the wind is at the height of these clouds, which generally fall in rain or snow. The strength of the wind, therefore, must be estimated, not only by the velocity, but also by the density of the air; for it will often happen that one wind, which shall have no more velocity than another, will, nevertheless, root up trees and overturn buildings, only from the air impelled by this wind being denser; and this evinces the imperfection of the machines invented to measure the velocity of the wind.

Particular winds, whether direct or reflected, are more violent than general ones. The interrupted action of land-winds depends on the compression of the air, which renders each blast much more violent than if the wind blowed uniformly. A strong continued wind never occasions such disasters as the rage of those produce which blow, as it were, by fits; but we shall give examples thereof in the following article.

We may consider the winds, and their directions, under general points of view, from which possibly we may derive useful instructions; for example, we might divide the winds into zones. The east wind, which extends to about 25 or 30 degrees on each side the equator, exerts its action round the globe in the torrid zone; the north wind almost always as constantly in the frigid zones. Therefore it may be said that the east wind occupies the torrid zone, the north wind the frigid zones, and with respect to the temperate zone, the winds which reign there are merely currents of air produced by these two winds, whose direction tends to the eastern points. With respect to the westerly winds, which often reign in the temperate zones, both in the Pacific and Atlantic Oceans, they may be regarded as winds reflected by the lands of Asia and America, deriving their origin from the east and north winds.

Although we have said that, generally speaking, the east winds reign around the globe to about 25 or 30 degrees on each side the equator, it is nevertheless certain, that in some parts they do not extend so far, and their direction is not always from east to west, for on this side the equator it is east-north-east, and beyond the equator it is east-south-east, and the further we remove from the equator the more the direction is oblique. The equator is the line under which the direction of the wind from east to west is the most exact; for example, in the Indian ocean, the general wind from east to west scarcely extends beyond 15 degrees. Sailing from Goa to the Cape of Good Hope this wind is not felt till we have past the equator; but after arriving at the 12th degree south latitude, it continues to the 28th degree. In the sea which divides Africa from America there is an interval from the 4th degree north latitude to the 10th or 11th degree south, where this general wind is not perceivable; but beyond the 10th or 11th degree it reigns as far as the 30th.

There is also much exception with regard to the trade winds, whose motion is alternative. Some remain a longer or a shorter time, others extend to greater or less distances; others are more or less regular, and more or less violent. Varenius speaks thus of a principal phenomena of these winds. "In the ocean between Africa and India, as far as the Malaccas, the east winds begin to reign in January and last to the beginning of June; in August or September the west winds begin and continue during three or four months. In the interval of these monsoons, that is from the end of June to the beginning of August, there is no wind on that sea, but they have violent storms which come from the north.

"These winds are subject to the greatest variations near the land, for ships cannot depart from the Malabar coast, nor other western ports on the coasts of the peninsula of India, to sail to Africa, Arabia, or Persia, but from January to April or May; for from the end of May, and during the months of June, July, and August, there are such violent tempests from the north or north-east that ships are not able to keep the sea. On the other side of this peninsula, in the sea which bathes the Coromandel coast, these tempests are not known.

"To sail from Java, Ceylon, and many other places, to the Malacca islands, the month of September is the most proper time, because the west wind begins to blow in these parts; nevertheless, at 15 degrees south of the equator, we lose this west wind and meet with the general winds, which blow south-east. To sail from Cochin to Malacca they depart in March, because the west winds begin to blow at that time; therefore these westerly winds blow at different times in different parts of the Indian sea; and it is necessary to sail at different periods in going from Java to the Malaccas, from Cochin to Malacca, from Malacca to China, and from China to Japan.

"At Banda, the west winds finish at the end of March, calms reign during April, in May the east winds begin again with great violence. At Ceylon, the west winds begin about the middle of March, and remain till the beginning of October, when the east or rather north-east wind returns. At Madagascar, from the middle of April to the end of May, the north and north-west winds are constant; but in February and March, the east and south winds reign. From Madagascar to the Cape of Good Hope, the north and collateral winds blow during March and April. In the Gulph of Bengal, the south wind prevails after the 20th of April, before which time the south-west or north-west winds are predominant. The west winds are also violent in the sea of China, in June and July, which is likewise the most suitable season to go from China to Japan; but to return from Japan to China, February and March are preferred, because the east or north-east winds prevail.

"There are winds which may be regarded as peculiar to certain coasts; for example, the south wind is almost continually on the coasts of Chili and Peru; it begins at the 46th degree south latitude, and extends beyond Panama, which renders the voyage from Lima to Panama much easier performed than the return. The west wind blows continually on the Magellanic coasts, and in the straits of Le Maire. The north and north-west winds almost continually reign on the Malabar coast. The north-west wind is very frequent on the coast of Guinea. The westerly winds reign on the coasts of Japan, in the months of November and December."

The alternative, or periodical winds, which we have just been speaking of, are sea winds; but there are also land winds which are periodical, and return either at a certain season, or in certain days, or even at certain hours; for example, on the Malabar coast, from September to April a land wind blows from the eastern side; it generally commences at midnight, and finishes at noon, and is not felt beyond 12 or 15 leagues from the coast; and from noon till midnight a gentle wind blows from the west. On the coast of New Spain, in America, and on that of Congo, in Africa, land winds reign during the night, and sea winds during the day. At Jamaica the winds blow from all parts of the coast at once during the night, and therefore vessels cannot go in, nor depart from it with safety, but in the day time.

In winter the port of Cochin is not to be entered, nor can any vessel quit it, because the winds blow with such impetuosity, that ships cannot remain at sea; and besides the west winds, which blow with such fury, bring to the mouth of the river so great a quantity of sand as prevents the possibility of ships of any size from entering it during six months of the year; but the east winds which blow during the other six months repel these sands, and render the entrance of the river free. At the strait of Babelmandel there are south-east winds which reign throughout the season, and are always succeeded by north-east. At St. Domingo there are two different winds which regularly rise almost every day, the one a sea wind proceeding from the east, and commences at 10 o'clock in the morning; the other a land wind comes from the west, rises at six or seven o'clock in the evening, and remains all night. There are many other facts of this nature to be extracted from travellers, the knowledge of which might perhaps lead to a history of the winds, which would be a useful work equally to navigation and physics.

ARTICLE XV.

OF IRREGULAR WINDS, HURRICANES, AND OTHER PHENOMENA, CAUSED BY THE AGITATION OF THE SEA AND AIR.

The winds are more irregular on the land than on the sea, and in high places than in low. The mountains not only alter the direction of winds, but even produce some which are either constant or variable according to different causes. The melting of snow upon the summits of mountains, generally produces constant winds, which sometimes remain a considerable time; the vapours that are stopt by mountains accumulate there, and produce variable winds, very frequent in all climates: and there are as many variations in the motions of air, as there are inequalities on the surface of the earth. We can therefore give only examples, and relate circumstances which are attested; and as we are deficient in a course of observations on the variation of winds, and even of the seasons in different countries, we do not pretend to explain all the causes of these differences, but confine ourselves to those which appear the most probable.

In straits, on all projecting coasts, at the extremity of all promontories, peninsulas and capes, and in all narrow bays, storms are frequent; but without these there are some seas much more tempestuous than others. The Indian ocean, the Japan and the Magellan seas, that of the African coast beyond the Canaries, and on the other side towards the coast of Natal and the Red Sea, are very liable to storms. The Atlantic is more stormy than the ocean, which from its tranquillity is called the Pacific Sea; this sea, however, is not absolutely tranquil, except between the tropics, for the nearer we approach the poles, the more we are subject to variable winds, whose sudden changes are frequently the cause of tempests.

All continents are subject to variable winds, which often produce singular effects; in the kingdom of Cassimir, which is surrounded by the mountain of Caucasus, at the mountain Pirepinjale, extraordinary and sudden changes are experienced; we pass, in less than an hour's travelling, from summer to winter; at this place are two winds, a north and south, and which, according to Bernier, we successively feel in less than 200 feet distance from each other; the position of this mountain must be singular, and merit observation. In the peninsula of India, which is crossed from north to south by the mountains of Gate, it is winter on one side, and summer on the other at the same time. The like difference is met with on the two sides of Rozalgate Cape in Arabia; the sea to the north of the cape is perfectly tranquil, while in the south violent tempests are experienced. It is the same in the island of Ceylon; winter and high winds are experienced in the northern parts of the island, while in the southern there is fine summer weather. This contrariety of seasons at the same time not only happens in many parts of the Indian continent, but also in many islands; for example, at Cerem, a long island in the vicinage of Amboyna, they have winter in the northern part, and summer at the same time in the southern, and the interval that divides the two seasons is not above three or four leagues.

In Egypt they have a south wind in summer, so hot as to prevent respiration, and raises such great quantities of sand, that the sky seems covered with thick clouds; this sand is so fine, and driven with such force, that it penetrates even into the closest chests. When these winds last many days they cause epidemical diseases, which are often followed by a great mortality. It seldom rains in Egypt, nevertheless every year there are some days of rain in the months of December, January, and February. Thick mists are more frequent there than rain, especially in the environs of Cairo; these mists begin in November, and continue all the winter; and during the whole year there falls so plentiful a dew, even when the sky is serene, that it might be taken for a slight rain.

In Persia winter begins in November and lasts till March: the cold is intense enough to form ice: much snow falls on the mountains, and often a little in the plains. From March to May the winds blows with great violence, and bring heat with them. From May to September, the sky is serene, and the heat moderated by fresh breezes, which rise every evening and remain till morning. In autumn they have violent winds, like those of the spring; nevertheless, although these winds are very violent they scarcely ever produce tempests or hurricanes; but in summer there often arises along the Persian Gulph a very dangerous wind, called by the natives Samuel; it is still hotter and more terrible than that of Egypt. This wind is mortal, and acting like an inflamed vapour, it suffocates every person unfortunately enveloped within its vortex. In summer there also rises a wind of the same kind along the Red Sea, which suffocates men and cattle, and which conveys so great a quantity of sand that many persons conceive this sea will in time be choaked up with what falls therein. There are often clouds of sand in Arabia which darken the air and form dangerous whirlwinds. At Veru Cruz, when the hot north winds blow, the houses of the town are almost buried under the sand. In summer hot winds rise also at Negapatam, in the peninsula of India, likewise at Petapouli and Masulapatan. These burning winds, which destroy people, are fortunately of short duration, but they are very violent, and the greater swiftness they come with the more dreadful are their heats, whereas all other winds refresh so much the more as their velocity is greater. This difference proceeds from the degree of heat in the air, for while the heat of the air is not so great as that of the body of animals, the motion of the air is refreshing; but if the heat of the air exceeds that of the body, then its motion heats and burns. At Goa the winter, or rather the rainy and tempestuous season, is May, June, and July, and without which rains the heat would be perfectly unsupportable in that country.

The Cape of Good Hope is famous for its tempests, and the singular cloud which produces them. This cloud appears at first like a small round spot in the sky, called by the sailors the Ox's Eye. Probably its appearing so minute is owing to its exceeding great height.

Of all travellers who have spoken of this cloud, Kolbe appears to have the most examined it with attention; his words are, "The cloud seen on the mountains of the Table, or of the Devil, or of the Wind, is composed, if I am not deceived, of an infinity of small particles, impelled first against the mountains of the Cape towards the east, by the easterly wind which blows during almost the whole year in the torrid zone; these particles are stopt in their course by these high mountains, and collect on their eastern side; they then become visible and form these assemblages of clouds, which being incessantly driven by the east wind, rise to the summit of these mountains; they do not long remain there at rest, but being obliged to advance, they ingulph themselves between the hills before them, where they are bound and confined as in a canal; the wind presses them from above, and the opposite sides of the two mountains retain them in a direct line: in advancing they arrive at the foot of a mountain, where the country is a little more open, they then expand, and become again invisible; but they are shortly driven against other mountains, by clouds which are behind them, and thus proceed with much impetuosity, until they arrive at the highest mountains of the Cape, which are those of the Wind, or Table, where they have to encounter a wind blowing in an exact contrary direction; this occasions a dreadful conflict, for the vapours being impelled behind and repelled before, produce horrible whirlwinds either on the high mountains of the Table, or adjacent vallies. When the north-west wind yields, the south-east increases and continues to blow with more or less violence for six months, it reinforces itself while the cloud of the Ox's Eye is thick, because the vapours collected behind press forward, and it diminishes as soon as its thickness is lessened, because there are fewer particles and less pressure, and it is entirely lowered when the Ox's Eye is no longer apparent, because no new or not sufficient vapours any longer come from the east.

"All the circumstances attending this phenomenon lead to an hypothesis, which well explains every part of them: First, behind the mountain of the Table we remark a train of light white mists, which commencing on the eastern descent of this mountain, incline to the sea, and occupy the mountains of Stone throughout all their extent; I have often contemplated this train, which according to my opinion was caused by the rapid passage of the vapour above-mentioned, from the mountains of Stone to that of the Table.

"Secondly, These vapours must be extremely embarrassed in their road, by the frequent shocks and counter shocks caused, not only by the mountains, but also by the south and east winds which reign at places circumjacent to the Cape: I have already spoken of the two mountains called Hanging Lip and Norvege, situate on the points of False Bay; when the particles which I conceive are impelled on these mountains by the easterly winds, they are repelled from them by the south, which carry them on the neighbouring mountains; they are stopt there and appear like clouds, which is often the case upon the mountains of False Bay. These clouds are frequently very thick above the land which the Dutch are in possession of, on the mountains of Stenltenborch, of Drakenstein, and Stone, but particularly on the mountains of the Table, and of the Devil.

"In short, what confirms me in my opinion is, that constantly two or three days before the south-east wind blows on the Lion's Head, small black clouds are perceived above it; these clouds, according to my opinion, are composed of the particles or vapours which I have spoken of. If the north-west wind prevails when they arrive there, they are stopped in their course, but are never driven to a great distance till the south-east winds commence."

The first mariners who approached the Cape of Good Hope were ignorant of the effects of these clouds, which appear to form in the air so slowly, and without any motion, but which in a moment excite the most dreadful storms that precipitate the largest vessels to the bottom of the sea. In the country of Natal, a small cloud similar to the Ox's Eye at the Cape, produces the like effects. In the sea between Africa and America, especially near the equator, these kind of tempests very often arise. Near the coast of Guinea, three or four of these storms sometimes happen in a day; they are also caused and announced by small black clouds; the rest of the sky being generally serene, and the sea perfectly calm. The first blast which issues from these clouds is furious, and would sink ships in open sea, if they did not take the precaution to furl the sails. It is principally in April, May, and June these tempests are experienced on the coast of Guinea, because no regular wind blows there. The stormy season on the coasts of Loango is in January, February, March, and April. On the other side of Africa, at Cape of Gardafu, these kinds of tempests rise in May, and the clouds which produce them are generally in the north like those of the Cape of Good Hope.

All these tempests are produced by winds which issue from a cloud, and which have directions either from north to south, or north-east to south-west, &c. but there are other kinds which are still more violent, and in which the winds seem to proceed from every quarter at once; they have a whirling motion, which nothing can resist. A calm generally precedes these horrible tempests; but in an instant the fury of the winds raises the waves as high as the clouds. There are parts of the sea which cannot be approached, from there being constantly calms and hurricanes in them. The Spaniards have called these places Calms and Tornados; the most considerable are near Guinea, at two or three degrees north latitude; they are 300 or 350 leagues in length by as many in breadth, which forms a space of more than 100,000 leagues square.

When contrary winds come all at once in the same place, as to a centre, they produce whirlwinds by the contrariety of their motions; but when these winds meet with others in opposition, which counterbalance their action, they then revolve in a considerable circle, and occasion a dead calm, through which it is impossible for vessels to make their way. These places of the sea are marked in Senex's globes. I am inclined to think that the contrariety of the winds alone could not produce this effect if the direction of the coasts, and the particular form of the bottom of the sea, did not contribute thereto. I imagine that the currents caused by the winds, but directed by the form of the coasts and the inequalities of the bottom of the sea, end at these places, and that their opposite and contrary direction, in a plain surrounded on all sides by a chain of mountains, is the real cause of these tornados.

Whirlpools appear to be no other than the eddies of the water formed by the action of two or more opposite currents. The Euripus, so famous for the death of Aristotle, alternately absorbs and rejects the water seven times in twenty-four hours. This whirlpool is near the Grecian coast. The Charybdis, which is near the straits of Sicily, rejects and absorbs the water thrice in twenty-four hours. We are not quite certain as to the number of alternative motions in these whirlpools. Doctor Placentia, in his treatise, says, that the Euripus has irregular motions for eighteen or nineteen days every month, and regular ones for the other eleven; that in general it swells about one foot, and seldom two: he says likewise that authors do not agree as to the tides of the Euripus; that some assert it is twice, some seven, others fourteen times in twenty-four hours, but that Loirius having examined it attentively, observed it rose regularly every six hours, and with so violent a motion, that it was sufficient to turn the wheel of a mill.

The greatest known whirlpool is that in the Norway sea, which is affirmed to be upwards of twenty leagues in circumference. It absorbs for six hours water, whales, ships, and every thing that comes near it, and afterwards returns them in the same quantity of time as it drew them in.

It is not necessary to suppose there are holes and abysses in the bottom of the sea which swallow up the waters continually; to assign a reason for whirlpools, it is well known that when water has two contrary directions, the combination of these motions produce a whirling, and seem to form a void place in the centre. It is the same with respect to whirlpools in the sea, they are produced by two or three contrary currents; and as the flux and reflux, which run every six hours in contrary directions, are the principal cause of currents, it is not astonishing that whirlpools, which result from them, attract and swallow up all that surrounds them, and afterwards reject all they have absorbed in the same portion of time.

Whirlpools, therefore, are produced by opposite currents, and likewise by the meeting of contrary winds. These whirlwinds are common in the sea of China and Japan, near the Antilles, and in many other parts of the sea, particularly near projecting lands and high coasts; but they are still more frequent upon land, and their effects are sometimes prodigious. "I have seen," says Bellarmin, "an enormous ditch dug up by the wind, and the earth thereof carried to a distance; so that the place from whence it had been taken appeared a frightful hole, and the village upon which it was dropped was entirely buried with it."

In the history of the French Academy, and in the Philosophical Transactions, are the detail of the effects of many hurricanes, which appear inconceivable and scarcely credible, if the facts were not attested by a great number of intelligent testimonies.

It is the same with respect to water-spouts, which mariners never see without fear and amazement; these are very frequent near certain coasts of the Mediterranean, especially when the sky is cloudy and the wind blows at the same time from various coasts. They are more common near the coasts of Laodicea, Grecgo and Carmel, than in other parts of the Mediterranean. Most of them are large cylinders of water which fall from the clouds, although it appears, when we are at some distance, that the water of the sea rises up to the clouds.[G]

But there are two kinds of water-spouts, the first of which, alluded to above, is no other than a thick compressed cloud, reduced to a small space by contrary winds, which, blowing at the same time from many corners, give it a cylindric form, and causes the water to fall by its own weight. The quantity of water is so great, and the fall so sudden and precipitate, that if unfortunately one of these spouts breaks on a vessel, it shatters it to pieces and sinks it in an instant. It is asserted, and possibly with foundation, that these spouts may be broken and destroyed by the commotion which the firing of cannons excites in the air; which answers to the effect of dispersing thunder-clouds by the ringing of bells.

The other kind of water-spout is called a typhon, which many authors have confounded with the hurricane, in speaking of the storms of the Chinese sea, which is in fact subject to both. The typhon does not descend from the clouds, but rises up from the sea with great violence. By whirlwinds, sands, earth, houses, trees, and animals, are raised in the air, and transported to different parts; but typhons, on the contrary, remain in the same place, and can only have subterraneous fires for their origin; for the sea is then in the greatest agitation, and the air so strongly filled with sulphurous exhalations, that the sky appears covered with a copper-coloured crust, although there are no clouds, and the sun or stars may be seen through the vapour. It is to these subterraneous fires the warmth of the sea of China in winter must be attributed, as these typhons are there very frequent.[H]

Thevenot, in his voyage to the Levant, says, "we saw water-spouts in the Persian gulph, between the islands Quesomo, Lareca, and Ormutz. I think few people have considered water-spouts with so much attention as I have done. I shall mention my remarks with all possible simplicity, in order to render them plain and easy to be comprehended.

"The first that we saw appeared on the northern coast, between us and the island Quesomo, about a gun-shot from the ship: we directly perceived the water boiled on the surface of the sea, and was raised about a foot: it was whitish, and the top appeared like a thick black smoke, so that it properly resembled some burning straw, which only smoked. It made a noise like a torrent that runs with rapidity into a deep valley. This noise was mixed with another, similar to the hissing of serpents: a little afterwards we perceived something like a dark pipe, which resembled smoke ascending towards the clouds, turning round with great velocity: this appeared about the thickness of my finger, and the same noise still continued. After this it disappeared, having remained somewhat less than a quarter of an hour. This over, we perceived another on the south side, which began in the same manner as the preceding: directly after a third made its appearance on the west, and then a fourth by its side. The farthest of them was not more than a musket-shot from us. They all appeared like burning heaps of straw, a foot and a half or two feet high, and were attended with the same noise as the first. We afterwards saw three pipes or canals descending from the clouds to the water. They were broad at the top and lessened downwards, something in the shape of a trumpet, or as the paps of an animal, drawn perpendicularly down by a heavy weight. These canals appeared of a darkish white, occasioned, as I think, by the waters which were in them; for apparently they were formed before the water entered, as when they were empty they were no longer to be seen, like as a clear glass tube placed at some distance before our eyes, is not perceptible if it is not filled with some coloured liquor. These pipes were not strait but crooked in some places; they were not even perpendicular, but from the clouds, where they were joined, to the parts which drew in the water, they were very much bent; and what is more particular, the cloud, to which the second of the three was fastened, having been driven by the wind, this pipe followed it without breaking or quitting the place where it drew in the water, and passing behind the first, they had for some time the form of St. Andrew's cross. At the beginning neither of them was more than an inch in thickness, excepting just at the top, but afterwards the first of the three increased considerably. The two others scarcely remained longer than that which we saw on the north side. The second, on the south side, remained about a quarter of an hour, but the first on that side remained longer, and gave us some apprehensions. At first it was not bigger than my finger, afterwards it swelled as thick as my arm, then as my leg, and at last as the trunk of a large tree, which a man might encompass with both his arms. We distinctly perceived water through this transparent body, which ascended in a serpentine manner. Sometimes it diminished in size at the top, and sometimes at the bottom, then it exactly resembled a tube with some fluid matter pressed with the fingers, either above to make this liquor descend, or at bottom to cause it to ascend; and I am persuaded that it was the violence of the wind which caused these changes, pressing the pipe in a similar manner. After this it diminished less than my arm, then returned as large as my thigh, and then again became very small; at last I saw the water that was raised from the surface began to lower, and the end of the pipe divided from it, when, by the change of light from a cloud, it was lost to our sight; I continued, however, to observe whether it returned, because I had remarked that the pipe of the second had appeared to be broken in the middle, and directly after we saw it whole. This we found was occasioned by the light which hid the half from us, but the last we saw no more.

"These water-spouts are very dangerous, for if they fall on a vessel they entangle in the sails so much that sometimes they raise it up, and afterwards let it fall with such violence as to sink it; at least if they do not lift the vessel up, they tear all the sails, or let the water they contain fall on it, and which often sinks it to the bottom. There cannot be the least doubt but it is by similar accidents that many ships, of which we have heard no accounts, have been lost, since there are but few examples of those that we have known, from certainty, to have perished in this manner."

I suspect there are many optical illusions in the above account, but I have recounted them as related, in order that we might compare them with those of other travellers. The following description is by M. Gentil, in his voyage round the world. "At eleven o'clock in the morning, the air being filled with clouds, we perceived about our vessel, at a quarter of a mile distant, six water-spouts, which made a noise similar to that of water flowing in subterraneous canals, and increased until it resembled the whistling which an impetuous wind makes among the cordage of a ship. We at first observed the water to boil up about a foot and a half above the surface. Above this boiling there appeared a mixed or rather a thick smoke, which formed a kind of canal, that ascended to the clouds. These canals inclined according as the wind moved the clouds to which they were attached, and in spite of the wind's impulsion they not only adhered to them, but even lengthened and shortened themselves in proportion as the clouds rose higher or lower in the atmosphere.

"These phenomena terrified us greatly, and our sailors, instead of being bolder, fomented their fears by the dismal tales they told each other. If these spouts, said they, fall on our vessel, they will lift her up, and then she will sink by the violence of her fall. Others contended in a decisive tone, that they would not raise the vessel up, but if they met it in their course, being full of water, the ship would break the communication they had with the sea, and the whole body of the water would fall perpendicularly on the deck of the vessel and split her to pieces.

"To prevent this misfortune the cannon was loaded, the sailors pretending the report of a cannon, by agitating the air, dissipated these phenomena; but we had no need of having recourse to this remedy, for when they had run about ten minutes about the ship, some at a quarter of a league, others at a less distance, we perceived the canals to grow narrower by degrees, till they got loose from the surface of the sea and then dissipated."

It appears from the description given by these two travellers, that water-spouts are produced, at least in part, by the action of a fire or smoke which rises from the bottom of the sea with great force, and that they are quite different from those produced by contrary winds.

"The water-spouts, says Mr. Shaw, which I had an opportunity of seeing, appeared as so many cylinders of water, which fell from the clouds, although by the reflection of the columns which descend, or by the drops which detach themselves from the water they contain, it sometimes seems, especially when we are at some distance, that the water is drawn up from the sea. To render a reason for this phenomena we may suppose that the clouds being collected in one part by opposite winds, they force them by pressing them with violence to condense and descend in this manner."

There still remain many facts to be acquired before we can give a complete explanation of these phenomena; it appears to me, that if there are under the waters of the sea, at particular places, soils mixed with sulphur, bitumen, and minerals, these matters may be inflamed and produce a great quantity of air, which being newly generated and prodigiously rarefied, ascends with rapidity, and may raise these water-spouts from the sea to the sky; so likewise if, by inflammation, the sulphurous matters which a cloud contains, a current of air is formed, which descends perpendicularly from the clouds towards the sea, all its water may follow the current of air, and form a water-spout which will fall from the sky upon the sea; but it must be allowed that the explanation of this kind of water-spout, no more than that we have given of those produced by contrary winds, is not satisfactory; and it might be asked why these kinds of water-spouts, which fall perpendicularly from the clouds, are not as often seen on the land as on the sea?

The History of the Academy, anno 1727, mentions a land water-spout which appeared at Capestan, near Beziers; it descended from a cloud like a black pillar, which diminished by degrees, and at length terminated in a point upon the surface of the earth. It obeyed the wind which blew from west to south-west. It was accompanied with a very thick smoke, and made a similar noise to that of a troubled sea. It tore up and carried away trees to the distance of forty or fifty feet, marking its way by a large track, on which three carriages might have passed each other. There appeared another pillar of the same kind, but which soon joined the first; and after the whole had disappeared, a great quantity of hail fell on the earth.

This kind of water-spout appears to be still different from the other two: it is not mentioned to have contained water; and it seems, by what I have related, and by the explanation given thereof by M. Andoque, to the academy, that this water-spout was only a whirlwind, rendered visible by the dust and condensed vapours which it contained.

In the same history, anno 1741, a water-spout is spoken of, seen on the lake of Geneva; the upper part was inclined to a very black cloud, and the lower, which was narrower, terminated a little above the water. This phenomenon remained only a few minutes, and, at the moment it was dissipated, a thick vapour was perceived at the part where it first appeared; the waters of the lake boiled and seemed to make an effort to rise up. The air was very calm during the whole time; and when it disappeared neither wind nor rain ensued. "After all we are acquainted with," says the historian of the academy, "concerning water-spouts, is not this another proof that they are not formed by the conflict of the winds, but almost always produced by volcanos or subterraneous vapours, from which we know the bottom of the sea is not exempt? Whirlwinds and hurricanes, which we commonly thought to be the cause of these appearances, may possibly be only the effect, or an accidental event thereof."

ARTICLE XVI.

OF VOLCANOS AND EARTHQUAKES.

The burning mountains, called volcanos, contain in their bowels, sulphur, bitumen, and other matters of an inflammable nature, the effects of which are more violent than that of gunpowder, or even thunder, and have from the earliest ages terrified mankind, and desolated the country. A volcano is an immense cannon, whose orifice is often more than half a league: from this wide mouth are vomited forth torrents of smoke and flames, rivers of bitumen, sulphur, and melted metals, clouds of cinders and stones, and sometimes it ejects enormous rocks to many leagues distance, which human powers united could not move; the conflagration is so terrible, and the quantity of burnt, melted, calcined, and vitrified matters which the mountain throws out, is so great, that they destroy cities and forests, cover fields an hundred and two hundred feet in thickness, and sometimes form hills and mountains, which are only heaps of these matters piled up together. The action of this fire, and the force of its explosion, is so violent, that it produces by its re-action, succussions which shake the earth, agitate the sea, overthrow mountains, and destroy the most solid towers and edifices, even to very considerable distances.

These effects, although natural, have been looked upon as prodigies; and although we see in miniature, by fire, effects nearly similar to those of volcanos, yet there is something in grandeur, of whatever nature it may be, that invariably strikes the imagination and influences the mind, and therefore I am not surprised that some authors have taken them for the vents of a central fire, and ignorant people for the mouths of Hell. Astonishment produces fear, and fear is the mother of superstition. The natives of Iceland imagine the roarings of the volcano are the cries of the damned, and its eruptions the effects of the rage of devils, and the despair of the wretched.

All its effects, however, arise from fire and smoke: veins of sulphur, bitumen, and other inflammable matters, are found in the bowels of mountains, as well as minerals and pyrites, which ferment when exposed to air or humidity, and cause explosions proportionate to the quantity of inflamed matters. This is the just idea of a volcano, and it is easy for a philosopher to imitate the action of these subterranean fires; for by mixing together a quantity of brimstone and iron filings, and burying them in the earth to a certain depth, a small volcano may be produced, whose effects will be exactly similar; for this mixture inflames by fermentation, throws off the earth and stones with which it is covered, and smokes, flames, and explodes like a real volcano.

In Europe are three famous volcanos, Mount Ætna, in Sicily, Mount Hecla, in Iceland, and Mount Vesuvius, near Naples, in Italy. Mount Ætna has burnt from time immemorial, its eruptions are very violent, and the quantity of matter it throws out is so great that after digging 68 feet deep, marble pavements, and the vestiges of an ancient town have been found buried under this thickness of matter, in the same manner as the city of Herculaneum has been covered by the matter thrown out from Vesuvius. New mouths in Ætna were opened in 1650, 1669, and at other times. We see the flame and smoke of this volcano from Malta, about 60 leagues distance; it smokes continually, and there are times when it vomits flames, stones, and matters of every kind with impetuosity. In 1537, there was an eruption of this volcano, which caused an earthquake in Sicily that continued for 12 days, and which overthrew a number of houses and public structures; it ceased by the opening of a new mouth, the lava from which burnt every thing within five leagues of the mountain. The cinders thrown out by the volcano were so abundant, and ejected with so much force, that they were driven as far as Italy; and vessels at some distance from Sicily were incommoded by them. Farelli says the foot of this mountain is 100 leagues in circumference.

This volcano has now two principal mouths, one narrower than the other; smoke comes continually from them, but flames never issue but during the time of eruptions; it is pretended that large stones have been thrown out by them to the distance of 60,000 feet.

In 1683 a violent eruption caused a terrible earthquake in Sicily; it entirely destroyed the town of Catanea, and killed more than 60,000 persons in that town, besides those which were destroyed in the neighbouring towns and villages.

Hecla throws out its fires through the ice and snow of a frozen land; its eruptions are nevertheless as violent as those of Ætna, and other volcanos of southern countries. It throws out cinders, lava, pumice stones, and sometimes boiling water: it is not inhabitable within six leagues of this volcano, and the whole island of Iceland is very abundant in sulphur. The history of the violent eruptions of Hecla are recorded by Dithmar Bleffken.

Mount Vesuvius, according to the historians, did not begin burning till the seventh Consulate of Titus Vespasian and Falvius Domitian; the top being opened, it at first threw out stones and rocks, afterwards fire and lava, which burnt two neighbouring towns, and emitted such thick smoke that it obscured the light of the sun. Pliny the elder, desirous of examining this conflagration nearer, was suffocated by the smoke.[I]

Dion Cassius relates, that this eruption was so violent, that cinders and sulphurous smoke were driven as far as Rome, and even beyond the Mediterranean into Africa. Heraclea was one of the two towns burned by this first conflagration of Vesuvius, which, in these latter times has been discovered at more than 60 feet deep, the surface above which was become, by length of time, arable land and fit for culture. The relation of the discovery of Heraclea is in the hands of the public, and we can only wish that some person, versed in Natural History, would examine the different matters which compose this soil of 60 feet, attending to their disposition and situation, the alterations they have produced or suffered, the direction they have taken, and the hardness they have acquired.

There is an appearance that Naples is situate on a hollow ground, filled with burning materials, for Vesuvius and Solfatera seem to have interior communications. When Vesuvius casts out lava Solfatera emits flames, and when the one ceases the other is extinguished. The city of Naples is situate nearly between them.

One of the last and most violent eruptions of Mount Vesuvius was in the year 1737.[J] The mountain vomited, by several mouths, large torrents of burning metallic matters, which dispersed themselves over the country, and flowed into the sea. Mons. Montealegre, who communicated this relation to the Academy of Sciences, observed, with horror, one of these rivers of fire, whose length, from the mountain to the sea, was about seven miles, its breadth about 60 feet, its depth 25 or 30 palms, and in bottoms or vallies 120: the matter which flowed was like the scum which issues from the furnace of a forge, &c.[K]

In Asia, particularly in the islands of the Indian ocean, there are many volcanos; one of the most famous is Mount Albours, near Mount Taurus, eight leagues from Herat; its summit continually smokes, and it frequently throws out flames and burning matter in such quantities that the surrounding country is covered with cinders. In the island of Ternate there is a volcano which throws out matter like pumice-stones. Some travellers assert that this volcano is most furious at the time of the equinoxes, because certain winds then reign there, which inflame the matter that feeds, and has fed this fire for a number of years.[L]

The island of Ternate is but seven leagues round, and is only the summit of a mountain; it gradually ascends from the shore to the middle of the island, where the volcano rises to a considerable height, to the top of which it is very difficult to attain. Many rills of sweet water descend along the ridge of this mountain, and when the air is calm, and the season mild, this burning gulph is in less agitation than during storms and high winds.[M] This confirms what I have said in a former article, and seems to prove that the fire of volcanos does not proceed from any considerable depth, but from the top, or at least not far distant from the summit of the mountain; for if it was not so, the high winds could not increase their combustion. There are other volcanos in the Malaccas. In one of the Mauritius islands, 70 leagues from the Malaccas, there is a volcano, whose effects are as violent as those of Mount Ternate. Sorca island, one of the Malaccas, was formerly inhabited. In the middle of this island there is a lofty mountain, with a volcano at the top. In 1693 this volcano vomited bitumen and inflamed matters in such a great quantity as to form a burning lake, and which covered the whole island.[N]

At Japan, and in the adjacent islands, there are several volcanos, which emit flames during the night and smoke in the day. At the Philippine islands there are also burning mountains. One of the most famous volcanos of the islands in the Indian ocean, and the most recent, is that near the town of Panarucan, in the island of Java; it opened in 1586, and at the first eruption, it threw out an enormous quantity of sulphur, bitumen, and stones. The same year Mount Gounapi, in the island of Banda, which continued only seventeen years, opened and ejected, with a frightful noise, rocks and matters of every kind. There are also some other volcanos in India, as at Sumatra, and in the north of Asia, but those are not considerable.

In Africa, there is a mountain, or rather a cavern, called Beniguazeval, near Fez, which always emits smoke, and sometimes flames. One of the islands of Cape de Verd, called the Fuogo, is only a large mountain which burns continually; this volcano throws out cinders and stones; and the Portuguese, who have attempted several times to erect habitations in this island, have been constrained to abandon the project through dread of the volcano. The Peak of Teneriffe, considered as one of the highest mountains of the earth, throws out fire, cinders, and large stones; from its top rivulets of melted sulphur flow across the snow, where it forms veins that are distinguishable at a great distance.

In America there are a great number of volcanos, particularly in the mountains of Peru and Mexico; that of Arequipa is one of the most famous; it often causes earthquakes, which are more common in Peru than in any other country in the world. The volcano of Carrappa and that of Malahallo are, according to the report of travellers, the most considerable, next to that of Arequipa; but there are many others in these parts of which we have no exact knowledge. M. Bouguer, in his voyage to Peru, published in the Memoirs of the Academy of the year 1744, mentions two volcanos, called Cotopaxi and Pichincha; the first at some distance from, the other near the town of Quito; he was witness of a conflagration of Botopaxi in 1742, and of the orifice which was made in that mountain; this eruption did no other damage than melting the snow and producing such torrents of water, that in less than three hours inundated a tract of country 18 leagues in extent, and overthrew all they met with in their way.

At Mexico the most considerable volcanos are Popochampeche, and the Popoatepec; it was near this last that Cortes passed in his voyage to Mexico; some of the Spaniards ascended to the top, where they saw the mouth, which was about half a league in circumference. Sulphurous mountains are also met with at Guadaloupe, Tercera, and other islands of the Azores; and, if we were to consider as volcanos all those mountains which smoke, or emit flames, we might reckon more than sixty; we have only spoken of those formidable volcanos, near which no person dares to inhabit.

These volcanos which are in such great numbers in the Cordeliers, as I have formerly said, cause almost continual earthquakes, which prevent the natives from building with stone above one story high, and to construct the upper stories of their houses with reeds and light wood. In these mountains are also many precipices and large vents, the sides of which are black and burnt, as in the precipice of Mount Ararat, in Armenia, which is called the Abyss; these abysses are the mouths of extinguished volcanos.

There was lately an earthquake at Lima, the effects of which were dreadful. The town of Lima and Port Callao were almost entirely swallowed up; but the evil was still greater at Callao. The sea rose and covered every building in that town, drowned all the inhabitants, and left only one single tower remaining. Of twenty-five ships that were in this port, four were carried a league upon land, and the rest were swallowed up by the sea. At Lima, which was a large town, there remains only twenty-seven houses standing; a great number of persons were buried in the ruins, particularly monks and religious persons, as their buildings were higher and constructed of more solid materials than the other houses. This misfortune happened at night, in October 1746; the shock remained fifteen minutes.

There was formerly near the port of Pisca, in Peru, a famous city, situate on the sea shore, which was almost entirely destroyed by an earthquake that happened the 19th of October 1682, for the sea having extended beyond its common bounds, swallowed up this unfortunate place with every person that was in it.

If we consult historians and travellers, we shall find relations of many earthquakes and eruptions of volcanos, whose effects have been as terrible as those we have just mentioned. Pesidonius, whom Strabo quotes in his first book, relates, that a city in Phœnicia, near Sidon, was swallowed up by an earthquake, with the neighbouring territory, and even two thirds of Sidon; this effect was not so sudden but that many of the inhabitants had time to avoid it by flight. This shock extended throughout all Syria, and as far as the Cyclade islands, and into Eubœa, where the fountains of Arethusa suddenly stopped, and did not reappear for many days after, and then by many new springs remote from the old ones; that this earthquake did not cease from shaking the island, sometimes in one part and sometimes in another, until the earth opened in the valley of Lepanta, and ejected a great quantity of lava and other inflamed matters. Pliny, in his first book, chap. 84, relates, that in the reign of Tiberius an earthquake happened which overthrew twelve towns in Asia: and in his second book he mentions a prodigy caused by an earthquake. St. Augustin records, that by a great earthquake there were towns overthrown in Lybia. In the time of Trajan, the town of Antioch, and a great part of the adjacent country were swallowed up by an earthquake; and in the time of Justinian, in 528, it was a second time destroyed by the same cause, with upwards of 40,000 of its inhabitants. Sixty years after, in the time of St. Gregory, it felt the effects of a third earthquake, when 60,000 of its inhabitants perished. In the time of Saladin, in 1182, most of the towns of Syria and Judea were destroyed by the same calamity. In Calabria and Apulia, there have been more earthquakes than in any other part of Europe. In the time of Pope Pius II. all the churches and palaces of Naples were overthrown, and above 30,000 of its inhabitants killed; the remainder were obliged to live in tents till houses were built. In 1629, there were earthquakes in Apulia, which destroyed 7000 persons, and in 1638, the town of St. Euphemia was swallowed up, and there remains only a stinking lake in its place. Ragusa and Smyrna, at the same time, were also almost destroyed. There was an earthquake in 1692, which extended into England, Holland, Flanders, Germany, and France; it was chiefly felt on the sea coasts and near large rivers; it shook at least 2600 square leagues; it lasted only two minutes, and the motion was more considerable on mountains than in vallies.[O] On the 10th of July, 1688, there was an earthquake at Smyrna, which began by a motion from west to east; the castle was at first overthrown, its four walls being divided and sunk six feet in the sea; this castle stood upon an isthmus, but is at present a real island, about 100 paces distant from the land. The walls from east to west are fallen down, those from north to south are yet standing; the city, which is ten miles from the castle, was destroyed shortly after; in many places the earth opened, and subterraneous noises were heard; five or six shocks were felt as night came on, the last continued only half a minute; the ships in the roads were shaken; the ground of the town was lowered about two feet; not above a quarter of the town withstood the shock, and those principally the houses which stood on rocks; from 15 to 20,000 persons are computed to have been buried under the ruins.[P] In 1695, an earthquake was felt at Bologna, in Italy, and it was remarked as a particular circumstance, that the water was much troubled a day before.[Q][R]

At Tercera there happened an earthquake on the 4th of May, 1614, which overthrew in the town of Angra eleven churches and nine chapels, besides private houses; and in the town of Praya it was so terrible, that scarcely an house was left standing. On the 16th of June 1628, there was an earthquake in the island of St. Michael, the effects of which was so great, that in a place where the sea was more than 150 fathoms deep an island was thrown up more than a league and a half long, and upwards of 60 fathoms high. Another happened in 1691, in the island of St. Michael, which began the 6th of July, and lasted till the 12th of the following month: Tercera and Fayal were agitated the next morning with so much violence, that they appeared to move; but these frightful shocks returned there only four times, whereas at St. Michael they did not cease a moment for several days. The islanders quitted their houses, which they saw fall before their eyes, and remained all the time in the fields exposed to the injuries of the weather. The whole town of Villa Franca was overthrown to its very foundation, and most of the inhabitants buried under its ruins. In many parts the plains rose into hills, and in others, mountains were flattened into vallies. A spring of water issued from the earth, which flowed for four days, and then ceased all on a sudden. The air and sea, still more agitated, resounded with a noise which might have been taken for the roaring of a number of wild animals. Many persons died with the fright; the ships in the harbour suffered dangerous shocks, and those which were at anchor, or under sail at 20 leagues distant from the islands, received great damage. Earthquakes are frequent in the Azores, and about twenty years before a mountain in St. Michael was overturned by one of them.[S]

In Manilla, in the month of September, 1627, an earthquake levelled one of the two mountains called Carvallos, in the province of Cagayon; in 1645, one third of the town was destroyed by a like accident, and 300 persons perished. The succeeding year it experienced another; and the ancient Indians say they were more terrible formerly, which was the reason they build their houses only of wood; a custom still continued, and which the Spaniards follow.[T]

"The quantity of volcanos in this island confirms that assertion; because at certain times they vomit forth flames, shake the earth, and perform all the effects Pliny attributes to those of Vesuvius; that is, they change the beds of rivers, drive back the adjacent sea, fill with cinders the neighbouring plains, and throw out stones to great distances, with reports louder than those of cannons.

"In 1646, a mountain in the island of Machian split by an earthquake, with a dreadful noise; from this opening issued a number of flames, which destroyed several plantations with the inhabitants and all that was therein. In the year 1685, this prodigious crack was to be seen, and probably is still apparent; it is called the path of Machian, because it descends from the top to the bottom, like a road hollowed out, but which at a distance appears like a path."[U]

The history of the French Academy mentions in the following terms, the earthquakes that took place in 1702 and 1703. "The earthquakes began in Italy in October 1702, and continued, till July 1703; the country which suffered the most by them, and where they began, is the town of Norcia, with its dependencies under the ecclesiastical government, and the province of Abruzzo, which are situated at the foot of the Apennines on the south side.

"They were often accompanied with terrible noises in the air, which also were heard without any dreadful effects, when the sky was serene. The earthquake which happened on the 2d of February 1703, was the most violent; it was accompanied, at least at Rome, with a great serenity of sky and calmness in the air. It lasted at Rome half a minute, and at Aquila the capital of Abruzzo three hours. It destroyed the whole town of Aquila, buried 5000 persons under the ruins, and made great havock in the environs. The vibration of the earth, according to the observations made by the lamps in the churches, was from south to north.

"It opened two places from whence issued a great quantity of stones, which entirely covered it and rendered it barren; after the stones they threw out water above the height of the trees; this lasted half an hour, and inundated the adjacent fields. The water was whitish, like soap suds, and had not any remarkable taste.

"A mountain near Sigillo, a city twenty-two miles distant from Aquila, had on its summit a very large plain surrounded with rocks like a wall. The earthquake of the 2d of February, changed this plain into a gulph of unequal breadth, whose greatest diameter is twenty-five fathoms and the least twenty; the depth of it has not been discovered, although a line 300 fathoms has been let down in it. At the time this opening was made, flames were seen to issue out, and afterwards a great smoke which lasted three days with some interruptions.

"At Genoa on the 1st and 2d of July 1703, there were two slight earthquakes, the last was felt only by the people on the pier: at the same time the sea in the port sunk six feet, and remained so a quarter of an hour.

"The sulphurous water in the road from Rome to Tivoli it diminished two feet and a half, both in the bason and in the canal. In many places of the plain, called Testine, the springs and rivulets, which formed morasses, are all dried up. The waters of the lake called l'Enfer is also lowered three feet. In place of the ancient springs new ones have appeared at above a league distance, so that possibly they are the same waters which have changed direction[V].

"The same earthquake which, in 1538, formed Monti di Cinere, near Pozzoli, filled lake Lucrin with stones, earth and cinders, so that this lake is now a marshy ground.[W]

"There are earthquakes also felt at some distance at sea, says Mr. Shaw; in 1774, being on board the Gazella, an Algerine vessel, mounting 50 guns, three violent shocks were felt one after the other, as if every time a weight of 20 or 30 tons had been thrown on the ballast. This happened on a part of the Mediterranean that was more than 200 fathom deep. He relates also, that others had felt earthquakes much more considerable in other parts, and one among the rest at 40 leagues west from Lisbon."[X]

Schouten, speaking of an earthquake in the Malacca islands, says, that the mountains were shaken, and the vessels at anchor in 30 or 40 fathoms water were shook, as if they had struck against rocks or banks. "Experience, continues he, teaches us every day that the same happens in the open sea, where no bottom is to be met with, and that ships are tossed to and fro by earthquakes, even where the sea is tranquil."

Gentil, in his voyage round the world, speaks of earthquakes in the following terms: "I have, says he, made some remarks on these earthquakes; first, that half an hour before the earth is agitated every animal is struck with fear; horses snort, break their fastenings, and fly from the stable; dogs bark; birds, as if stupified, fly into houses for safety; and rats and mice quit their holes. Secondly, that vessels at anchor are so violently agitated, that every part of them seems as if going to pieces, the cannons force themselves loose, and the masts break in several places. These facts I should scarcely have given credit to if many unanimous testimonies had not convinced me. I know the bottom of the sea is a continuation of the land, and that if one is agitated it will communicate to the other; but I could not conceive how every part of a vessel, floating in a fluid, should be affected in the same manner as if she was on the earth: it appeared to me that her motion should have been such as she experiences in a storm; besides, in the circumstance which I speak of, the surface of the sea was smooth, and there was no wind. Thirdly, that if the cavern of the earth, where this subterraneous fire is contained, has a direction from north to south, and if the buildings of an adjacent town are in a parallel line with it, all the houses are overthrown, whereas if this vein or cavern executes its effects by the breadth of the town, the devastation of the earthquake, is much less considerable."[Y]

In countries subject to earthquakes, when a new volcano breaks out earthquakes cease, and are only felt in the violent eruptions of the volcano, as is observed in the island of St. Christopher.[Z]

The enormous ravages produced by earthquakes have made some naturalists think that mountains and other inequalities of the surface of the globe were only the effects of subterraneous fires, and that all the irregularities must be attributed to the violent shocks which they have produced. This, for example, is the opinion of Mr. Ray; he imagines that all mountains have been formed by earthquakes, or the explosion of volcanos, as Monti di Cinere, the new island near Santorini, &c. but he has not considered that the slight elevations formed by the eruption of a volcano, or by the action of an earthquake, are not internally composed of horizontal strata, as all other mountains are; for by digging in the Monti di Cinere we meet with calcined stones, cinders, burnt earths, metallic dross, pumice-stones, &c. all mixed and confounded like a heap. Besides, if earthquakes and subterraneous fires had produced the great mountains of the earth, as the Cordeliers, Mount Taurus, the Alps, &c. the prodigious force necessary to raise these enormous masses might, at the same time, have destroyed a great part of the surface of the globe; and earthquakes, requisite to produce such effects, must have been of inconceivable violence, since the most famous of which history makes mention have not had sufficient power to form a single mountain; for example, in the time of Valentian I. an earthquake happened, which was felt throughout all the known world;[AA] and yet not a mountain was thrown up by it.