[E]See Varen. Geography, gener. cap. 20.
[E]See Varen. Geography, gener. cap. 20.
There are regular winds produced by the melting of snows, which the ancient Greekshave 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].
[F]See Abridg. Phil. Tran. vol. II, page 129.
[F]See Abridg. Phil. Tran. vol. II, page 129.
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 commonlyattended 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 arriveat 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 strongerthan 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 cloudsthat 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 twolofty 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 overturnbuildings, 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 currentsof 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 fromAmerica 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 ofMay, 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-eastwind 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. Thenorth-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 tothe 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.
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 motionsof 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, along 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 Marchto 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, orof 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 vapoursbeing 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 theyarrive 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 whirlpoolsin 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 factswere 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]
[G]See Shaw's Travels, vol. 2. p. 56.
[G]See Shaw's Travels, vol. 2. p. 56.
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 brokenand 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]
[H]See Acta Eud. Lips. Supplementum, vol. 1. p. 405.
[H]See Acta Eud. Lips. Supplementum, vol. 1. p. 405.
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 breakingor 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, thenreturned 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 themas 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 willsink 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 somany 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 uponthe 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 explanationgiven 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 hasbeen 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]