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clines a little. But whatever is the direction at any one place, it continues the same throughout the whole year without any variation, and always blows from some southerly point. But there is this difference between the wind on the coasts of Chili and Angola, that it extends much farther out to sea upon the for mer than upon the latter.
In order to explain the cause of this singular phenomenon, it is necessary to recollect, that the general trade-wind is produced by the concurrence of two separate causes. One is the great heat of the equatorial region, by which alone would be produced a constant north or south wind. The other is the diurnal revolution of the earth, which would cause a perpetual tendency of the air in these warm regions from east to west. From the concurrence of these two causes result the general trade-winds, which would. constantly blow from S. E. or N. E. as we have already demonstrated. But if, in any particular place, one of these two powers be prevented from acting, while the other continues to exert its influence, the general direction of the wind will be varied. Thus, if the east wind was checked, while nothing interrupted the south or north wind, the air would rush towards the equator in that direction which was nearest and easiest, whether that fhould be pointing eastward or westward. Now, as the high mountains in the internal parts of Africa and America interrupt the course of the east wind, near the surface of the earth, while those coasts, of which we now treat, are entirely open to the south, the wind naturally rushes along the coasts of Chili and Angola from south to north; and as the low
lands, near the fhore, in these warm regions, are generally warmer than the sea, the wind will naturally point in towards the 'fhore, as is generally observed there to take place.
This then is evidently the cause of the south wind which always prevails upon the coasts of Chili and Peru, as well as along the fhores of Angola, Loango, in Africa, c. But it is only near the fhore that this can take place; nor can it extend a great way above these low and fertile regions. For as the internal parts of these countries are exceedingly high, but more especially the Andes of America, which experience a perpetual degree of cold, more intense than some polar regions ever are subjected to, the air must here be condensed to a very great degree, and send forth from these high regions a perpetual wind to every side, which occasions almost all the peculiarities that have been remarked in these climates; for, by opposing the general current of the tradewind upon the eastern parts of these continents, they produce those deluges of rain which feed the immense rivers of the Amazons, la Plata, &c. These rivers do not, like the Nile and Gambia, swell only at a particular season, and then fhrink into a diminutive size again; but continue throughout the whole year, with a lefs variation of size, to pour their immense floods into the ocean. These cold winds, likewise, stretching to the westward, at a considerable distance above the warmest regions of the sea coast, at length descend as low as the ocean, and form the general trade-wind, and occasion that unusual degree of cold which mariners have so often complained of, even under the line, to the westward of America.
To the same cause also must we attribute the thick fogs so common upon the southern parts of Chili, and along, the coasts of Peru, with the other peculiarities of that singular climate about Lima, and the kingdom of Valles, in South America; for the vapours which are exhaled in such great abundance in the warm regions on the sea fhore, are, at a little height above the earth, condensed by the cold winds which come from the mountains, and form these thick mists which are so often observed in this climate.
The same effects are felt in some degree on the similar coasts of Africa. But as the mountains of Africa are not so high as the Andes of America, nor approach so near the western coast, the effects are lefs sensible here than in America. The great height of the Andes, above the mountains of the similarly situated country of Africa, is the only reason why the effects on that coast are not felt to an equal degree, although similar in kind.
Winds in the bay of Panama and on the Guinea coast.
A more singular deviation of the trade-wind is ob-served to take place on the African and American coasts to the north of the line, than those we have taken notice of to the south of it. For it is observed, that from California to the bay of Panama, all along the coast of New Spain, the winds blow almost constantly from the W. or S. W. nearly directly opposite to the trade-wind; and on the coast of Africa from Cape Bayador to Cape Verde, they blow chiefly from the N. W. standing in upon the fhore; from thence the wind bends gradually more and more from the north to the west, and so round to S. W.
all along the coast of Guinea, as will be distinctly seen by the map.
After what we have said of the winds on the Southern parts of these regions, it will be unnecefsary to spend much time in explaining the causes of these peculiarities, as it will evidently appear that they are nearly the same; the variation here observed being occasioned by the particular direction of the coast. Thus, along the coast of New Spain, the wind blows nearly in the same direction in every place, as there are no remarkable bendings on that coast; being uniformly drawn towards the shore, by the great heat of the continent near the sea, which in these regions is always more heated than the water of the ocean, and occasions that inflection. But, as the coast of Africa is more irregular, the winds are also found to be more different in their direction. To the north of Cape Verde, as the coast stretches nearly south and north, the wind being drawn towards it a little, blows from the N. W. But beyond that the coast bends more eastward to Cape Palmas; from which it runs E. or N. E. all along the coast of Guinea, the wind fhifting gradually more and more to the west, still pointing in upon the coast. And as there is nothing to oppose the current of air, which comes from the south along the coast of Angola, it stretches forward till it comes within the influence of the coast of Guinea, and is there drawn in towards the shore in a S. W. direction, but as it is only the lower regions of the coast of Guinea which are so much warmed, the high mountains within continuing cold, the northerly wind coming from these, meeting
and opposing the southerly winds in the higher regions of the air, by their mutual conflicts occasion those incefsant rains and tremenduous thunder-storms so remarkable along the whole of this uncomfortable coast.
It has been observed by mariners, that there is a tract of sea, to the west of Guinea, from five to ten degrees of north latitude, in which the trade-wind blows with lefs steadiness than in any other part of that ocean, being almost constantly troubled with calms and tornadoes. The cause of this the reader will perceive by inspecting the map, as he will easily see that the winds are drawn from this quarter, almost in every direction, so that there can be here no ́ constant wind; but being exhausted of its air, it must become lighter than the circumjacent parts, and must then be supplied from either side as chance or occasional circumstances may direct, which occasions those sudden flurries and tornadoes here observed. To be continued.
REFLECTIONS OF FREDERICK THE GREAT.
Continued from p. 248.
"No, my dear Anaxagoras, my philosophic zeal does not vent itself against you, who are a true sage, but against those blockheads, who, assuming the specious title of philosophers, take upon themselves to make worlds according to their whimsical hypotheses.
I had taken it for granted, from the progrefs of good sense, that science would at last have undeceived those who scrutinise nature; but I see I have been mistaken. Such world-makers I consign to the hospital for learned lunatics." Letter CCXX.
To be continued.