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A HISTORY OF 



uniform and even; in such a place, the wind 

 arising from a simple cause, must have but 

 one simple motion. In fact, we find it so. 

 There are many parts of the world where 

 the winds, that with us are so uncertain, pay 

 their stated visits. In some places they are 

 found to hlow one way by day, and another 

 by night ; in others, for one half of the year, 

 they go in a direction contrary to their former 

 course: but, what is more extraordinary still, 

 there are some places where the winds never 

 change, but for ever blow the same way. 

 This is particularly found to obtain between 

 the tropics in the Atlantic and ^Ethiopic 

 oceans ; as well as in the great Pacific sea. 



Few things can appear more extraordinary 

 to a person who has never been out of our 

 variable latitudes, than this steady wind, that 

 for ever sits in the sail, sending the vessel 

 forward ; and as effectually preventing its re- 

 turn. He who has been taught to consider 

 that nothing in the world is so variable as the 

 winds, must certainly be surprised to find a 

 place where there is nothing more uniform. 

 With us their inconstancy has become a pro- 

 verb ; with the natives of those distant cli- 

 mates they may talk of a friend or a mistress 

 as fixed arid unchangeable as the winds, and 

 mean a compliment by the comparison. When 

 our ships are once arrived into the proper 

 latitudes of the great Pacific ocean, the ma- 

 riner forgets the helm, and his skill becomes 

 almost useless : neither storms nor tempests 

 are known to deform the glassy bosom of 

 that immense sheet of waters; a gentle breeze, 

 that for ever blows in the same direction, 

 rests upon the canvass, and speeds the na- 

 vigator. In the space of six weeks, ships are 

 thus known to cross an immense ocean, that 

 takes more than so many months to return. 

 Upon returning, the trade-wind, which has 

 been propitious, is then avoided : the mari- 

 ner is generally obliged to steer into the nor- 

 thern latitudes, and to take the advantage 

 of every casual wind that offers, to assist him 

 into port. This wind, which blows with such 

 constancy one way, is known to prevail riot 

 only in the Pacific ocean, but also in the 

 Atlantic, between the coasts of Guinea and 

 Brazil ; and, likewise, in the vEthiopic ocean. 

 This seems to be the great universal wind, 

 blowing from the east to the west, that pre- 



vails in all the extensive oceans, where the 

 land does not frequently break the general 

 current. Were the whole surface of the 

 globe an ocean, there would probably be but 

 this one wind, for ever blowing from the east, 

 and pursuing the motions of the sun west- 

 ward. All the other winds seem subordinate 

 to this ; and m.vny of them are made from the 

 deviations of its current. To form, therefore, 

 any conception relative to the variations of 

 the wind in general, it is proper to begin with 

 that which never varies. 



There have been many theories to explain 

 this invariable motion of the winds ; among 

 the rest, we cannot omit that of Dr. Lyster, 

 for its strangeness. " The sea," says he, " in 

 those latitudes, is generally covered over with 

 green weeds, for a great extent ; and the air 

 produced from the vegetable perspiration of 

 these, produces the trade-wind." The theory 

 ofCartesius was not quite so absurd. He al- 

 leged, that the earth went round faster than 

 its atmosphere at the equator ; so that its mo- 

 tion, from west to east, gave the atmosphere 

 an imaginary one from east to west ; and thus 

 an east wind was eternally seen to prevail. 

 Rejecting those arbitrary opinions, conceived 

 without force, and asserted without proof, Dr. 

 Halley has given one more plausible; which 

 seems to be the reigning system of the day. 



To conceive his opinion clearly, let us for 

 a moment suppose the whole surface of the 

 earth to be an ocean, and the air encompas- 

 sing it on every side, without motion. Now 

 it is evident, that that part of the air which 

 lies directly under the beams of the sun, will 

 be rarefied ; and if the sun remained for ever 

 in the same place, there would be a great 

 vacuity in the air, if I may so express it, be- 

 neath the place where the sun stood. The 

 sun moving forward from east to west, this va- 

 cuity will follow too, and still be made under 

 it. But while it goes on to make new vacui- 

 ties, the air will rush in to fill up those the sun 

 has already made ; in other words, as it is still 

 travelling forward, the air will continually be 

 rushing in behind, and pursue its motions from 

 east to west. In this manner the air is put 

 into motion by day; and by night the parts 

 continue to impel each other, till the next re- 

 turn of the sun, that gives a new force to the 

 circulation. 



