3 



cross the ocean from east to west, on a calm and 

 pacific sea, which Spanish sailors call the Ladies 

 Gulf, el Golfo de las Damas. We found, as all 

 do who frequent those latitudes, that, in propor- 

 tion as we advance toward the west, the trade 

 winds, which were at first east-north-east, fix to 

 the east. 



Those winds, the most generally adopted theory 

 of which is explained in a celebrated treatise 

 of Halley*, are a phenomenon much more com- 

 plicated-^ than the greater number of naturalists 

 admit. In the Atlantic Ocean, the longitude as 

 well as the declination of the sun, influences the 

 direction and limits of the trade winds. On the 

 side of the New Continent, in both hemispheres, 



* The existence of an upper current of air, which blows 

 constantly from the equator to the poles, and of a lower cur- 

 rent, which blows from the poles to the equator, had already 

 been admitted, as Mr. Arago has shown, by Hooke. The 

 ideas of the celebrated English naturalist are developed in a 

 discourse on Earthquakes published in 1686. '* I think 

 (adds he,) that several phenomena, which are presented by 

 the atmosphere and the ocean, especially the winds, may be 

 explained by the polar currents." (Hooke's Posthumous 

 Works, p. 364.) This curious passage is not cited by Hal- 

 ley (Phil. Trans, vol. xxxix, p. 58). On the other hand, 

 Hooke, speaking directly of the trade winds (Post. Works, 

 p. 88 and 363), adopts the erroneous theory of Galileo, who 

 admits a difference of velocity between the movement of the 

 Earth and that of the air. 



t MSm. de 1' Acad. 1760. p. 18. D'Alembert, sur les 

 Causes g6n. des Vents, p. 5. 



