CAUSE OF THE TRADE WINDS. 123 



sorte it is most certaine that the ayre mooves with the cir- LlB - m - 

 cular motion of the heaven, from Est to West, which is the 

 first ground before mentioned. The second is no lesse 

 certaine, the which is, that the motion of the aire in those 

 parts that are vnder the Line, or neere vnto it, is very swift 

 and light the more it approacheth to the Equinoctiall j but 

 the farther off it is from the Line, approaching neere the 

 Poles, the more slowe and heavie this motion is. The 

 reason heereof is manifest, for that the mooving of the celes- 

 tiall bodies being the efficient cause of the mooving of the 

 ayre, it must of necessitie be more quicke and light, where 

 the celestiall bodies have their swiftest motion. 



To labour to shew the reason why the heaven hath a 

 quicker motion vnder the burning Zone, which is the Line, * 

 then in any other part of the heaven, were to make small 

 account of men ; seeing it is easie to see in a wheele that 

 its motion is more slowe and heavy in the part of greatest 

 circumference then in the lesse, and that the greater cir 

 cumference ends at one instant with the lesser. From these 

 two grounds proceedes the reason where such as saile great 

 gulphs from east to west doe always finde the winde in 

 their poope, going in a small altitude, and the neerer they 

 come to the Equinoctiall, the more certaine and durable the 

 winde is. Arid contrariwise, sailing from west to east, they 

 always finde the winde contrary ; for that the swift motion 

 of the Equinoctiall drawes after it the element of the aire, 

 as it doth the surplus of the higher spheares. So as the 

 aire dooth alwayes follow the motion of the day, going 

 from east to weast, without any alteration and the motion 

 of the aire being swift, draweth after it all the vapours and 

 exhalations which rise from the sea, which causeth in those 

 Regions a continuall easterly winde, which runnes from the 

 Levant. Father Alonso Sanchez, a religious man of our 

 Company, who hath travelled the east and west Indies, 

 as a man ingenious and of experience, said, that sailing 



