§ Co."». EASTING OF THE TRADE- WINDS, ETC. 1(J3 



between the Mississippi and the Rocky Mountains, owing to the 

 singular effect of those mountains upon the cHmate, is larger than 

 the space they comprehend between the Mississippi and the At- 

 lantic. Hyetographically it is also different, being dryer, and pos- 

 sessing a purer atmosphere. In this grand range of climate be- 

 tween the meridians of 100° and 110° W., the amount of precipi- 

 tation is just about one half of what it is between those two iso- 

 therms east of the Mississippi. In this new country west of it, 

 winter is the dry, and spring the rainy season. It includes the 

 climates of the Caspian Sea, which Humboldt regards as the most 

 salubrious in the world, and where he found the most delicious 

 fruits that he saw during his travels. Such was the purity of the 

 air there, that polished steel would not tarnish even by night ex- 

 posure. These two isotherms, with the remarkable loop which 

 they make to the northwest, beyond the Mississippi, embrace the 

 most choice climates for the olive, the vine, and the poppy ; for 

 the melon, the peach, and almond. The finest of wool may be 

 grown there ; and the potato, with hemp, tobacco, maize, and all the 

 cereals, may be cultivated there in great perfection. No climate 

 of the temperate zone w^ill be found to surpass in salubrity that 

 of this Piedmont trans-Mississippi country. The calm zone of 

 Capricorn is the duplicate of that of Cancer, and the winds flow 

 from it as they do from that, both north and south, but with this 

 difference : that on the polar side of the Capricorn belt they pre- 

 vail from the northwest instead of the southwest, and on the equa- 

 torial side from the southeast instead of the northeast. Now if it 

 be true that the vapor of the northeast trade-winds is condensed 

 in the extra-tropical regions of the southern hemisphere, the fol- 

 lowing path, on account of the effect of diurnal rotation of the 

 earth upon the course of the winds, would represent the mean cir- 

 cuit of a portion of the atmosphere moving according to the gen- 

 eral system of its circulation over the Pacific Ocean, viz. : coming 

 down from the north as an upper current, and appearing on the 

 surface of the earth in about longitude 120° west, and near the 

 tropic of Cancer, it would here commence to blow the northeast 

 trade-winds of that region. To make this clear, see Plate VII., on 

 which I have marked the course of such vapor-bearing winds ; A 

 being a breadth or swath of winds in the northeast trades ; B, the 

 same wind as the upper and counter - current to the southeast 



