230 THE PHYSICAL GEOGRAPHY OF THE SEA. 



or the upheaval of a range of mountains in certain parts of Amer- 

 ica, Africa, or Spain, across the route of the winds which brought 

 the rain for the Caspian water-shed, might have been sufficient to 

 rob them of the moisture which they were wont to carry away 

 and precipitate upon this great inland basin. See how the Andes 

 have made Atacama a desert, and of Western Peru a rainless 

 country ; these regions have been made rainless simply by the 

 rising up of a mountain range between them and the vapor-springs 

 in the ocean which feed with moisture the winds that blow over 

 those now rainless regions. 



642. That part of Asia, then, which is under the lee of south- 

 ern trade-wind Africa, lies to the north of the tropic of Cancer, 

 and between two lines, the one passing through Cape Palmas and 

 Medina, the other through Aden and Delhi. Being extended to 

 the equator, they will include that part of it which is crossed by 

 the continental southeast trade-winds of Africa, after they have 

 traversed the greatest extent of land surface (Plate VII.). 



643. The range which lies between the two lines that represent 

 the course of the American winds with their vapors, and the two 

 lines which represent the course of the African winds with their 

 vapors, is the range which is under the lee of winds that have, for 

 the most part, traversed water-surface, or the ocean, in their cu-- 

 cuit as southeast trade-winds. But a bare inspection of Plate VII. 

 will show that the southeast trade-winds which cross the equator 

 between longitude 15° and 50° west, and which are supposed to 

 blow over into this hemisphere between these two ranges, have 

 traversed land as well as water ; and the Trade- wind Chart* shows 

 that it is precisely those winds which, in the summer and fall, are 

 converted into southwest monsoons for supplying the whole ex- 

 tent of Guinea with rains to make rivers of. Those winds, there- 

 fore, it would seem, leave much of their moisture behind them, and 

 pass along to their channels in the grand system of circulation, for 

 the most part, as dry winds. Moreover, it is not to be supposed 

 that the channels through which the winds blow that cross the 

 equator at the several places named are as sharply defined in nature 

 as the lines suggested, or as Plate VII., would represent them to be. 



* Series of Maury's Wind and Current Charts. 



