ON THE GEOLOGICAL AGENCY OF THE WINDS. 191 



394. The range which hes between the two lines that represent 

 the course of the American winds with their vapors, and the tw^o 

 hnes w^hich 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 cir- 

 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 w^inds which, in the summer and fall, are 

 converted into southwest monsoons for supplying the whole extent 

 of Guinea with rains to make rivers of. Those winds, therefore, 

 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 equa- 

 tor at the several places named, are as sharply defined in nature 

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



395. The whole region of the extra-tropical Old World that is 

 included within the ranges marked, is the region which has most 

 land to w^indward of it in the southern hemisphere. Now it is a 

 curious coincidence, at least, that all the great extra-tropical des- 

 erts of the earth, with those regions in Europe and Asia which 

 have the least amount of precipitation upon them, should lie within 

 this range. That they are situated under the lee of the southern 

 continents, and have but little rain, may be a coincidence, I ad- 

 mit ; but that these deserts of the Old World are placed where 

 they are is no coincidence — no accident : they are placed where 

 they are, and as they are, by design ; and in being so placed, it was 

 intended that they should subserve some grand purpose in the ter- 

 restrial economy. Let us see, therefore, if we can discover any 

 other marks of that design — any of the purposes to be subserved 

 by such an arrangement — and trace any connection between that 

 arrangement and the supposition which I maintain as to the place 

 where the winds that blow over those regions derive their vapors, 



396. It will be remarked at once that all the inland seas of 

 Asia, and all those of Europe except the semi-fresh-water gulfs of 



* $eries of Maury's Wind and Current Charts. 



