298 THE PHYSICAL GEOGRAPHY OF THE SEA. 



rivers running into the sea. On the one hand, there is in Europe 

 the Khine, the Elbe, and all the great rivers that empty into the 

 Atlantic ; on the other hand, there are in Asia the Ganges, and 

 all the great Chinese rivers ; and in North America, in the lati- 

 tude of the Caspian Sea, is our great system of fresh-water lakes ; 

 all of these receive from the atmosphere immense volumes of wa- 

 ter, and pour it back into the sea in streams the most majestic. It 

 is remarkable that none of these copiously-supplied water-sheds 

 have, to the southwest of them in the trade-wind regions of the 

 southern hemisphere, any considerable body of land ; they are, all 

 of them, under the lee of evaporating surfaces, of ocean waters in 

 the trade-wind regions of the south. Only those countries in the 

 extra-tropical north which I have described as lying under the 

 lee of trade-wind South America and Africa are scantily supplied 

 with rains. Pray examine Plate YII. in this connection. It tends 

 to confirm the views taken in Chapter YII. The surface of the 

 Caspian Sea is about equal to that of our lakes ; in it, evaporation 

 is just equal to the precipitation. Our lakes are between the same 

 parallels, and about the same distance from the western coast of 

 America that the Caspian Sea is from the western coast of Eu- 

 rope ; and yet the waters discharged by the St. Lawrence give us 

 an idea of how greatly the precipitation upon it is in excess of the 

 evaporation. To windward of the lakes, and in the trade-wind 

 regions of the southern hemisphere, is no land ; but to windward 

 of the Caspian Sea, and in the trade-wind region of the southern 

 hemisphere, there is land. Therefore, supposing the course of the 

 vapor-distributing winds to be such as I maintain it to be, ought 

 they not to carry more water from the ocean to the American 

 lakes than it is possible for them to carry from the land — from the 

 interior of South Africa and America — to the valley of the Cas- 

 pian Sea? In like manner (§ 865), extra-tropical New Holland 

 and South Africa have each land — not water — to the windward of 

 them in the trade-wind regions of the northern hemisphere, where, 

 according to this hypothesis, the vapor for their rains ought to be 

 taken up : they are both countries of little rain ; but extra-trop- 

 ical South America has, in the trade-wind region to windward of 

 it in the northern hemisphere, a great extent of ocean, and the 

 amount of precipitation (§ 299) in extra-tropical South America 

 is wonderful. The coincidence, therefore, is remarkable, that the 



