194 THE PHYSICAL GEOGRAPHY OF THE SEA. 



design, the beautiful and exquisite adjustments that we see here 

 provided, to insure the perfect workings of the great aqueous and 

 atmospherical machine. This coincidence — may I not call it 

 cause and effect ? — is between the hygrometrical conditions of all 

 the countries within, and the hygrometrical conditions of all the 

 countries without, the range included within the lines which I have 

 drawn (Plate VII.) to represent the route in the northern hemi- 

 sphere of the southeast trade-winds after they have blown their 

 course over the land in South Africa and America. Both to the 

 right and left of this range are countries included between the same 

 parallels in which it is, yet these countries all receive more water 

 from the atmosphere than they give back to it again ; they all have 

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

 the Rhine, 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 rivers of China ; and in North America, in the latitude 

 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 magnificent. 



403. It is remarkable that none of these copiously-supplied wa- 

 ter-sheds have, to the southwest of them in the trade-wdnd 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 coun- 

 tries in the extra-tropical north which I have described as lying 

 under the lee of trade-wind South America and Africa are scanti- 

 ly supplied with rains. Pray examine Plate VII. in this connec- 

 tion. It tends to confirm the views taken in Chapter V., p. 115. 



404. 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 Europe ; and yet the waters dis- 

 charged by the St. Lawrence give us an idea of how greatly the 

 precipitation upon it is in excess of the evaporation. To wind- 

 ward 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 



