THE GEOLOGICAL AGENCY OF THE WINDS. 297 



knowledge extends, the level of each of these two seas is as. 

 permanent as that of the great ocean itself. Therefore, the 

 volume of water discharged by rivers, the rains, and the dews,, 

 into these two seas, is exactly equal to the volume which these 

 two seas give back as vapour to the atmosphere. These winds,, 

 therefore, do not begin permanently to lay down their load of 

 moisture, be it great or small, until they cross the Oural 

 Mountains. On the steppes of Issam, after they have supplied 

 the Amazon and the other great equatorial rivers of the south, 

 we find them first beginning to lay down more moisture than 

 they take up again. In the Obi, the Yenesi, and the Lena is ta 

 be found the volume that indicates the load of water which these 

 winds have brought from the southern hemisphere, from the 

 Mediterranean, and the lied Sea; for in these almost hyper- 

 borean river- basins do we find the first instance in which,, 

 throughout the entire range assigned these winds, they have^ 

 after supplying the Amazon, etc., left more water behind theui 

 than they have taken up again and carried oft*. The low 

 temperatures of Siberian Asia are quite sufficient to extract from 

 these winds the remnants of vapour which the cool mountain-tops, 

 and mighty rivers of the southern hemisphere have left in them- 

 549. How climates in one hemisphere depend upon the arrangemeni 

 of land in the other, and upon the course of the ivinds. — Here I may 

 be permitted to pause,^ that I may call attention to another 

 remarkable coincidence, and admire the marks of design, the 

 beautiful and exquisite adjustments that we here see provided, 

 to insure the perfect workings of the great aqueous and atmo- 

 spherical 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 witliout, the range included within the lines which I 

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

 hemisphere of the south-east 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 Ehine, 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 iiv 



