§ 549. THE GEOLOGICAL AGENCY OF THE WINDS. 297 



(§ 260) that the volume of water returned by the rivers, the rains, 

 and the dews, into the whole ocean, is exactly equal to the volume 

 which the whole ocean gives back to the atmosphere ; as far as our 

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

 manent 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 vapor 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 be- 

 ginning to lay down more moisture than they take up again. In 

 the Obi, the Yenesi, and the Lena is to be found the volume 

 which contains the expression for the load of water which these 

 winds have brought from the southern hemisphere, from the 

 Mediterranean, and the Eed Sea ; for in these almost hyperborean 

 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 them than they have taken 

 up again and carried off. The low temperatures of Siberian Asia 

 are quite sufScient to extract from these winds the remnants of 

 vapor which the cool mountain-tops and mighty rivers of the 

 southern hemisphere have left in them. 



549. Here I may be permitted to pause, that I may call atten- 

 How climates in one tiou to auothcr remarkable coincidence, and admire 

 S'^\Tarmn?e^ thc marks of design, the beautiful and exquisite ad- 



upon tne arrange 

 uient of land in th( 

 other, and upon the 



uient of land in the jugtments that wc hcrc see provided, to insure the 



course of the winds, pgpfect workiugs of thc great aqueous and atmos- 

 pherical machine. This coincidence — may I not call it cause and 

 effect? — is between the hygrom^trical conditions of all the coun- 

 tries within, and the hygrometrical conditions of all the countries 

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

 (Plate YII.) to represent the route in the northern hemisphere 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 paral- 

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

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



