130 PHYSICAL GEOGRAPIIY OP TILE SEA, AND ITS METEOROLOGY. 



air depeuds ; and which, in the beantiful adaptations that we 

 are endeavouring; to point out, affords new and striking evidence 

 that they all have their origin in one omniscient idea, just 

 as the different parts of a watch may be considered to have been 

 constructed and arranged according to one human design. In 

 some parts of the earth the precipitation is greater than the 

 evaporation : thus the amount of water borne down by every 

 river that runs into the sea (§ 270) may be considered as the 

 excess of the precipitation over the evaporation that takes place 

 in the valley drained by that river. In other parts of the earth 

 the evaporation and precipitation are exactly equal, as in those 

 inland basins such as that in which the city of Mexico, Lake 

 Titicaca, the Caspian Sea, etc., etc., are situated, which basins 

 have no ocean drainage. If more rain fell in the valley of the 

 Caspian Sea than is evaporated from it, that sea would finally 

 get full and overflow the whole of that great basin. If less fell 

 than is evaporated from it again, then that sea, in the course of 

 time, would dry up, and plants and animals there would all 

 perish for the want of water. In the sheets of water which we 

 find distributed over that and every other inhabitable inland 

 basin, we see reservoirs or evaporating surfaces just sufficient 

 for the supply of that degree of moisture which is best adapted 

 to the well-being of the plants and animals that people such 

 basins. In other parts of the earth still, we find places, as the 

 Desert of Sahara, in which neither evaporation nor precipitation 

 takes place, and in which we find neither plant nor animal to fit 

 the land for man's use. 



303. Adaptations — their beauties and sublimity. — In contem- 

 plating the system of terrestrial adaptations, these researches 

 teach one to regard the mountain ranges and the great 

 deserts of the earth as the astronomer does the counterpoises 

 to his telescope — though they be mere dead weights, they 

 are, nevertheless, necessary to make the balance complete, the 

 adjustment of his machine perfect. These counterpoises give 

 ease to the motions, stability to the performance, and accuracy 

 to the workings of the instrument. They are " comjoensations.^* 

 Whenever I turn to contemplate the works of nature, I am 

 struck with the admirable system of compensation, with the 

 beauty and nicety with which eveiy department is adjusted, 

 adapted, and regulated according to the otheis ; things and 

 principles are meted out in directions apparently the most 



