THE ATMOSPHERE. 93 



templating the physical arrangements of the earth from such points 

 of view as this is which we now have before us ; from it the sea, 

 and the air, and the land, appear each as a part of that grand 

 machinery upon which the well-being of all the inhabitants of 

 earth, sea, and air depends ; and which, in the beautiful adapta- 

 tions that we are pointing 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 con- 

 structed and arranged according to one human design. 



149. 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 may be considered as the excess of 

 the precipitation over the evaporation that takes place in the val- 

 ley drained by that river. 



150. This excess comes from the sea; the winds convey it to 

 the interior ; and the forces of gravity, dashing it along in mount- 

 ain torrents or gentle streams, hurry it back to the sea again. 



151. In other parts of the earth the evaporation and precipita- 

 tion are exactly equal, as in those inland basins such as that in 

 which the city of Mexico, Lake Titicaca, the Caspian Sea, &c., 

 &;c., are situated, which basins have no ocean drainage. 



152. If more rain fell in the v-alley 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. 



153. In the sheets of w^ater 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. 



154. Adaptations. — In contemplating 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 



