16 THE ATMOSPHERE. 



The properties and operations of the atmosphere al- 

 ready mentioned, belong more to the several ingredients 

 which compose it, than to the whole substance as a mass. 

 It however possesses some properties, and performs many 

 great and important operations, in which it is to be 

 viewed as one body. For example, every particle of the 

 atmosphere, even in the dryest places and seasons, con- 

 tains a portion of moisture. By the power of absorbing 

 and retaining this substance, it performs a most extensive 

 and important service, in producing action, and pre- 

 serving order, health, and life, in moving and living 

 beings. It is constantly relieving the earth, and the 

 numerous bodies upon its surface, from their superfluous 

 moisture. It raises from the ocean, by the silent process 

 of evaporation, as much water as flows into it, by the 

 Amazon, the Mississippi, the Danube, the Ganges, the 

 Nile, and all other rivers which it receives into its bosom. 

 Experiments have proved that during twelve hours of a 

 summer's day, about twenty-five hogsheads are evaporated 

 from an acre, or sixteen thousand hogsheads from a square 

 mile. The water thus taken from the earth, and diffused 

 through the atmosphere, is again collected in clouds, and 

 when the air can no longer sustain their weight, they 

 fall in the form of rain, hail, or snow, and after enliven- 

 ing the face of nature, or passing into the ocean, the 

 same vehicle which before conducted it through this 

 round of services, again takes it up to repeat the process. 



Not only in relieving the earth from its superfluous 

 moisture, and in preparing materials for refreshing 

 showers, as well as the raging storm, but evaporation is a 

 most important and essential process for the chemist in 

 forming his salts and powders, for the farmer in preserv- 

 ing his hay, and for the mechanic and housekeeper in 

 their endless and nameless operations, for preparing the 

 comforts and the luxuries of civilized and refined society. 

 Besides going this round of ceremonies with water, in 

 taking it from the earth, in diffusing it far and wide, and 

 again collecting it in clouds, and returning it to refresh 

 the living creation, and to replenish rivers and the ocean ; 

 the atmosphere transports it, while in clouds or vapor, 

 from continent to continent, that it may give to the in- 



