CULTIVATION. lb', 



robs the vapor in the atmosphere of its heat, and 

 causes it to be deposited on its own surface. It 1> 

 as though the pitcher were sweating, but the water 

 all comes from the atmosphere, not, of course, through 

 the sides of the pitcher. 



If we breathe on a knife-blade, it condenses in the 

 same manner the moisture of the breath, and 

 covered with a film of water. 



Stone houses are damp in summer, because the 

 inner surfaces of the walls, being cooler than the 

 atmosphere, cause its moisture to be deposited in tin- 

 manner described. By leaving a space, h<\\. 

 between the walls and the plaster, this inoi-tu: 

 prevented from being troublesome, and if the space 

 is closed against the circulation of air containing 

 moisture there will be no vapor brought in contact 

 with the cool surface of the wall, and therefore no 

 deposit of moisture. 



Nearly every night in the summer season, the cold 

 earth receives moisture from the atmosphere in the 

 form of dew. 



A cabbage, which at night is very cold, condenses 

 water to the amount of a gill or more. 



The same operation takes place in the soil. When 

 the air is allowed to circulate among its lower and 

 cooler particles, they receive moisture from the ta mi- 

 process of condensation. Therefore, when, by the 

 aid of under-drains, the lower soil becomes sufiicient- 

 ly open to admit of a circulation of air, the deposit .f 

 atmospheric moisture will keep the soil supplied with 

 water at a point easily accessible to the roots of plants. 



