PLANTS PROTECTED BY SNOW/ 183 



\->her, to enable you to understand me. Some 

 bodies retain heat longer than others, and snow 

 is one of these bodies : different substances are 

 said to be good or bad conducters of heat, in 

 proportion to their capacity of keeping or losing 

 it. Air is a body, marble is a body, and water 

 is a body; but when marble and water are 

 surrounded by air, you find the air is warm, in 

 comparison with water and marble. 



Now, if these bodies retained heat in the 

 same degree as the air which surrounds them, 

 their temperature would be the same ; yet you 

 find the water and marble colder than the air; 

 that is, the marble and the w^ater part w r ith 

 some of the heat to the air, which therefore has 

 more of it, and is consequently warmer: now r , 

 snow does not part with heat quickly ; that is, 

 it does not become cold quickly, which is the 

 same thing ; and when it has formed a covering 



