CH. IV. 



MISCELLANEOUS. 



133 



within reach of atmospheric aeration. This doubles 

 the extent of space available for the roots ; it gives 

 two sides of a square instead of one ; and compared 

 with the side of the hill if unterraced, space is gained 

 instead of lost ; it gives two sides of a square instead 

 of a diagonal. 



We are not to expect that trees drawn up in the Effect of 



wind on 



interior of sheltered plantations and transplanted to 

 exposed situations will grow. If we could move a 

 cube acre of ground, with a young tree, from a sheltered 

 to an exposed situation, the plant would dwindle and 

 decay. A tree grown in an exposed situation contrives 

 by degrees to shelter itself ; that is, it grows to leeward 

 of itself. For the windward growth diverts the current 

 of the wind, and throws it up. And we see, in ex- 

 posed trees and woods, that they get taller by degrees 

 from the windward to the leeward side. The chief 

 injury which trees suffer from wind is while they are 

 shooting. If the weather is calm while they are shoot- 

 ing, they will make a year's growth upward and to 

 windward. But their general growth will be only 

 upward and to leeward ; not from being bent by the 

 wind that way, but from all other growth being de- 

 stroyed while the shoots are tender, and from the wind 

 having a much greater power to break twigs which 

 meet it than those which grow down the wind.* 



* Wind does not increase cold to plants as it does to animals. 

 Plants have no heat. Animals have a heat of 92°, and wind of 

 a temperature under 92° deprives animals of the heat which 

 would haug about their coats, or about the clothes of us poor 



