THE TREES OF AMERICA. 25 



"Inhuman man! curse on thy barbarous art, 

 And blasted be thy murder-aiming eye j 

 May never pity soothe thee with a sigh, 

 Nor ever pleasure glad thy cruel heart ! " 



Trees and shrubs, then, are important as giving homes and shelter for the birds. 

 We have said that they probably affect the climate, and of course agriculture, 

 more by preventing the rapid abstraction of caloric and evaporation of moisture 

 by the wind, than in any other manner. If, for instance, a thermometer be 

 placed in the open air, even when it is but slightly in motion, the mercury will 

 cool down much more rapidly than when it is placed under the shelter of trees. 

 We have tried the experiment repeatedly, and in various ways, during the past 

 winter, (1855-6,) and have found, for example, that if the instrument were 

 taken from the house at 65°, and placed in a current of air 2° below zero, it 

 would fall to that point in three minutes, although the air was not moving very 

 rapidly ; while, if placed under the shelter of a thin growth of trees, it would be 

 ten minutes reaching the same point. It wUl be readily understood from this why 

 we feel colder and freeze more quickly when the wind blows, than when it is stUl, 

 though the thermometer may indicate a much lower degree of temperature under 

 the latter condition ; it is because the wind takes away the heat from the system 

 faster than it can supply it ; and the same effect is produced upon living, growing 

 plants, — which supply their own vital heat. Blight is caused in many cases 

 and the growth of plants is retarded, — fruit is prevented from maturing, and 

 ripening, — the new wood, even, fails to be matured, and during the next winter 

 it is "winterkilled," and many valuable trees are thus lost. From this it 

 appears how necessary it is that every species of vegetation should have shelter 

 from the violence of the wind during certain stages of growth ; and we are 

 able to appreciate the benefit of Mr. Tudor's wise experiments, since forest 

 trees must constitute in most cases, as nature has intended they should, the 

 barriers against the forces of the wind god. By further following out this 

 subject, I think we shall see how blight, and other diseases may come from the 

 same source. This word is used to express several different kinds of disease ; 

 but in its most extended sense, as far as I am able to ascertain, it may in 



