132 OUTLINES OF FORESTRY. 



Generally, the air of the forest is cooler and 

 damper in summer than the air over the open 

 fields in the same district. 



1st. Because the air of the forest is shielded 

 from the direct rays of the sun. 



2d. Because the air is chilled by evaporation from 

 the moister ground. 



A large tract of forest in any section of country 

 tends to prevent marked changes in its climate, as 

 compared with those that occur in the same region 

 over the open fields. 



1. By permitting the wooded area to more thor- 

 oughly absorb the sun's heat on account of the 

 greater surface it presents. 



2. By keeping the air moister and, therefore, 

 better able to absorb the sun's heat. 



3. By acting as a screen to the land to the lee- 

 ward of a cold wind. 



4. By preventing the frost from penetrating the 

 ground to too great a depth before protected by a 

 covering of snow. 



Geikie, in his " Text-Book of Geology," * in 



* Reprinted, by permission, from " Text-Book of Geology," 

 by Archibald Geikie, LL.D., F.R.S. London : Macmillan & 

 Co., 1882. Pp.971. 



