FOREST PLANTING. 105 



pumped up through their widely ramifying roots from considerable 

 depths in the ground. Thus a constant evaporation is produced 

 which keeps the forest atmosphere moist even in long droughts, when 

 all other sources of humidity in the forest itself are dried up. The 

 warm, moist currents of air which come from other regions are cooled 

 as they approach the wood by its less heated atmosphere, and obliged 

 to let fell the humidity with which they are charged. The woods 

 contribute to the same effect by mechanically impeding the motion of 

 fog and rain cloud, whose particles are thus accumulated and con- 

 densed to rain. The -forest thus has greater power than the open 

 ground to retain within its own limits already existing humidity, and 

 to preserve it, and it attracts and collects that which the wind brings 

 it from elsewhere, and forces it to deposit itself as rain or other pre- 

 cipitation. In consequence of these relations of the forest to humidity 

 it follows that wooded districts have both more frequent and more 

 abundant rain, and in general are more humid than woodless regions ; 

 for what is true of the woods themselves in this respect, is true also 

 of the open country in their neighborhood, which in consequence of 

 the ready mobility of the air and its constant changes, receives a share 

 of the characteristics of the forest atmosphere, coolness and moisture 

 When the districts stripped of trees have long been deprived of rain 

 and dew, and the grass and fruits of the field are ready to wither, the 

 grounds which are surrounded by woods are green and flourishing. 

 By night they are refreshed with dew, which is never wanting in the 

 moist air of the forest, and in due season they are watered by a 

 beneficent shower or a mist which rolls slowly over them." 



Asbjornson, after adducing the familiar theoretical 

 arguments on this point, adds : 



" The rainless territories in Peru and North Africa establish this 

 conclusion, and numerous other examples show that woods exert an 

 influence in producing rain, and that rain fails where they are want- 

 ing for many countries have, by the destruction of the forests, been 

 deprived of rain, moisture, springs and watercourses, which are 

 necessary for vegetable growth. In Palestine, and many other parts 



