188 INFLUENCE OF THE FOREST ON PRECIPITATION. 
of air which come from other regions are cooled as they ap¬ 
proach the wood by its less heated atmosphere, and obliged to 
let fall 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 accumu¬ 
lated and condensed to rain. The forest thus has a 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 precipitation. * * * 
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 their treeless neighborhood, which, 
in consequence of the ready mobility of the air and its constant 
changes, receive a share of the characteristics of the forest 
atmosphere, coolness and moisture. * * * When the dis¬ 
tricts stripped of trees have long been deprived of rain and 
dew, * * * and the grass and the 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.” * 
Asbjornsen, after adducing the familiar theoretical argu¬ 
ments on this point, adds: “ The rainless territory in Peru 
and North Africa establish this conclusion, and numerous 
other examples show that woods exert an influence in pro¬ 
ducing rain, and that rain fails where they are wanting; for 
many countries have, by the destruction of the forests, been 
deprived of rain, moisture, springs, and watercourses, which 
are necessary for vegetable growth. * * * The narratives 
of travellers show the deplorable consequences of felling 
the woods in the Island of Trinidad, Martinique, San Do- 
* Om Slovene og deres Forhold til Nationalceconomien , pp. 131 - 133 . 
