THE FOREST AS A FLOOD-PREVENTER 59 
As to the influence which the forest exerts on the 
precipitation of moisture, there is considerable doubt. 
The extent of this influence is still merely a matter 
of opinion, and is, in short, a case of ‘ not proven.” 
It is safe to assume, however, that the forest mechan- 
ically increases the precipitation of moisture on high 
mountains and, to a less extent, in some lowlands. 
Where the forests are bathed by clouds and mists, 
large quantities of water are collected from the satu- 
rated atmosphere by the twigs, leaves, and limbs of 
trees and bushes. In many moist districts there is a 
constant drip of water from the branches, although it 
may not be actually raining. The larger the surface 
exposed, the more moisture is accumulated. The 
leafage, herbage, trunks, and branches of the forest 
offer a large surface on which it may accumulate. A 
forest on a high mountain, projecting into the clouds, 
draws from them large quantities of moisture, just as 
the wick of a lamp soaks up oil. The forest may have 
some influence on local showers, but in the case of 
general rainfall, its influence is so uncertain that it 
need not be rated in the consideration of floods. The 
forest is rather the result of rainfall, than rainfall the 
result of the forest. 
The most violent floods are due to sudden heavy 
downpours of rain in regions with circular-shaped and 
steep-sided collecting-basins. In regions where the 
