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It appears to the writer that both theory, and the observation of the 
phenomena, substantiates the statement that deforestation greatly influ- 
ences the rainfall. 
It is not probable that the ordinary winter and spring precipitation is 
to any extent affected by the presence or absence of forest growth. That 
the summer and autumn rains are often greatly modified, on the other 
hand, can hardly be questioned. 
In the first place, the presence of a heavy leaf mulch, and of the very 
porous and highly-absorbent soil of a forested area, is a sufficient guaran- 
tee that at the beginning of the hot season the soil shall be filled with 
moisture from the winter and spring rains. Under the present deforested 
conditions of the hill lands the immediate run off is so great, because of 
their compact and rocky surfaces, that it is at least questionable whether 
the ground is ever fully saturated, even at the beginning of the summer 
season. Moreover, if such a compact soil were saturated, capillary action 
would cause a very rapid evaporation during the first few weeks of warm 
weather, and hence greatly diminish the supply of ground water before 
midsummer. 
Given, however, the soil and subsoil of a forested region thoroughly 
saturated with water at the opening of the hot season, the leaf and loose 
soil mulch effectively stops evaporation resulting from capillary action. 
The ground water then is largely conserved until drawn from the soil by 
means of the roots of the forest trees, and evaporated from the leaf sur- 
faces later in the season, when the trees need the moisture for growth. It 
is a well-known fact that the evaporation from the leaf surfaces of the 
greater number of trees in a moist climate is very important. Carefully 
conducted experiments have shown that from the leaves of a birch tree 
of moderate size, from 600 to 900 pounds of moisture is evaporated in 
twenty-four hours, and that from a large elm there may be given to the 
atmosphere as much as several tons in the same period. The amount, 
however, varies very considerably with the atmospheric conditions. It is 
a fact of common observation that large trees, such as the oak, growing 
in cultivated fields, so completely take up the moisture from the earth 
that the corn or other crop fails to mature for a distance of many yards 
from them. 
In a forested region the approach of a low barometric area, with its 
accompanying high temperature conditions, in accordance with the laws 
of vaporization, causes a corresponding increase of evaporation from the 
