239 INFLUENCE OF THE FOREST ON FLOODS. 
European foresters and public economists has been specially 
drawn to three points, namely: the influence of the forests on 
the permanence and regular flow of springs or natural foun- 
tains; on inundations by the overflow of rivers; and on the 
abrasion of soil and the transportation of earth, gravel, pebbles, 
and even of considerable masses of rock, from higher to lower 
levels, by torrents. There are, however, connected with this 
general subject, several other topics of minor or strictly local 
iuterest, or of more uncertain character, which I shall have 
occasion more fully to speak of hereafter. 
The first of these three principal subjects—the influence of 
the woods on springs and other living waters—has been 
already considered ; and if the facts stated in that discussion are 
well established, and the conclusions I have drawn from them 
are logically sound, it would seem to follow, as a necessary 
corollary, that the action of the forest is as important in dimin- 
ishing the frequency and violence of river-floods as in securing 
the permanence and equability of natural fountains; for any 
cause which promotes the absorption and accumulation of the 
water of precipitation by the superficial strata of the soil, to be 
slowly given out by infiltration and percolation, must, by pre- 
venting the rapid flow of surface-water into the natural channels 
of drainage, tend to check the sudden rise of rivers, and, con- 
sequently, the overflow of their banks, which constitutes what 
is called inundation. 
The surface of a forest, in its natural condition, can never 
pour forth such deluges of water as flow from cultivated soil. 
Humus, or vegetable mould, is capable of absorbing almost 
twice its own weight of water. The soil in a forest of decid- 
uous foliage is composed of humus, more or less unmixed, to 
the depth of several inches, sometimes even of feet, and this 
stratum is usually able to imbibe all the water possibly result- 
ing from the snow which at any one time covers, or the rain 
which in any one shower falls upon, it. But the vegetable 
mould does not cease to absorb water when it becomes satu- 
rated, for it then gives off a portion of its moisture to the min- 
