
ing industry more than keep pace with the substitution of other materi- 
als, and a rising price of wood is likely to be the resuit. 
But forests occupy an entirely different position from all other forms 
of natural wealth, and a far more fundamental one. They determine, 
to a very large extent, climatic and hygienic conditions, and, through 
these, the prosperity of industry and the distribution of disease and 
health. The functions of forests in modifying climate and soil are so 
fully and ably presented in the various reports and bulletins of the De- 
partment of Agriculture, and in the proceedings of the various Forestry 
Associations, that the merest summary of the important facts will suffice 
for our present purpose. 
Whether the presence of forests actually inereases the total amount 
of rain-fall within any great region may still be a subject for dispute, 
but all authorities agree that forests produce a much more equable dis- 
tribution of moisture throughout the year than exists where they are not 
found. Ina treeless district, particularly if it be hilly, the rain glides 
off into the rivulets and into the rivers, scarcely moistening the ground 
below its surface. The burning rays of the sun, or the sweeping blasts 
of air, cause the rapid evaporation of what may remain here and there 
on the surface or may have penetrated a little way into the soil. A 
few hours after the rain there are almost no signs that rain has fallen 
at all. On the contrary, where there are forests the interlaced roots 
of the trees and the mass of leaves above them act as a sponge, which 
absorbs the water and holds it long enough to enable it to perform its 
service of quickening animal and vegetable life. The water oozes and 
trickles down through this spongy substance, and flows slowly away to 
feed the springs and streams. The modifying action of great forests 
on the distribution of moisture is both direct on the immediate region 
lying about them, and indirect on distant localities, owing to their influ- 
ence on the character of the streams and rivers which drain their areas. 
Where streams are not thus protected and modified at their sources 
by forests they may become the cause of almost as much injury as ben- 
efit. Owing to the fact that the water flows off so rapidly, the streams 
become at one time raging torrents, sweeping everything before them 
and inflicting an amount of damage which it requires much of the time 
elapsing between floods to make good, while at another they dwindle 
into insignificance, scarcely furnishing water enough for the flocks and 
herds along their banks. Where the forests have been cleared from 
the sources and banks of historic rivers the result has been an entire 
change in the character of the streams. The histery of the Rhine, 
Rhone and Danube, in this respect, is full of instruction for us, and if 
alternating periods of drought and disastrous floods can not always be 
directly traced to the removal of the forests, their aggravation and 
frequency has been shown, even in this country, to be due to such re- 
moval. 
This influence of forests on the character of our streams is a much 


