246 FORESTS, RESERVOIRS, AND STREAM FLOW 
mitted to no theory, as such, and his mind is entirely open to convic- 
tion upon any point in which his opinions may be shown to be errone- 
ous. His sympathies are wholly on the side of the present movement 
for the conservation of our natural resources, and, so far as this paper 
takes issue with certain tendencies of that movement, it is only for 
the purpose of inquiring whether such tendencies are not really inim- 
ical to the cause to which they pertain. 
With this preliminary statement, the writer will take up the first 
part of his paper, viz., the influence of forests upon stream flow. 
Forests AND STREAM FLow. 
The commonly accepted opinion is that forests have a beneficial 
influence on stream flow: 
(1) By storing the waters from rain and melting snow in the bed 
of humus that develops under forest cover, preventing their rapid 
rush to the streams and paying them out gradually afterward, thus 
acting as true reservoirs in equalizing the run-off. 
(2) By retarding the snow-melting in the spring and prolonging the 
run-off from that source. 
(3) By increasing precipitation. 
(4) By preventing erosion of the soil on steep slopes and thereby 
protecting watercourses, canals, reservoirs and similar works from 
accumulations of silt. 
There are many subsidiary influences, but, broadly stated, the above 
propositions cover the ground. They were first given general currency 
nearly forty years ago through the writings of Sir Gustav Wex, Chief 
Engineer on the Improvement of the Danube, whose treatise was trans- 
lated into English by the late General Weitzel, of the Corps of 
Engineers. -Wex’s theories were stoutly resisted at the time by many 
European engineers, and still find only a limited acceptance in the 
profession ;* though in the popular mind they have gained ground and 
in the United States are now accepted practically without question. 
To establish by definite proof the truth or falsity of these propo- 
sitions is an extremely difficult task. One would not think so, indeed, 
to judge from the cheerful confidence with which the popular. thought 
accepts them; but it is nevertheless so. The elements of the problem 
are so many and conflicting, the necessary evidence is so hard to get, 
* Almost simultaneously with the publication of Wex’s treatise, a similar work was 
published in France by M. F. Vallée taking exactly the opposite view of the question. 
