DISCUSSION : FOREST'S, RESERVOIRS, AND STREAM FLOW 513 
country of his mountains long after every vestige had disappeared Mr. Chitten- 
from the forests? Is it not true that these drifts and those higher 
up are a valuable resource long after the forest snows are gone? 
Mr. Willis states that the forest prevents from 20 to 40% of the 
rain from reaching the ground, depending upon conditions, The range 
is far wider than this. In the heat of summer, and with light showers, 
forests often hold back nearly 100% of precipitation; but when it 
comes to cold, heavy rains, from 1 to 3 in. in a day, and in deciduous 
forests where, for large portions of the year, there are no leaves on 
the trees, will any one venture to say that the forests prevent even 1% 
of the rain from reaching the ground? Yet it is with these very ex- 
tremes, as the writer has pointed out with emphasis, that our practical 
problems in river control are concerned. 
The writer would request those interested in this discussion to 
read carefully the quotation given from Ernst Ebermayer early in Mr. 
Willis’ discussion. It is a plain case of being unwilling to swallow one’s 
own doctrine. If that quotation means anything, it means that the forest 
prevents rain-water from penetrating the ground as readily as in the 
open country. But, “the forest on the mountain differs very de- 
cidedly from that on the plain in regard to water control,” and “a 
factor is introduced through which wooded mountain slopes receive 
a much larger amount of water than bare unwooded water-sheds.” 
What is the factor? What is the difference between mountain and 
plains forests in regard to water control? The writer maintains that, 
so far as there is any difference, it is all in favor of the plains forests. 
For the same forest bed, the retentive capacity diminishes as the slope 
inereases. Anyone can verify this fact by experiment. Far from the 
mountain forest being more effective in resisting run-off, the exact 
opposite is the truth. This example affdrds a pointed illustration of 
the straits to which forestry advocates are often put in trying to square 
the direct and necessary consequences of their reasoning with a con: 
-ventional theory which they are reluctant to oppose. 
In the following sentence Mr. Willis repeats that singular in- 
consistency which can arise only from trying to fit facts to a pre- 
conceived theory: 
“So retentive is the humus that, while it serves as a sponge to 
prevent run-off and transmit water to the ground reservoir, it does 
not give up much to storage, and yields its water-content only slowly. 
to the moderate influences of evaporation in the shade.” 
The direct inference from this is that the water stored in the 
forest bed will yield itself up to soak into the ground, but not to run 
off the surface of the ground. The water will follow the line of least 
resistance wherever that may be. Under certain conditions more will 
