DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 389 
the lakes and streams. The special condition is one of incipient glacia- Mr. Willis. 
tion. From the glaciers of Mount Rainier one may learn what hap- 
pens when this condition develops extensive bodies of ice and snow, 
and Colonel Chittenden has kindly furnished an illustration—that 
of the White River (Fig. 1, Plate CX). This particular White River 
flows from the Emmons and White River glaciers which cover the 
eastern and north-eastern side of Mount Rainier, and its well-earned 
character of a bad stream is due to this fact, and not to the forest 
which once densely covered its lower course, but which is now severely 
cut and burned. Colonel Chittenden is unfortunate in not being 
acquainted, apparently, with the real character of the river. The 
writer was well acquainted with it at one time; he spent four years 
in these forests before they were touched by axe or fire (1881-84), and 
became familiar with the glacial and non-glacial streams by personal 
contact. The former are subject to well-known daily fluctuations, ris- 
ing in the morning and falling at night; the writer preferred to wade 
them early in the day. They also rise sharply under warm winds, and 
fall quickly when the air is chilled. The non-glacial brooks were 
uncompromisingly high and comparatively steady day and night, from 
some time in March until the snow was gone from under the forest cover. 
Thus the writer’s conclusion, based upon experience of snow con- 
ditions ranging from the mountains of North Carolina to the glaciers 
of Mount Rainier, is that the forest does exert a beneficial influence 
in retarding the melting and run-off of snows, even though, as hap- 
pens in certain areas, the snowfall is so great as to produce floods in 
spite of+the forest’s influence. 
Colonel Chittenden maintains that: 
“In periods of extreme summer heat, forests operate to diminish the 
run-off, because they absorb almost completely and give off in evapora- 
tion ordinary showers which, in the open country, produce a con- 
siderable temporary increase in the streams.” 
This fact, regarding the influence of forests upon light summer 
showers, might have been supplemented and the argument strengthened 
by stating that during the hot seasons forests also transpire a large 
amount of water which is taken from soil moisture, and these two facts 
together set a limit to the value of forests in regions of meager rain- 
fall. For instance, it is established by experience on the Great Plains, 
as well as in the orchards of Southern California, that wind-breaks 
may take more moisture from the soil than the crops near them can 
afford to loge, and the effect on the crops would be the effect on any 
spring in equally close proximity; but against this demand of the 
plant for moisture to carry on its physiological processes, must be set: 
the contribution which it has made at an earlier season to ground- 
water storage in excess of the contribution which would have resulted 
from bare ground. Here again recurs the question of slope and the 
