DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLOW 455 
those who read are to ascertain whether or not such conclusions are Mr. Johnston, 
based on fact or fancy. 
Precipitation problems have been studied by the officers of the 
United States Weather Bureau for many years, yet the writer has been 
unable to find, in any of their reports, anything which would lead to the 
belief that forests have any appreciable effect on rainfall. Until this 
important branch of the Government service shows that there is some 
relation between forests and precipitation, men with scientific attain- 
ments will not be in haste to conclude that forests are a great factor in 
influencing rain and snowfall. 
The writer has spent many months in the mountains of the West, 
and there the great problem is, not to prevent floods, because these are 
always of but local importance and of no great consequence, but to 
obtain the largest volume of water possible during the season when it 
is needed most for irrigation. Eastern streams are utilized for navi- 
gation and for power, as well as to furnish water for domestic purposes, 
but the problems in the West are different, because the needs and 
purposes there are different. 
The writer’s convictions have been established by observations and 
measurements covering a period of twenty years, and any one who 
doubts the truth of Colonel Chittenden’s conclusions in reference to 
the timbered areas in the mountains of the West, should visit any of 
the numerous ranges in the spring before the snows begin to melt. 
He will find the timbered areas covered with a blanket of snow. The 
bleak mountain tops above the timber line will also appear to he 
covered, but as he ascends the mountains he will find that the snow 
on the high rocky slopes lies in depths varying from a few inches to 
30 ft. and more. It will be found that it is warmer on the treeless 
slopes than it is in the forests while the sun is shining directly upon 
them; and when the sun is obscured, it is warmer under and among 
the trees. 
As the weather grows warmer, it will be found that the snow 
lying thinly on the exposed treeless areas disappears first, and the 
great drifts surrounding these areas of light snowfall above the 
timber line show but little tendency to change. The snows in the 
forests, being distributed in uniform depth, gradually settle, absorb- 
ing the water that results from melting, and freezing at the surface 
each night. Later in the season, the great drifts above the forests 
settle gradually and the streams are largely supplied from areas where 
the snowfall has been from 1 to 3 ft. in depth and where melting 
is not delayed by the shade of the trees. As the season advances, 
and some time between May 1st and June 15th, depending on the 
lateness of the spring, the snow in the forested areas begins to melt, 
and, as it is practically uniform in depth, the entire timbered area 
furnishes water to a stream and its tributaries at the same time, and, 
