DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLOW 457 
The essential point to be considered in the discussion of the rela- Mr. Pinchot. 
tion of forests to stream flow is this: What are the functions of the 
forest floor in the distribution of fallen rain ? 
Colonel Chittenden quotes at some length from the testimony of 
the speaker before the House Committee on the Judiciary, given 
February 27th, 1908, as follows: 
“T have in my hand here a photograph of a denuded hillside. 
After the forest has been removed rain falls on. that hillside and runs 
off rapidly, as the water I drop upon the photograph does now, and 
disappears instantly (illustrating). If, on the other hand, I place a 
forest cover on the hillside, that is exactly analogous in texture and 
effect with this piece of blotting paper, and drop the water slowly 
upon it, we would find that, instead of running off slowly at the bottom, 
the water is held (illustrating with blotting paper). Part of it runs 
off, but, as soon as the absorbent quality of the paper or the forest 
floor has time to take effect, the water is kept and drips gradually for 
a considerable length of time off the hill into the stream. This is an 
exact illustration of the way in which the forest controls the stream 
flow on that hillside.” : 
He continues: 
“Mr. Pinchot should have completed his illustration. He should 
have continued to sprinkle the paper long enough and heavily enough 
to have saturated the paper completely in order to show that the water 
would then flow from the paper as rapidly as from the uncovered area; 
and he should then have explained that this condition represents 
what always happens in the forest in times of great flood. Then he 
should have sprinkled thé paper intermittently in small quantities, 
and at such long intervals that the warm air of the room would 
evaporate all of the absorbed water, and that none whatever would flow 
away. He should then have explained that this condition represents 
what always takes place in the forest in times of great drought.” 
It is unfortunate that Colonel Chittenden should have stopped his 
quotation where he did. The paragraph continues unbroken: 
“The water which was in this piece of blotting paper on that steep 
slope remaining on the surface in this way for a considerable length 
of time, has an opportunity to run down into the soil, which is made 
permeable on the surface by the decay from the trees. One of the 
best-known effects of the humus under a forest is to render the top 
layer of the soil permeable and therefore to allow the water to sink 
into this forest: reservoir. Experiments made with the greatest care 
show that even a moderate bed of humus is able to hold some five 
times its own weight of water, and the water, being retained in that 
way, sinks gradually into the ground, and in this way the streams, 
instead of being made torrential, are made to flow much more regu- 
larly during the summer months. In other words, the effect of the 
forests, theoretically, from this experiment should be to diminish floods 
and maintain the low-water supply.” 
The speaker, on the preceding page of his testimony, had already 
