DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 437 
The writer does not belittle evaporation and local run-off. He brings mr. McMath. 
underground storage forward that it may have its proper place in the 
consideration of the vital question. 
Considering the subsoil and underlying rocks as a sponge lying 
below the humus, the influence of forests on stream flow depends at 
least partly on whether they hold the water of rains and melted snow 
within reach of the sponge longer than denuded waste lands or culti- 
vated fields. An infinite variety of conditions must affect the question; 
the only answer that may be given is an averaged result. 
The author, in the first of his seven summing-up propositions, says: 
“The bed of humus and débris that develops under forest cover re- 
tains precipitation during the summer season, or moderately dry periods 
at any time of the year, more effectually than do the soil and rocks of 
deforested areas similarly situated.” 
The writer is content to accept this statement as the grand averaged 
fact, and thinks it a verdict in favor of forests. 
The conservation and utilization of Nature’s resources are the 
special province of engineers. Now that the subject has come to the 
front, engineers would be very remiss if they failed to press forward* 
in the discussion. They should not surrender the field to the horde 
of fakirs who rush into any discussion which promises to receive 
popular attention. 
As a check and antidote to the follies of fakirs, Colonel Chittenden’s 
paper and its discussion are valuable and timely. 
H. F. Laspette, M. Am. Soc. C. E. (by letter).—In point of timeli- Mr. Labelle. 
ness and completeness this paper is facile princeps; the question of the 
influence of forests on the regimen of rivers through the control of 
rainfall has been presented to the Society in a most exhaustive manner. 
The paper brings this matter, which has assumed a national im- 
portance, before a body of men who, it is to be hoped, will discuss it 
exhaustively, and there is no doubt that the net result will be a 
clearer understanding of the complicated problems involved, which, 
so far, have for the most part remained without adequate solution. 
The most natural thing to do, in investigating the value of this 
theory, as advanced by the votaries of reforestation, is to confront it 
with the facts; if it explains all or a great majority of them, it can 
be confidently accepted; if it does not, it is not tenable. In order to 
investigate the matter the writer submits Table 15, in which he has 
arranged by decades the high waters given by the author in Table 1. 
The available data from the Susquehanna and Schuylkill water-sheds 
have been added. The last two water-sheds have been selected because, 
in the first, deforestation has been progressing at a high rate since the 
Fifties; in the second, little or no deforestation has occurred during 
the last 40 years. The figures in Table 15 are the means of the author’s 
figures for each successive decade; other periods are shown in brackets. 
