502 DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 
Mr. Chitten- glance. . It applies only to hot weather and to the air near the surface 
* of the ground. It is certainly not true of the fall, winter, and spring 
seasons, when most of the rain and all the snow falls. It is probably 
not true even of summer storms of considerable duration. Whatever 
influence there is of this kind is small even in summer showers. The 
example, cited by a recent writer in Engineering News, of showers 
soaking the forests but leaving the clearings untouched—like Gideon’s 
fleece, saturated with dew while it is “dry upon all the earth beside”— 
requires something more than a bald statement to substantiate it. If 
there is any such tendency it may be questioned if it is not more than 
offset by the greater absorptive power of the forest than that of the 
open country at such times. 
It should be carefully borne in mind, in any discussion of this 
subject, that floods and low waters result primarily from the quantity 
and distribution of precipitation. It is rarely necessary to go beyond 
this simple fact for an explanation; but apparently because climate 
is still one of those natural phenomena over which Man has acquired 
no control, the tendency is to ignore it and attribute to other causes 
results for which it is alone responsible. The greatest discovery or 
advance in scientific knowledge, so far as the practical welfare of 
Mankind is concerned, that the world is likely ever to see (if it 
should see this) will be of some means of controlling the weather, and 
particularly precipitation. Many experiments have been made in this 
direction, but so far without appreciable success.* 
Proposition 7%. 
“The percentage of annual run-off to rainfall has been slightly in- 
creased by ‘deforestation and cultivation.” 
The writer submits this proposition simply as an expression of 
his own opinion, without many confirmatory data. The 20-year record 
of the Connecticut at Holyoke,t by Clemens Herschel, M. Am. Soc. 
C. E., seems to confirm it on that stream, though the period is short. 
The low-water discharge of the Ohio seems to be as great and possibly 
greater than formerly, particularly if there be included the very large 
consumption for human use which would otherwise get into that 
stream. The writer does not believe that there is any large increase in 
the percentage of run-off over that of former times, but he believes, 
in any event, that it has not diminished. 
* Though admittedly irrelevant, the interesting character of the following item justifies 
its insertion here, as another example of the old saying that ‘There is nothing new under 
the sun.” Everyone is familiar with the superstition (possibly it deserves a better name) 
that great battles produce rain. The vibrating effect upon the atmosphere of the multi- 
tudinous detonations of artillery is generally ascribed as the cause. Read this from 
Plutarch, who flourished 45-125 A.D. 
“It is an observation also, that extraordinary rains pretty generally fall after great 
battles; whether it be that some divine power thus washes and cleanses the polluted earth 
with showers from above, or that moisture and heavy evaporation, steaming forth from 
the blood and corruption, thickens the air, which naturally is subject to alterations from 
the smallest causes.” 
+ Transactions, Am. Soc. C. E., Vol. LVIII, p. 81. 
