DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLOW 821 
examination and report upon the best method of protecting the City Mr. Colling- 
of Elmira against such floods. es 
A careful survey was made of about three miles of the river, with 
cross-sections every 100 ft., these being carried entirely across the 
flooded portion of the valley. : 
Having lived elsewhere for about 20 years previous to this, the writer 
was amazed at the extent of the changes in the stream. At one point 
it had widened from about 600 to about 1300 ft. All through this 
portion there were bars covered with black alder, and on the south 
bank there was a matted mass of alders, in some places 100 ft. wide. 
In early days there were no alders, and the land that had been cut 
away was rich and arable. 
At other points, over considerable areas, every particle of mould 
had been washed away, down to the hard clay, and the whole region 
was covered with coarse weeds. 
In a previous survey of another portion of the river, in a dry time, 
the stream practically disappeared in its gravelly bed. A gentleman 
living. on the Susquehanna, at Wyalusing, told the writer that his 
lands along the river, which he used to consider the best parts of his 
farm, were now so cut and gashed by the freshets that they had largely 
lost their value. Any person riding along one of the railroad lines 
through the valley can see the damage done by the river, often at 
points considerably distant from its main channel. These devastations 
seem to be increasing, and records of the flood heights, kept for 
many years at Elmira, indicate a tendency of the floods to be higher 
as the years roll on. 
To the writer’s mind, the cause is very plain. One of the streams 
heading into the Chemung is very steep, and, when the heavy woods 
were cut from its bank, the flood-waters were more rapidly concen- 
trated, and poured into the main stream, so that the time required 
for the flood from a heavy rain to reach Elmira was very much 
shortened. The writer’s recollection is that this time was reduced to 
one-half. The other two streams did their quota of damage, but not 
to the same extent. If this be true, the conclusion is irresistible: that 
the forests do act as powerful conservators and regulators of stream flow. 
The conclusions seem sound, from another point of view: Here 
is a stream flowing for centuries, having a uniform regimen, with 
fairly uniform section and smooth banks up to, say, 50 years ago, 
showing, up to that time, but few signs of destruction from floods. 
Within 20 years there is a complete change, and a beautiful stream is 
transformed into an irregular, wilful, destructive thing. 
If the cutting of the timber did not do it, what was it? 
Tuomas P. Roserts, Esq.* (by letter).—This paper covers the sub- Mr. Roberts. 
ject in a very broad and comprehensive manner. 
* Civil Engineer U.S. Engineer's Office Pittsburg, Pa. 
