Marcu 28, 1884.] 
feel much honored in receiving this award on behalf 
of Professor Lesquereux. His valuable researches 
not only contribute systematic descriptions of the 
American secondary and tertiary floras, but furnish 
almost the only data for comparing those floras with 
the plant-life from similar strata on this side of the 
Atlantic. All Professor Lesquereux’s work is marked 
by such exactness and care, that I am glad we are 
thus able to honor it, and offer assistance in its 
progress. ; 
THE DIFFICULTY OF PREVENTING 
LHE OBTO FLOODS. 
WILLIAM E. MERRILL, lieutenant-colonel U.S. 
engineers, in charge of the government improvements 
in the Ohio River, has, at the request of the editor 
of the Cincinnati commercial gazette, made public his 
views respecting the causes of the Ohio floods, and 
discussed the possibility of their mitigation in a letter 
published in the issue of March 8 of that journal. 
In attempting to estimate the influence of forests, he 
says, experience has proved that the clearing and cul- 
tivation of level land have comparatively small effect 
upon floods, and may be left out of account: disastrous 
effects follow only when the hill and mountain sides 
are put undercultivation. The evil results of denud- 
ing the hills of trees are then illustrated by references 
to Spain, Palestine, Greece, parts of Italy and France, 
and the good results of reforesting the slopes of the 
French Alps noted. 
Above Cincinnati the watershed drained by the 
Ohio comprises the western third of Pennsylvania, 
the whole state of West Virginia excepting four 
counties, the eastern part of Kentucky, and nearly 
the entire state of Ohio. Now, leaving out of consid- 
eration the more level portions of this area, the ques- 
tion is, whether its hilly and mountainous parts have 
been cleared of forests to such an extent as to mate- 
rially affect its capacity to retain the rainfall, and so 
to call for legislative action to prevent greater calami- 
ties in the future. Col. Merrill answers this question 
emphatically in the negative. Speaking from an 
extended personal knowledge of the states of Penn- 
sylvania, West Virginia, and Kentucky, which com- 
prise the hilly portion of the Ohio basin, he says we 
are very far from having attained that state of forest 
destruction which would require the intervention of 
the government for the protection of the river-valleys 
in this manner. Any one who travels on the rail- 
roads which cross the Alleghanies sees that the coun- 
try is still heavily wooded, while away from the lines 
of the railroad it is still a wilderness, except in a few 
isolated valleys. Even the removal of the merchant- 
able timber from the country would do no especial 
damage, provided the underbrush and smaller trees 
were left to protect the soil. We thus far have no 
sure ground, he remarks, for asserting that man’s 
interference has had any marked influence upon the 
discharge of the Ohio. 
In sharp contrast with these views of Col. Merrill 
is an article on forests and floods in the New York 
independent for March 6 (p. 30), by Mr. N. H. Egles- 
SCIENCE. 
385 
ton of Washington, D.C., in which the basis of argu- 
ment seems to be furnished by the map prepared by 
Professor Sargent to illustrate the census returns in 
regard to the condition of the forests, and more par- 
ticularly by a careful examination of the amount of 
woodland now existing in the state of Olio as com- 
pared with that of twenty years ago. 
As the state is not much of it hilly, the argument 
appears in so far to be inconclusive, although the 
author states and explains the popularly accepted 
theory of the controlling influence of forests with 
great skill, and without hesitation ascribes the Ohio 
floods to their destruction. But Col. Merrill very 
pertinently remarks that the traditions of the abo- 
rigines show that even the great flood of 1884 was 
equalled by floods which occurred before white man’s 
axe felled a single tree in the valley of the Ohio. 
Whatever may be thought of the relative value of 
opinion upon this question, there is no doubt that 
Col. Merrill speaks as an expert and an authority 
when he treats the problem of controlling the surplus 
waters of the Ohio by artificial means. He says, the 
idea that it is possible to build a number of reservoirs 
in the mountains to store up water during freshets, 
and let it out during the scarcity of summer, is an old 
one, and one which has been discussed and aban- 
doned in case of various European rivers. It was, 
moreover, advocated by the able engineer, Charles 
Ellet,-jun., and vigorously pressed upon the atten- 
tion of Congress. When the improvement of the 
Ohio was taken in hand by the government, after 
the close of the civil war, this scheme was practically 
investigated by W. Milnor Roberts, whose long engi- 
neering experience in railroad and canal construction 
in western Pennsylvania, and consequent familiarity 
with its topography, peculiarly fitted him for this 
work. After an exhaustive examination of possible 
sites, and estimate of cost of retaining reservoirs, 
which will be found in detail in his report to the 
chief of engineers under the date of April 30, 1870, 
he concludes thus: ‘‘ My own careful investigations 
of the subject of controlling the floods of the Ohio 
by means of artificial reservoirs, which were made 
in 1857, satisfied my mind conclusively that such con- 
trol by human means, attainable within practicable 
limits of cost, is impossible.’’ 
Mr. Roberts then examined another question, which 
was the practicability, not of controlling the floods at 
all, but of simply storing sufficient water to provide 
a supply to supplement the scarcity of the summer 
to such an extent that the summer flow at Wheel- 
ing should not fall below six feet. The reservoirs 
required to accomplish this were estimated to have a 
capacity of not less then a hundred and fifty billion 
cubic feet, and they must store the drainage from a 
watershed of not less than thirty-six hundred square 
miles. The estimated cost of accomplishing this 
with thirty reservoirs was sixty million dollars, a sum 
out of all proportion to the advantage to be derived 
from the improvement. Moreover, the dangers at- 
tendant upon such reservoirs are too great to justify 
the construction of even the few reservoirs required 
to secure a navigable stage of water, to say nothing 
