34 SCIENCE 
1816 this flow was estimated at 500,000,000 
gallons per day; in 1825 at 440,000,000; in 
1867 at 400,000,000, and in 1874 at 245,000,- 
000. In regard to this a commission of engi- 
neers say in their report in 1875: This re- 
markable decrease, not being accompanied by 
any great change in the rainfall, is no doubt 
largely due to the destruction of the forests in 
the drainage area, whereby the conservative 
action of the woodland has been lost, and the 
rainfall is permitted to descend rapidly to the 
bed and pass off in a succession of freshets.” 
The same bulletin (pp. 23-122) contains an 
elaborate “Review of Forest Meteorological 
Observations,” by Professor Mark W. Har- 
rington, who treats the data obtained at a 
considerable number of German stations by an 
original system of curves, bringing out the 
fact that the forest is cooler than the neigh- 
boring open country by several degrees. Being 
cooler, the dew-point is reached more quickly 
in the forest, when atmospheric conditions 
favor rain. The forest has (1) larger evapo- 
ration from widespread leafy surfaces and 
moist shaded soil, (2) cooler atmosphere from 
the local evaporation and (3) greater precipi- 
tation. Effects (1) and (8) so nearly com- 
pensate that there is hardly any difference in 
the total run-off from a given area, whether 
forested or not, but a great difference in the 
distribution of the flow in its annual fluc- 
tuation. 
The forest question is not a meteorological 
problem, but one of soils, erosion and drainage. 
In France enormous sums of money are being 
expended in a toilsome effort to undo the mis- 
takes of the past and to reforest the steep 
slopes. It seems strange that “eminent engi- 
neers ” should not be aware of these facts, and 
that our country must repeat all of these un- 
happy blunders of older nations without profit- 
ing by their experience. 
The French writer, Belgrand, quoted by 
Professor Swain, touches the heart of the 
matter when he says: “ The forests diminish 
very notably the volume of earthy matter 
transported by the streams, because they pre- 
vent the erosion of the earth, and it must be 
[N.S. Vou. XXXV. No. 888 
recognized that the impoverishment of the 
earth is much more to be deplored than the 
disasters caused by floods.” 
In the report of the chief of engineers, 
U.S. Army, for 1891 (p. 1107), Major Charles 
W. Raymond says: “The destruction of for- 
ests from the mountain crests and slopes of a 
watershed is undoubtedly the principal cause 
of the increase of the average magnitude of 
floods. The evidence collected during the 
last twenty-five years establishing this conclu- 
sion is well nigh overwhelming, and it is 
verified by repeated observations, not only in 
the mountains of Europe, but also in our own 
land”; and he refers to Colonel Torrelli, who 
“affirms as the result of careful observations 
that four fifths of the precipitation in forests 
is absorbed by the soil or detained by the 
surface of the ground to be gradually given 
up in springs and gentle rills, and only one 
fifth of the precipitation is delivered to the 
rivers rapidly enough to create floods. Upon 
the same slopes and surfaces denuded of their 
forests, the proportions are reversed. ... That 
the destruction of the forests in mountainous 
watersheds is followed by disastrous floods 
where previously such floods were unknown is 
not a matter of theory, opinion or probability, 
but it is a well-established physical fact.” 
“Tn France, Italy, Germany and Austria 
the systematic planting of mountain slopes as 
a means of restoring lost fertility and pre- 
venting the inundations following the de- 
struction of forests, is an established fact fol- 
lowed by results more satisfactory than the 
most sanguine anticipations.” 
The attempt to divert attention from the 
problem of the forest on the plea that it in- 
volves unsolved meteorological questions is an 
obscuring of the real question which concerns 
the soil. Governmental authority has been 
invoked ostensibly on account of increased 
difficulties and dangers to navigation of the 
rivers through neglect of their forest sources. 
Such perturbations of the streams do un- 
doubtedly result from deforestation of the 
mountain slopes, but of far greater impor- 
tance is the injury to the soil. The soil of 
