438 
ABSORPTION AND INFILTRATION. 
reserve for springs, wells, and rivers which conld not be sup¬ 
plied by any amount of summer rain.” “ This latter—useful, 
indeed like dew, to vegetation—does not penetrate the soil 
and accumulate a store to feed springs and to he brought up 
by them to the open air.” * This conclusion, however applic¬ 
able it may be to the climate and soil of France, is too broadly 
stated to be accepted as a general truth, and in countries 
where the precipitation is small in the winter months, familiar 
observation shows that the quantity of water yielded by deep 
wells and natural springs depends not less on the rains of sum¬ 
mer than on those of the rest of the year, and, consequently, 
that much of the precipitation of that season must find its way 
to strata too deep to lose water by evaporation. 
The supply of subterranean reservoirs and currents, as well 
as of springs, is undoubtedly derived chiefly from infiltration, 
and hence it must be affected by all changes of the natural 
surface that accelerate or retard the drainage of the soil, or 
that either promote or obstruct evaporation from it. It has 
sufficiently appeared from what has gone before, that the spon¬ 
taneous drainage of cleared ground is more rapid than that of 
the forest, and consequently, that the felling of the woods, as 
well as the draining of swamps, deprives the subterranean 
waters of accessions which would otherwise be conveyed to 
them by infiltration. The same effect is produced by artificial 
contrivances for drying the soil either by open ditches or by 
underground pipes or channels, and in proportion as the sphere 
of these operations is extended, the effect of them cannot fail 
to make itself more and more sensibly felt in the diminished 
supply of water furnished by wells and running springs.f 
* Etudes et lectures , vi, p. 118. 
t “ The area of soil dried by draining is constantly increasing, and the 
water received by the surface from atmospheric precipitation is thereby 
partly conducted into new channels, and, in general, carried off more 
rapidly than before. "Will not this fact exert an influence on the condition 
of many springs, whose basin of supply thus undergoes a partial or com¬ 
plete transformation? I am convinced that it will, and it is important to 
collect data for solving the question.”— Beknhard Ootta, Preface to 
Paramelle, Quellenhunde (German translation), pp. vii, viii. 
