GEOGRAPHICAL EFFECTS OF DRAINING. 445 
the eulogiums of its advocates; but its extensive adoption 
appears to have been attended with some altogether unforeseen 
and undesirable consequences, very analogous to those which 
I have described as resulting from the clearing of the forests. 
The under-drains carry off very rapidly the water imbibed by 
the soil from precipitation, and through infiltration from neigh- 
boring springs or other sources of supply. Consequently, in 
wet seasons, or after heavy rains, a river bordered by artifi- 
cially feteied lands receives in a few hours, from superficial 
and from subterranean conduits, an accession of water which, 
in the natural state of the earth, would have reached it only 
by small instalments after percolating through hidden paths 
for weeks or even months, and would have furnished peren- 
nial and comparatively regular contributions, instead of swelling 
deluges, to its channel. Thus, when human impatience rashly 
ubstitutes swiftly acting artificial contrivances for the slow 
methods by which nature drains the surface and superficial 
strata of a river-basin, the original equilibrium is disturbed, 
the waters of the heavens are no longer stored up in the earth 
to be gradually given out again, byt are hurried out of man’s 
domain with wasteful haste ; and while the inundations of the 
river are sudden and disastrous, its current, when the drains 
have run dry, is reduced to a rivulet, it ceases to supply the 
power to drive the machinery for which it was once amply 
sufficient, and scarcely even waters the herds that pasture upon 
its margin. 
The water of subterranean currents and reservoirs, as well as 
that of springs and common wells, is doubtless principally fur- 
nished by infiltration, and hence its quantity must vary with 
every change of natural surface which tends to accelerate or 
to retard the drainage of the surface-soil. The drainage of 
marshes, therefore, and all other methods of drying the super- 
ficial strata, whether by open ditches or by underground tubes 
or drains, has the same effect as clearing off the forest in de- 
priving the subterranean waters of accessions which they would 
otherwise receive by infiltration, and in proportion as the sphere 
