are extracted from it, and held for the use of growing plants. Its
fresh air, and the air which follows the descent of the water-table,
carries oxygen to the organic and mineral parts of the soil, and hastens
the rust and decay by which these are prepared for the uses of vegetation.
The water itself supplies, by means of their power of absorption, the
moisture which is needed by the particles of the soil; and, having
performed its work, it goes down to the level of the water below, and,
swelling the tide above the brink of the dam, sets the drains running,
until it is all removed. In its descent through the ground, this water
clears the passages through which it flows, leaving a better channel for
the water of future rains, so that, in time, the heaviest clays, which
will drain but imperfectly during the first one or two years, will pass
water, to a depth of four or five feet, almost as readily as the lighter
loams.

Now, imagine the drains to be closed up, leaving no outlet for the water,
save at the surface. This amounts to a raising of the dam to that height,
and additions to the water will bring the water-table even with the top of
the soil. No provision being made for the removal of spring and soakage
water, this causes serious inconvenience, and even the rain-fall, finding
no room in the soil for its reception, can only lie upon, or flow over,
the surface,--not yielding to the soil the fertilizing matters which it
contains, but, on the contrary, washing away some of its finer and looser
parts. The particles of the soil, instead of being furnished, by
absorption, with a healthful amount of moisture, are made unduly wet; and
the spaces between them, being filled with water, no air can enter,
whereby the chemical processes by which the inert minerals, and the roots
and manure, in the soil are prepared for the use of vegetation, are
greatly retarded.

Instead of carrying the heat of the air, and of the surface of the ground,
to the subsoil, the rain only adds so much to the amount of water to be
evaporated, and increases, by so much, the chilling effect of evaporation.

Instead of opening the spaces of the soil for the more free passage of
water and air, as is done by descending water, that which ascends by
evaporation at the surface brings up soluble matters, which it leaves at
the point where it becomes a vapor, forming a crust that prevents the free
entrance of air at those times when the soil is dry enough to aff