Clay Loam 50 "
Pure Clay 70 "

Mr. Shedd, of Boston, gives the result of a recent experiment of his own
on this point. He writes thus:

"I have made an experiment with a soil of ordinary tenacity, to
ascertain how much water it would hold in suspension, with the
following result: One cubic foot of earth held 0.4826434 cubic feet
of water; three feet of dry soil of that character will receive
1.44793 ft. vertical depth of water before any drains off, or
seventeen and three-quarter inches, equal to nearly six month's
rain-fall. One cubic foot of earth held 3.53713 gallons of water,
or if drains are three feet deep, one square foot of surface would
receive 10.61 gallons of water, before saturation. Other soils
would sustain a greater or less quantity, according to their
character."

Besides this power of retaining water, when brought into contact with
it, the soil has, in common with other porous bodies, the power of
drawing up moisture, or of absorbing it, independent of gravitation, or
of the weight of the water which aids to carry it down into the soil.
This power is called _capillary attraction_, from the hair-like tubes
used in early experiments. If very minute tubes, open at both ends, are
placed upright, partly immersed in a vessel of water, the water rises in
the tubes perceptibly higher than its general surface in the vessel. A
sponge, from which water has been pressed out, held over a basin of
water, so that its lower part touches the surface, draws up the water
till it is saturated. A common flower-pot, with a perforated bottom, and
filled with dry earth, placed in a saucer of water, best illustrates
this point. The water rises at once to a common level in the pot and
outside. This represents the water-table in the soil of our fields. But,
from this level, water will continue to rise in the earth in the pot,
till it is moistened to the surface, and this, too, is by capillary
attraction.

The tendency of water to ascend, however, is not the same in all soils.
In coarse gravelly soils, the principle may not operate perfectly,
because the interstices are too large, the weight of the water
overcoming the power of attraction, as in the cask of stones or shot. In
very fine clay, on the other hand, although it be absorptive and
retentive of water, yet the particles are so fine, and the spaces
between them so small, that this attrac