arts have been demolished, and new wide
streets pierced through the town.

DRAINAGE OF LAND. The verb "to drain," with its substantives "drain" and
"drainage," represents the O. Eng. _dreahnian_, from the same root
found in "dry," and signifies generally the act of drawing off moisture
or liquid from somewhere, and so drinking dry, and (figuratively)
exhausting; the substantive "drain" being thus used not only in the
direct sense of a channel for carrying off liquid, but also figuratively
for a very small amount such as would be left as dregs. The term
"drainage" is applied generally to all operations involving the drawing
off of water or other liquid, but more particularly to those connected
with the treatment of the soil in agriculture, or with the removal of
water and refuse from streets and houses. For the last, see SEWERAGE;
the following article being devoted to the agricultural aspects of this
subject. See also the articles RECLAMATION OF LAND, CANAL, IRRIGATION,
RIVER ENGINEERING, WATER SUPPLY and (law) WATER RIGHTS.

Agricultural or field drainage consists in the freeing of the soil from
stagnant and superfluous water by means of surface or underground
channels. It may be distinguished from the draining of land on a large
scale which is exemplified in the reclamation of the English Fens (see
FENS). Surface drainage is usually effected by ploughing the land into
convex ridges off which the water runs into intervening furrows and is
conveyed into ditches. For several reasons this method is ineffective,
and, where possible, is now superseded by underground drainage by means
of pipe-tiles. Land is not in a satisfactory condition with respect to
drainage unless the rain that falls upon it can sink down to the minimum
depth required for the healthy development of the roots of crops and
thence find vent either through a naturally porous subsoil or by
artificial channels.

A few of the evils inseparable from the presence of overmuch water in
the soil may be enumerated. Wet land, if in grass, produces only the
coarser grasses, and many subaquatic plants and mosses, which are of
little or no value for pasturage; its herbage is late in spring, and
fails early in autumn; the animals grazed upon it are unduly liable to
disease, and sheep, especially, to foot-rot and liver-rot. In the case
of arable land the crops are poor and moisture-loving weeds flourish.
Tillage operations on such land are easily interrupted by r