ca, as in Great Britain, one half the cultivable land require
drainage, or even if but a tenth of that half require it, the subject is
of vast importance, and it is no less important for us to apprehend
clearly what part of our land does _not_ require this expenditure, than
to learn how to treat properly that which does require it.

To resume the inquiry, what lands require drainage? it may be answered--

ALL LANDS OVERFLOWED IN SUMMER REQUIRE DRAINAGE.

Lands overflowed by the regular tides of the ocean require drainage,
whether they lie upon the sea-shore, or upon rivers or bays. But this
drainage involves embankments, and a peculiar mode of procedure, of
which it is not now proposed to treat.

Again, all lands overflowed by Summer freshets, as upon rivers and
smaller streams, require drainage. These, too, usually require
embankments, and excavations of channels or outlets, not within the
usual scope of what is termed thorough drainage. For a further answer to
the question--what lands require drainage? the reader is referred to the
chapters which treat of the effect of drainage upon the soil.

SWAMPS AND BOGS REQUIRE DRAINAGE.

No argument is necessary to convince rational men that the very
extensive tracts of land, which are usually known as swamps and bogs,
must, in some way, be relieved of their surplus water, before they can
be rendered fit for cultivation. The treatment of this class of wet
lands is so different from that applied to what we term upland, that it
will be found more convenient to pass the subject by with this allusion,
at present, and consider it more systematically under a separate head.

ALL HIGH LANDS THAT CONTAIN TOO MUCH WATER AT ANY SEASON, REQUIRE
DRAINAGE.

Draining has been defined, "The art of rendering land not only so free
of moisture as that no superfluous water shall remain in it, but that no
water shall remain in it so long as to injure, or even retard the
healthy growth of plants required for the use of man and beast."

Some plants grow in water. Some even spring from the bottom of ponds,
and have no other life than such a position affords. But most plants,
useful to man, are drowned by being overflowed even for a short time,
and are injured by any stagnant water about their roots. Why this is so,
it is not easy to explain. Most of our knowledge on these points, is
derived from observation. We know that fishes live in water, and if we
would propagate them, we prepare p