erimental knowledge, and base future work
upon such experience. He knows that he cannot afford to cultivate wet
land, and the problem before him is to leave it to produce what grass
it can produce, sell it, or find profit in drainage. He has the
experience of others that investment in drainage is more satisfactory
than most other investments, if land has any natural fertility. He has
assurance that debt incurred for drainage is the safest kind of debt an
owner of wet land can incur. He has a right to expect profit from the
undertaking, and he can begin the work in a small way, if an outlet is
at hand, and learn what return may be expected from further investment.
Almost without fail will he become an earnest advocate of
underdrainage.

[Illustration: Drain tile.]

Where Returns are Largest.--The total area of land needing drainage is
immense. Swamps form only a small part of this area. Yields of much old
farm land are limited by the excess of water during portions of the
year. As land becomes older, the area needing drainage increases.

The owner of wet land does well to gain his first experience in a field
where a swale or other wet strip not only fails to produce a full crop,
but limits the yield of the remainder of the field by delaying planting
and cultivation. This double profit often is sufficient to repay cost
in a single year.

Material for the Drains.--Doubtless there are places and times when
stone, or boards, or brush should be used in construction of
underdrains, but they are relatively few in number. Such underdrains
lack permanency, as a rule, though some stone drains are effective for
a long time. If drain tile can be obtained at a reasonable price, it
should be used even in fields that have an abundance of stone. Its use
requires less labor than that of stone, and when properly laid on a
good bottom, it continues effective. There is no known limit to the
durability of a drain made of good tile.

The Outlet.--The value of any drainage system is dependent upon the
outlet. Its location is the first thing to be determined. If the land
is nearly flat, a telescope level should be used to determine
elevations of all low points in the land to be drained. The outlet
should permit a proper fall throughout the length of the system, and it
should not require attention after the work is completed. If it is in
the bank of a stream or ditch, it should be above the normal level of
the water in the stream. In times