ch tracts, the first inquiry is as to the
source of the water. What makes the land too wet? Is it the direct fall
of rain upon it; the influx of water by visible streams, which have no
sufficient outlet; the downflow of rain and snow water from the
neighboring hills; or the bursting up of springs from below?

Examine and decide, which and how many, of these four sources of
moisture, contribute to flood the tract in question. We assume, that the
swamp is in a basin, or, at least, is the lowest land of the
neighborhood. The three or four feet of rain water annually falling upon
it, unless it have an outlet, must make it a swamp, for there can
usually be no natural drainage downward, because the swamp itself is the
lowest spot, and no adjacent land can draw off water from its bottom. Of
course, there is lower land towards the natural outlet, but usually this
is narrow, and quite insufficient to allow of drainage by lateral
percolation. Then, always, more or less water must run upon the surface,
or just below it, from the hills, and usually, a stream is found in the
swamp, if none pours into it from above.

The first step is a survey, to ascertain the fall over the whole, and
the next, to provide a deep and sufficient outlet. Here, we must bear in
mind a peculiarity of such lands. All land subsides, more or less, by
drainage, but the soils of which we are speaking, far more than any
other. Marsh and swamp lands often subside, or _settle_, one or two
feet, or even more. Their soil, of fibrous roots, decayed leaves, and
the like, almost floats; or, at least, expands like a sponge; and when
it is compacted, by removing the water, it occupies far less space than
before. This fact must be kept in mind in all the process. The outlet
must be made low enough, and the drains must be made deep enough, to
draw the water, after the subsidence of the soil to its lowest point.

If a natural stream flow through, or from, the tract, it will usually
indicate the lowest level; and the straightening and clearing out of
this natural drain, may usually be the first operation, after opening a
proper outlet. Then a catch-water open drain, just at the junction of
the high and low land, entirely round the swamp, will be necessary to
intercept the water flowing into the swamp. This water will usually be
found to flow in, both on the surface, and beneath it, and in greater or
less quantities, according to the formation of the adjacent land. This
ca