nish the dam in six
hours should commence the work a little before dead low-water, and, (with
the aid of wheelbarrows, if necessary,) throw the earth in rapidly
_behind_ the row of stakes and fascines, giving the dam sufficient width
to resist the pressure of the water from without, and keeping the work
always in advance of the rising of the tide, so that, during the whole
operation, none of the filling shall be washed away by water flowing over
its top.

If the creek has a sloping bottom, the work may be commenced earlier,--as
soon as the tide commences to recede,--and pushed out to the center of the
channel by the time the tide is out. When the dam is built, it will be
best to heavily sod, or otherwise protect its surface against the action
of heavy rains, which would tend to wash it away and weaken it; and the
bed of the creek should be filled in back of the dam for a distance of at
least fifty yards, to a height greater than that at which water will stand
in the interior drains,--say to within three feet of the surface,--so that
there shall never be a body of water standing within that distance of the
dam.

This is a necessary precaution against the attacks of muskrats, which are
the principal cause of the insecurity of all salt marsh embankments. It
should be a cardinal rule with all who are engaged in the construction of
such works, never to allow two bodies of water, one on each side of the
bank to be nearer than twenty-five yards of each other, and fifty yards
would be better. Muskrats do not bore through a bank, as is often
supposed, to make a passage from one body of water to another, (they would
find an easier road over the top); but they delight in any elevated mound
in which they can make their homes above the water level and have its
entrance beneath the surface, so that their land enemies cannot invade
them. When they enter for this purpose, only from one side of the dyke,
they will do no harm, but if another colony is, at the same time, boring
in from the other side, there is great danger that their burrows will
connect, and thus form a channel for the admission of water, and destroy
the work. A disregard of this requirement has caused thousands of acres of
salt marsh that had been enclosed by dykes having a ditch on each side,
(much the cheapest way to make them,) to be abandoned, and it has induced
the invention of various costly devices for the protection of embankments
against these attacks.(27)