ucted, and to suggest how the danger of failure, by
means of them, may be obviated.

Let not enterprising readers be alarmed at such an array of
difficulties, for the more conspicuous they become, the less is the
danger from them.

_Obstruction by Sand or Silt._ Probably, more drains are rendered
worthless, by being filled up with earthy matter, which passes with
water through the joints of the tiles, than by every other cause.

Fine sand will pass through the smallest aperture, if there is a current
of water sufficient to move it, and silt, or the fine deposit of mud or
other earth, which is held almost in solution in running water, is even
more insinuating in its ways than sand.

Very often, drains are filled up and ruined by these deposits; and,
unless the fall be considerable, and the drain be laid with even
descent, if earth of any kind find entrance, it must endanger the
permanency of the work. To guard against the admission of everything but
water, lay drains deep enough to be beyond the danger of water bursting
in, in streamlets. Water should enter the drain at the bottom, by rising
to the level of the tiles, and not by sinking from the surface directly
to them. If the land is sandy, great care must be used. In draining
through flowing sand, especially if there be a quick descent, the
precaution of sheathing tiles is resorted to. That is done by putting
small tiles inside of larger ones, breaking joints inside, and thus
laying a double drain. This is only necessary, however, in spots of sand
full of spring-water. Next best to this mode, is the use of collars over
the joints, but these are not often used, though recommended for sandy
land.

At least, in all land not perfectly sound, be careful to secure the
joints in some way. An inverted turf, carefully laid over the joint, is
oftenest used. Good, clean, fine gravel is, perhaps, best of all. Spent
tan bark, when it is to be conveniently procured, is excellent, because
it strains out the earth, while it freely admits water; and any
particles of tan that find entrance, are floated out upon the water. The
same may be said of sawdust.

To secure the exit of earth that may enter at the joints, there should
be care that the tiles be smooth inside, that they be laid exactly in
line, and that there be a continuous descent. If there be any place
where the water rises in the tiles, in that place, every particle of
sand, or other matter heavier than water, will be l