the accumulated water has run off, say in 24 hours,
they may be covered up; if not, it may be necessary to remove them again,
and clean them by hand. When the work is undertaken it should be
thoroughly done, so that the expense of a new opening need not be again
incurred.

It is worse than useless to substitute larger sizes of tiles for those
which are taken up. The obstruction, if by silt, is the result of a too
sluggish flow, and to enlarge the area of the conduit would only increase
the difficulty. If the tiles are too small to carry the full flow which
follows a heavy rain, they will be very unlikely to become choked, for the
water will then have sufficient force to wash them clean, while if they
are much larger than necessary, a deposit of silt to one half of their
height will make a broad, flat bed for the stream, which will run with
much less force, and will be more likely to increase the deposit.

If the drains are obstructed by the roots of willows, or other trees, the
proprietor must decide whether he will sacrifice the trees or the drains;
both he cannot keep, unless he chooses to go to the expense of laying in
cement all of the drains which carry constant streams, for a distance of
at least 50 feet from the dangerous trees. The trouble from trees is
occasionally very great, but its occurrence is too rare for general
consideration, and must be met in each case with such remedies as
circumstances suggest as the best.

The gratings over the outlets of silt-basins which open at the surface of
the ground, are sometimes, during the first year of the drainage,
obstructed by a fungoid growth which collects on the cross bars. This
should be occasionally rubbed off. Its character is not very well
understood, and it is rarely observed in old drains. The decomposition of
the grass bands which are used to cover the joints of the larger tiles may
encourage its formation.

If the surface soil have a good proportion of sand, gravel, or organic
matter, so as to give it the consistency which is known as "loamy," it
will bear any treatment which it may chance to receive in cultivation, or
as pasture land; but if it be a decided clay soil, no amount of draining
will enable us to work it, or to turn cattle upon it when it is wet with
recent rains. It will much sooner become dry, because of the drainage, and
may much sooner be trodden upon without injury; but wet clay cannot be
worked or walked over without being more or less