cross its flow. Indeed, the whole theory as to the distance
of drains apart, rests upon the idea, that the limit to which drains may
be expected effectually to operate, is at most but two or three rods.

Whether, in a particular case, a header alone will be sufficient to cut
off the flow of water from the higher land, or whether, in addition to
the header, an open catch-water may be required, must depend upon the
quantity of water likely to flow through or upon the land. An
under-drain might be expected to absorb any moderate quantity of what
may be termed drainage-water, but it cannot stop a river or mill-stream;
and if the earth above the tiles be compact, even water flowing through
the soil with rapidity, might pass across it. If there is reason to
apprehend this, an open ditch might be added to the header; or, if this
is not considered sufficiently scientific or in good taste, a tile-drain
of sufficient capacity may be laid, with the ditch above it carefully
packed with small stones to the top of the ground. Such a drain would be
likely to receive sand and other obstructing substances, as well as a
large amount of water, and should, for both reasons, be carried off
independently of the small drains, which would thus be left to discharge
their legitimate service.

Where it is thought best to connect an open, or surface drain, with a
covered drain, it will add much to its security against silt and other
obstructions, to interpose a trap or silt-basin at the junction, and
thus allow the water to pass off comparatively clean. Where, however,
there is a large flow of water into a basin, it will be kept so much in
motion as to carry along with it a large amount of earth, and thus
endanger the drain below, unless it be very large.

DISTANCES APART, OR FREQUENCY OF DRAINS.

The reader, who has studied carefully the rival systems of "deep
drainage" and "thorough drainage," has seen that the distance of drains
apart, is closely connected with that controversy. The greatest variety
of opinion is expressed by different writers as to the proper distances,
ranging all the way from ten feet apart to seventy, or even more.

Many English writers have ranged themselves on one side or the other of
some sharp controversy as to the merits of some peculiar system. Some
distinguished geologist has discovered, or thinks he has, some new law
of creation by which he can trace the underground currents of water; or
some noble noble lord