not to be at all disturbed by its pressure in passing over the
drains. It is by no means improbable that fields that have already been
drained in this country, may be, in the lifetime of their present
occupants, plowed and subsoiled by means of steam-power, and stirred to
as great a depth as shall be found at all desirable. But, in the present
mode of using the subsoil plow on land free from stones, a depth less
than three and a half or four feet would hardly be safe for the depth of
tile-drains.

TILES MUST BE LAID BELOW FROST.

This is a point upon which we must decide for our selves. There is no
country where drainage is practiced, where the thermometer sinks, as in
almost every Winter it does in New England, to 20 deg. below zero
(Fahrenheit).

All writers seem to assume that tile-drains must be injured by frost.
What the effect of frost upon them is supposed to be, does not seem very
clear. If filled with water, and frozen, they must, of course, burst by
the expansion of the water in freezing; but it would probably rarely
happen, that drainage-water, running in cold weather, could come from
other than deep sources, and it must then be considerably above the
freezing point. Still; we know that aqueduct pipes do freeze at
considerable depths, though supplied from deep springs. Neither these
nor gas-pipes are, in our New England towns, safe below frost, unless
laid four feet below the surface; and instances occur where they freeze
at a much greater depth, usually, however, under the beaten paths of
streets, or in exposed positions, where the snow is blown away. In such
places, the earth sometimes freezes solid to the depth of even six feet.
It will be suggested at once that our fields, and especially our wet
lands, do not freeze so deep, and this is true; but it must be borne in
mind, that the very reason why our wet lands do not freeze deeper, may
be, that they are filled with the very spring-water which makes them
cold in Summer, indeed, but is warmer than the air in Winter, and so
keeps out the frost. Drained lands will freeze deeper than undrained
lands, and the farmer must be vigilant upon this point, or he may have
his work ruined in a single Winter.

We are aware, that upon this, as every other point, ascertained facts
may seem strangely to conflict. In the town of Lancaster, among the
mountains in the coldest part of New Hampshire, many of the houses and
barns of the village are supplied with water broug