ht in aqueducts from
the hills. We observed that the logs which form the conduit are, in many
places, exposed to view on the surface of the ground, sometimes partly
covered with earth, but generally very little protected. There has not
been a Winter, perhaps in a half century, when the thermometer has not
at times been 10 deg. below Zero, and often it is even lower than that. Upon
particular inquiry, we ascertained that very little inconvenience is
experienced there from the freezing of the pipes. The water is drawn
from deep springs in the mountains, and fills the pipes of from one to
two-inch bore, passing usually not more than one or two hundred rods
before it is discharged, and its warmth is sufficient, with the help of
its usual snow covering, to protect it from the frost.

We have upon our own premises an aqueduct, which supplies a cattle-yard,
which has never been covered more than two feet deep, and has never
frozen in the nine years of its use. We should not, therefore, apprehend
much danger from the freezing of pipes, even at shallow depths, if they
carry all the Winter a considerable stream of spring-water; but in pipes
which take merely the surface water that passes into them by
percolation, we should expect little or no aid from the water in
preventing frost. The water filtering downward in Winter must be nearly
at the freezing point; and the pipes may be filled with solid ice, by
the freezing of a very small quantity as it enters them.

Neither hard-burnt bricks nor hard-burnt tiles will crumble by mere
exposure to the Winter weather above ground, though soft bricks or tiles
will scarcely endure a single hard frost. Too much stress cannot be laid
upon the importance of using hard-burnt tiles only, as the failure of a
single tile may work extensive mischief. Writers seem to assume, that
the freezing of the ground about the drains will displace the tiles, and
so destroy their continuity, and this may be so; though we find no
evidence, perhaps, that at three or four feet, there is any disturbance
of the soil by freezing. We dig into clay, or into our strong subsoils,
and find the earth, at three feet deep, as solid and undisturbed as at
twice that depth, and no indication that the frost has touched it,
though it has felt the grip of his icy fingers every year since the
Flood. With these suggestions for warning and for encouragement, the
subject must be left to the sound judgment of the farmer or engineer
upo