uch less in quantity and much more regular than in this
country, yet it is believed that the use of two-inch pipes will be found
abundantly sufficient for the admission and conveyance of any quantity
of water that it may be necessary to carry off by drainage in common
soils. In extraordinary cases, as where the land drained is a swamp, or
reservoir for water which falls on the hills around, larger pipes must
be used.

In many places in England "tops and bottoms," or horse-shoe tiles, are
still preferred by farmers, upon the idea that they admit the water more
readily; but their use is continued only by those who have never made
trial of pipes. No scientific drainer uses any but pipes in England, and
the million of acres well drained with them, is pretty good evidence of
their sufficiency. In this country, horse-shoe tiles have been much used
in Western New York, and have been found to answer a good purpose; and
so it may be said of the sole-pipes. Indeed, it is believed that no
instance is to be found on record in America of the failure of tile
drains, from the inability of the water to gain admission at the joints.

It may be interesting in this connection to state, that water is 815
times heavier than air. Here is a drain at four feet depth in the
ground, filled only with air, and open at the end so that the air can go
out. Above this open space is four feet of earth saturated with water.
What is the pressure of the water upon the tiles?

Mr. Thomas Arkell, in a communication to the Society of Arts, in
England, says--

"The pressure due to a head of water four or five feet, may be
imagined from the force with which water will come through the
crevices of a hatch with that depth of water above it. Now, there
is the same pressure of water to enter the vacuum in the pipe-drain
as there is against the hatches, supposing the land to be full of
water to the surface."

It is difficult to demonstrate the truth of this theory; but the same
opinion has been expressed to the writer by persons of learning and of
practical skill, based upon observations as to the entrance of water
into gas pipes, from which it is almost, if not quite, impossible to
exclude it by the most perfect joints in iron pipes. Whatever be the
theory as to pressure, or the difficulties as to the water percolating
through compact soils to the tiles, there will be no doubt left on the
mind of any one, after one experiment tri