partially broken; and, indeed, from various other causes, all of
which may occur in any practical case, unless great care is taken
to avoid it, and some of which may occur in almost any case.

"We have endeavored to so construct the tables that, in the
ordinary practice of draining, the discharge given may approximate
to the truth for a well laid drain, subject even to considerable
friction. The experiments of Mr. Smeaton, which we have adopted as
the basis of these tables, gave a less quantity discharged, under
certain conditions, than given under similar conditions by other
tables. This result is probably due to a greater amount of friction
in the pipes used by Smeaton. The curves of friction resemble, very
nearly, parabolic curves, but are not quite so sharp near the
origin.

"We propose, during the coming season, to institute some careful
experiments, to ascertain the friction due to our own drain-pipe.
Water can get into the drain-pipe very freely at the joints, as may
be seen by a simple calculation. It is impossible to place the ends
so closely together, in laying, as to make a tight joint on account
of roughness in the clay, twisting in burning, &c.; and the opening
thus made will usually average about one-tenth of an inch on the
whole circumference, which is, on the inside of a two-inch pipe,
six inches--making six-tenths of a square inch opening for the
entrance of water at each joint.

"In a lateral drain 200 feet long, the pipes being thirteen inches
long, there will be 184 joints, each joint having an opening of
six-tenth square inch area; in 184 joints there is an aggregate
area of 110 square inches; the area of the opening at the end of a
two-inch pipe is about three inches; 110 square inches inlet to
three inches outlet; thirty-seven times as much water can flow in
as can flow out. There is, then, no need for the water to go
through the pores of the pipe; and the fact is, we think, quite
fortunate, for the passage of water through the pores would in no
case be sufficient to benefit the land to much extent. We tried an
experiment, by stopping one end of an ordinary drain-pipe and
filling it with water. At the end of sixty-five hours, water still
stood in the pipe three-fourths of an inch deep. About half the
water first pu