curacy.

"To one advantage which is derived from the use of collars we have
not yet adverted--the increased facility with which free water
existing in the soil can find entrance into the conduit.

"The collar for a one and a half inch pipe has a circumference of
nine inches. The whole space between the collar and the pipe, on
each side of the collar, is open, and affords no resistance to the
entrance of water: while, at the same time, the superincumbent arch
of the collar protects the junction of two pipes from the intrusion
of particles of soil. We confess to some original misgivings, that
a pipe resting only on an inch at each end, and lying hollow, might
prove weak, and liable to fracture by weight pressing on it from
above; but the fear was illusory. Small particles of soil trickle
down the sides of every drain, and the first flow of water will
deposit them in the vacant space between the two collars. The
bottom, if at all soft, will also swell up into any vacancy.
Practically, if you re-open a drain well laid with pipes and
collars, you will find them reposing in a beautiful nidus, which,
when they are carefully removed, looks exactly as if it had been
moulded for them."

As to the danger of breaking the pipes, which might well be apprehended,
we found by actual experiment, at the New York Central Park, that a
one-inch Albany pipe resting on collars upon a floor, with a bearing at
each end of but one inch, would support the weight of a man weighing 160
pounds, standing on one foot on the middle of the pipe.

Mr. Parkes sums up his opinion upon the subject of collars, in these
words:

"It may be advisable for me to say, that in clays, and other
clean-cutting and firm-bottomed soils, I do not find collars to be
at all necessary; but that they are essential in all sandy, loose,
and soft strata."

In draining in the neighborhood of trees, collars are also supposed to
be of great use in preventing the intrusion of roots into the pipes,
although it may be impossible, even in this way, to exclude the roots of
water-loving trees.

From the most careful inquiry that the writer was able to make, as to
the practice in England, he is satisfied that collars are not generally
used there in the drainage of clays, but that the pipes are laid in
openings shaped for them at the bottom of the drains, with a tool