uses had cess-pools beneath them, which were filled with the
accumulations of many years, while the sewers themselves were scarcely
less offensive. This condition resulted in a severe epidemic fever of a
very fatal character.

An examination instituted to discover the cause of the epidemic resulted
in the discovery of the facts set forth above, and there were removed from
the drains and cess-pools more than 550 loads of ordure. The evaporating
surface of this filth was more than 2000 square yards.

Since the new drainage, not only has there been no recurrence of epidemic
fever, but "a greater improvement in the general health of the population
has succeeded than might be reasonably expected in a small block of
houses, amidst an ill-conditioned district, from which it cannot be
completely isolated."

The principle which justifies the use of pipe sewers is precisely that
which has been described in recommending small tiles for agricultural
drainage,--_to wit_: that the rapidity of a flow of water, and its power to
remove obstacles, is in proportion to its depth as compared with its
width. It has been found in practice, that a stream which wends its
sluggish way along the bottom of a large brick culvert, when concentrated
within the area of a small pipe of regular form, flows much more rapidly,
and will carry away even whole bricks, and other substances which were an
obstacle to its flow in the larger channel. As an experiment as to the
efficacy of small pipes Mr. Hale, the surveyor, who was directed by the
General Board of Health of London to make the trial, laid a 12-inch pipe
in the bottom of a sewer 5 feet and 6 inches high, and 3 feet and 6 inches
wide. The area drained was about 44 acres. He found the velocity of the
stream in the pipe to be four and a half times greater than that of the
same amount of water in the sewer. The pipe at no time accumulated silt,
and the force of the water issuing from the end of the pipe kept the
bottom of the sewer perfectly clear for the distance of 12 feet, beyond
which point some bricks and stones were deposited, their quantity
increasing with the distance from the pipe. He caused sand, pieces of
bricks, stones, mud, etc., to be put into the head of the pipe. These were
all carried clear through the pipe, but were deposited in the sewer below
it.

It has been found by experiment that in a flat bottomed sewer, four feet
wide, having a fall of eight inches in one hundred feet, a st