discharges all of the contents
above its mouth in a flow having sufficient force to carry forward not
only any solid matters which it may contain, but also any ordinary
obstructing accumulations in the drain below. The soil-pipe, carrying
the discharge of water-closets, should not be delivered into the
flush-tank, but at a point farther down the drain, so that any solid
matter it may deposit shall be swept forward by the next action of the
flush-tank. The more often the flush-tank is filled, and the greater the
proportion of its water to its impurities, the more efficient will be
its action. Therefore the slop closet waste leading from the upper
story, and even the outlet pipes of bathing-tubs, may with advantage be
delivered into it.

Although the flush-tank may receive no faecal matter, and even though the
housemaid's sink may not deliver into it, it will contain in the
discharge from the kitchen alone an amount of organic matter which will
produce offensive and dangerous gases by its decomposition. To provide
for the safe removal of these gases, a ventilating pipe should be
carried up to some point not near to any window or chimney-top.

From the time the sewers are ready for service no accumulation of faecal
matter or other organic household waste should be allowed to remain in
the village. All old vaults and cesspools should be filled with earth,
and disinfected by the admixture of lime with the upper layers of the
filling. The use of water-closets in all houses should be made
imperative; and the construction and arrangement of soil-pipes and of
all outlets should be regulated by the health authorities.

It is not worth while here to discuss the details of the construction
of water-closets and other interior plumbing work, except with reference
to soil-pipes and such drains as may deliver the outflow of soil-pipes
to the public sewer. The soil-pipe should be of cast iron, carefully
jointed with lead, not less than four inches in diameter, and carried by
the straightest course possible up through the roof and generally higher
than the ridge-pole. Its open top must not be near any window, and if
within ten feet of a chimney it should be at least one foot below the
level of the top of that chimney. There should be no trap in the
soil-pipe, and no trap in a private drain between the outlet of the
soil-pipe and the sewer. The reasons for this rule are twofold:--

1. No matter what amount of water may be used for flus