house do not fulfill this condition of immediate removal. They serve
for the retention of excremental and other matters. In a porous soil
it endangers the purity of the wells. The Indian cities afford
numerous examples of subsoil pollution. The Delhi ulcer was traced to
the pollution of the wells from the contaminated subsoil; and the soil
in many cities and villages is loaded with niter and salt, the
chemical results of animal and vegetable refuse left to decay for many
generations, from the presence of which the well water is impure.
There are many factories of saltpeter in India whose supplies are
derived from this source; and during the great French wars, when
England blockaded all the seaports of Europe, the First Napoleon
obtained saltpeter for gunpowder from the cesspits in Paris. Cesspools
are inadmissible where complete removal can be effected. Cesspits may,
however, be a necessity in some special cases, as, for instance, in
detached houses or a small detached barrack. Where they cannot be
avoided, the following conditions as to their use should be enforced:

1st. A cesspit should never be located under a dwelling. It should be
placed outside, and as far removed from the immediate neighborhood of
the dwelling as circumstances will allow. There should be a ventilated
trap placed on the pipe leading from the watercloset to the cesspit.
2d. It should be formed of impervious material so as to permit of no
leakage. 3d. It should be ventilated. 4th. No overflow should be
permitted from it. 5th. When full it should be thoroughly emptied and
cleaned out; for the matter left at the bottom of a cesspit is liable
to be in a highly putrescible condition.

Where a cesspit is unavoidable, perhaps the best and least offensive
system for emptying it is the pneumatic system. This is applicable to
the water closet refuse alone. The pneumatic system acts as follows: A