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40
A similar accident happened in 1742. The keeper of the Round Tower
at St. Martin's crammed 28 people into a room 6 feet square, and not quite
6 feet high, and 4 were suffocated.
Cause III. Deficient or Impure Supply of Water.
The paramount necessity for an abundant supply of pure water, both for
internal use and for purposes of cleanliness, cannot for a moment be questioned.
The skin being the organ by which much noxious matter is eliminated
from the body, and upon which the human being depends for the regulation
of its temperature, it is of the greatest importance that every facility
should be afforded for strict cleanliness as a means of preserving health.
The source of all fresh water is rain, which comes to us in this way in
the purest form, containing as it does few or no salts; in fact, nothing more
than an admixture of a certain proportion of atmospheric air and a small
quantity of carbonic acid; and, according to Liebig, in the neighbourhood
of large towns, a minute quantity of ammonia.
Humboldt and Gay Lassac shew that the quantity of these gases equals
about one-twenty-fifth of the volume of the water; and that the proportion
of the oxygen to the nitrogen, instead of being as 21 to 79, as in
atmospheric air, is as 31 to 69.
I may here mention, that lead cisterns are unfit for storing rain water, as
from its containing carbonic acid, it is liable to form the poisonous carbonate
of lead. River or well water, from its containing salts, prevents this
by forming an insoluble crust or deposit on the surface of the lead, thus
preventing solution.
Well water is obtained from the natural filtration of rain through a more
or less pervious stratum, which being impeded in its descent by an impervious
substratum, is obtained by digging.
The quality materially depends upon the natural peculiarities of soil
through which it percolates, or with which it comes in contact; and is
liable to be contaminated in populous places by accidental admixture with
decomposing organic matter from leakage of drains, cesspools, sewers, &c.
These facts prove the necessity of properly securing with cement, not
only the sides of wells, but the entire extent of sewers and cesspools, the
receptacles of animal refuse and decomposition, instead of (as is frequently
the case), using mortar for the bottom of sewers and cement only
for the top; most cesspools not being cemented at all, in order that the
liquid parts may better percolate away, and require less frequent emptying.
No further illustration is wanted of this fact than the results which have
been proved to have taken place by a Commission which was appointed to
inquire into the causes of the fatality of asiatic cholera in the neighbourhood
of Golden-square, when it was ascertained beyond doubt, that the
frightful mortality was occasioned by the leakage of a single drain into a
well, which the inhabitants were in the habit of using for their supply of
water.
River water depends for its quality upon its source, and upon the nature
of the soil through which it passes.
If it passes through its whole course over a siliceous bed, it will be as a
general rule extremely pure, holding less salts in solution than well water,