At Tooting, thirteen hundred and ninety-
five pauper children were crowded into
a space which was large enough for
only five hundred. Sixty-four of these
children were attacked by cholera in one
night; and in a week a hundred and eighty
had died. This, because of overcrowding:
and of the scanty allowance of one hundred
cubic feet of air to each child, when five
hundred cubic feet is the smallest quantity
compatible with safety. In the Taunton
workhouse there were two hundred and
seventy-six inmates with sixty-eight cubic
feet of air for each. Cholera carried off sixty
in less than a week. In the county jail of
Taunton, where the criminals were allowed
from eight hundred and nineteen to nine
hundred and thirty-five cubic feet of air, not
a single case of cholera, nor even or diarrhœa,
occurred. At East Farleigh, in Kent, one
thousand people were assembled for hop-
picking. They were lodged in sheds, and had
about eighty cubic feet of air each to breathe.
Ninety-seven were struck down by cholera,
while in the same village another employer,
who had provided proper accommodation
for his work-people, did not lose one by
the epidemic. All through the overcrowded
streets of London, last year, the cholera
raged with violence; whilst in the more
open spaces, other sanitary conditions being
observed, not a case was recorded. People
have often said that no difference can be
detected in the analysation of pure and
impure air. This is one of the vulgar errors
difficult to dislodge from the public brain.
The fact is, that the condensed air of a
crowded room gives a deposit which, if allowed
to remain for a few days, forms a solid, thick,
glutinous mass, having a strong odour of
animal matter. If examined by the microscope,
it is seen to undergo a remarkable
change. First of all, it is converted into a
vegetable growth, and this is followed by the
production of multitudes of animalcules;
a decisive proof that it must contain organic
matter, otherwise it could not nourish
organic beings. This was the result arrived
at by Dr. Angus Smith, in his beautiful
experiments on the Air and Water of
Towns; wherein he showed how the lungs
and skin give out organic matter, which is in
itself a deadly poison, producing headache,
sickness, disease, or epidemic, according to
its strength. Why, if "a few drops of the
liquid matter, obtained by a condensation
of the air of a foul locality, introduced into
the vein of a dog, can produce death with
the usual phenomena of typhus fever,"
what incalculable evil must it not produce
on those human beings who breathe it
again and again, rendered fouler and less
capable of sustaining life with each breath
drawn! Such contamination of the air, and
consequent hot-bed of fever and epidemic, it is
easily within the power of man to remove.
Ventilation and cleanliness will do all, so far
as the abolition of this evil goes, and ventilation
and cleanliness are not miracles to be
prayed for, but certain results of common
obedience to the laws of God.

Besides this human contamination, the
atmosphere itself undergoes changes which
predispose it to the development and spread
of epidemics. Inversions of the seasons, long
droughts followed by heavy rain, mists, and
every form of continuous damp combined
with excessive heat, giving rise first, to
inordinate growths of the lower species of
vegetation, then to swarms of locusts, flies,
caterpillars, frogs, &c., and, as the sequence of
these antecedent conditions, dearth and
famine. Such, in all ages, have been the
signs and precursors of a coming year of
pestilence. During our own cholera epidemic,
the air has been observed to be wonderfully
still and stagnant, both by day and night;
and when the last plague visited Vienna,
there had been no wind for three months.
For several weeks, too, before the Great
Plague of London, the air had been so calm,
it could not stir a vane: and the "terrific
outbreak of cholera at Kurrachee, was
preceded for some days by such a stagnation
of the atmosphere, that an oppression scarcely
to be endured affected the whole population."
A deficiency of electriticy and a total absence
of ozone are among other meteorological
signs. Such atmospheric conditions
as these, brooding over the lanes and courts
of an uncleansed and over-populated city,
must necessarily produce a burst of
disease. Yet even then and thus, and
notwithstanding the tremendous force of
atmospheric influences, cleanliness, care, and
forethought, can stop the spread, or even
prevent the rise, of epidemics. Dr. Southwood
Smith says, "where certain conditions
exist, epidemics break out and
spread; where those conditions do not exist,
epidemics do not break out and spread; and
where those conditions did exist, but have
been removed, thereupon epidemics cease to
break out and spread." Overcrowding, the
accumulation of filth in and about all dwelling-
places, personal uncleanliness, improper
food and impure water, stagnant ditches,
foul drains, marsh lands, and the like, all
these and other conditions of the same class,
it is within the power of man to alter or
remove.

The epidemics of the tropics differ somewhat
from those of the temperate zones.
There, where vegetation is so rank, and
organic life so profuse—insects filling the
lower strata of the atmosphere to the height
of fifteen or twenty feet—epidemics are
more violent and sudden than with us. The
outbreak of cholera alluded to, in the Eighty-
sixth regiment, at Kurrachee, in eighteen
hundred and forty-six, was a striking instance
of the fierce velocity of tropical epidemics.
After a period of damp, hot, stagnant, and
oppressive weather—for days not a breath of