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begun to decline before rain fell. In many districts, as those of the Nerbudda
valley, where the water-supply is largely derived from streams, an acceleration
of the decline is the only general effect apparent in the returns. In the districts,
of Raepore and Belaspore, where the water-supply is derived from tanks as well
as from streams, though the decline of the epidemic was at first accelerated, there
was subsequently in the end of July and August after continued rain an increase
in the number of villages attacked. In other districts there was little or no cho-
lera before the rains set in, but towards the end of July and in August there was
a marked rise in the number of places attacked. This course of events is most
evident in the returns from Nagpore, Wurdah, Bhundara, Chanda, and Sumbul-
pore.
266. It may be observed that in these districts the total number of villages
attacked was comparatively small, and the mortality, in proportion to the popu-
lation, slight; and that the disease was more confined to the larger towns, hav-
ing a wide area of polluted soil, and where the wells are liable to pollution
by percolation of sewage matters from imperfect drains through porous strata.
267. It may be said then that the general effect of rain on the prevalence
of cholera in these Provinces is undoubtedly salutary. Its salutary action is
more immediately evident in those tracts of country where the water-supply is
chiefly derived from streams and tanks ; in tracts of country where the water-
supply is derived from shallow wells, and where the soil and sub-strata are porous,
the first effect of rain is to cause an increase in the prevalence of cholera, but
when the several sources of water-supply have been fully replenished, cholera
everywhere subsides.
268. With regard to the character of the impurities in water that are con-
nected with the manifestation of cholera, the descriptions given of the water-sup-
ply of the towns and villages where cholera prevailed, indicate that the noxious
impurity is sewage or other decomposing animal organic matter. The villages
that suffered in the greatest degree were all dependent on sources of water-supply
more or less evidently liable to such kind of pollution. In the case of the larger
rivers, there can be no doubt that the water was polluted by such matter to a
terrible extent; and from what may be seen everywhere of the habits of the
natives, and their carelessness (particularly of the lower castes) in this respect,
there can be little doubt that the water of streams, tanks, and surface wells, is
very commonly polluted by sewage matters. There is, however, another mode by
which the sources of the water-supply of the people may become impregnated
with putrifying animal matter. The tanks, surface wells, and even deep wells,
that are uncovered and open to the air and light, all swarm more or less with
animal life; and in the hot weather, when evaporation is excessively rapid, and
the water in the several sources of supply is reduced to its lowest ebb, it is most
probable that a large proportion of the insects and animalculœ die and putrify.
This would be particularly likely to happen in those surface wells and springs,
where the quantity of water is so small that the mud at the bottom is disturbed
whenever water is drawn.
269. It is a common practice with the natives to preserve large fish and
turtles in their tanks, and sometimes even in their wells, under the belief that
they keep the water sweet. That the presence of fish in a tank keeps down the
excessive increase of the lower forms of animal life, and in this way tends to pre-
serve the purity of the water, is not unlikely; but it is probable that in the very hot
weather, and especially in seasons of drought, the destruction of insect life may
be more general than can be counteracted by such means, and that even the death
of the fish themselves may add to the impurity of the water. If there were any
connection between the use of water rendered impure by such means, and the
prevalence of cholera, we should expect to find that the disease would prevail