PRESIDENCY GENERAL HOSPITAL.

53

1871.

       To criticise all the results as demonstrated in these detailed statements would be
premature. A longer series of observation is needed. Their form I propose to maintain in
future with such modification as may from time to time appear to be indicated for examin-
ation and report. There is however one point to which I beg again to draw attention,
viz. the diminution in the number of cholera cases of late years:—

Diminution of cho-
  lera.

        I believe down to 1868 great laxity prevailed as regards the water-supply of the
mercantile marine of this city; that it was mainly derived from the river between Matia Brooj
and Chitpore, at which points the night-soil of the suburbs and city respectively were cast
into the Hooghly; that about this time, owing to representations in the public prints and
to Government, though no Change had been made in the disposal of the city and suburban
sewage, greater care had been enforced in the supply of filtered water; that in 1870 laxity
again crept in, and there was a consequent increment of the scourge, until thorough
supervision of the water-supply to the shipping was again enforced, and measures
were taken to prohibit the defilement of the Hooghly with sewage and to supply the
shipping population with municipal water. The full effect of these sanitary measures has
been witnessed in 1871, when the whole of the marine community was provided with the
purified and filtered water of the Corporation. Doubtless, impure water, or water charged
with the cholera poison, is one of the chief means by which this scourge is communicated to
man, especially in its endemic form. But it may also be conveyed into the digestive canal
in ordinary articles of food, and in its epidemic form it is undoubtedly often spread
through the medium of the atmosphere. It is not difficult, if these propositions are received,
to understand why improved conservancy and improved water-supply should culminate in
diminishing the frequency of the disease. If therefore the decrement of 1871 be maintained
or still further developed in future years, Snow's theory of the chief mode by which cholera
is spread through contaminated water-supply will have received irrefragable support, and
the path will have been indicated for the suppression and eventual comparative extinction of
the malady in the other cholera fields in the delta of the Ganges. If, I repeat, Snow's
doctrine be still further confirmed by the results of the Calcutta drainage system and water-
supply as time rolls on, the system of preserving in a state of purity the drinking water of the

Causes.

Water-supply

Importance of
  water conser-
  vancy

O