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EPIDEMIC CHOLERA OF INDIA OF 1875 AND 1876.

[Section IV.

   The following is the memorandum:—

   "We are anxiously looking out, expecting the advance of epidemic cholera over Northern
India a few weeks hence, and newspaper reports tell us that already in the Bombay Presidency
cholera is epidemic along a line reaching from the northern to the southern, limits—from
Neemuch to Belgaum.

   "I regard this cholera of Western India of the spring of 1872 as the cholera of a new
invading epidemic, and I look upon the individual manifestations in the different districts,
appearing between the end of last year and the present date, as reproductions of a cholera
actually distributed over Western India in the last months of 1871. Hence I regard the
trifling manifestations that may have occurred between the 20th October and the end of 1871,
likely to prove of extreme value in determining the epidemic relations of the cholera now
manifest.

   "This opinion is based not only on the epidemic occurrences now in progress in the
Bombay Presidency. We are tracing with care the events of the end of 1871 in the Bengal
Presidency also; and to me investigating the facts in the light of parallel history, the manifes-
tations both in the east and west present themselves as portions of one and the same epidemic.

   "When the history of this epidemic comes to be written and the successive stages of its
progress recorded, my impression is, that we shall be called on to say at what date this cholera
reached the Bombay Presidency from the east.

   Regarding the epidemic of 1868, of which the present epidemic is the successor, the
Sanitary Commissioner for Bombay stated simply, that he could not tell whence it came nor
how it originated; this was the epidemic which is shown on our map of 1868 geographically con-
tinuous with the cholera of the same year in the valley of the Ganges. But the history of
1871-72 takes us back to a different parallel. The great western cholera of the end of
1859 appeared in succession to the great Gangetic cholera of the spring and autumn, while
in the intermediate area, namely, the Central Provinces, cholera did not manifest its presence
before the spring of 1860. This was the area which I could not map out as covered by
invading cholera in 1859, because I found no record of invasion after patient investigation.
The epidemic facts of 1871 show the value of the caution which I exercised in declining to
commit myself in the matter as regards 1859. To go further back still, the western epidemic of
1853-54 also exhibited an epidemic phenomenon precisely parallel. This dreadful cholera, which
occupied the valley of the Ganges and the eastern division of the epidemic area generally as
far west as Cawnpore, where the 70th Regiment lost 183 men, was lost to us in Northern India,
and leaving the Central Provinces almost untouched, although the indices were distinct, reached
Bombay in October.

   "The point I wish to make clear is this, that a great Gangetic cholera may invade Bombay
towards the end of an epidemic year, while in the intermediate tract cholera may not have been
visibly distributed, or in which its presence may have been marked by the merest sprinkling of
what are called sporadic cases. Theoretically, I ascribe the phenomenon to the distribution
of the material of a new epidemic over Western India after the setting-in of the north-east
monsoon, and to its precipitation over a wide stretch of country adapted for its revitalisation
in the spring. Reproduction as the rule is earliest in Nimar, and in April Malwa and Guzerat
show the cholera when reproduced.

   "The question then is, at what date this cholera apparently passing over the Central Pro-
vinces without leaving its impress, entered the Bombay Presidency."

   In my report on the cholera of 1872 I have taken up the same subject at length.

The significance of the spring
cholera of 1818 of Western India
reviewed after the experience of 1872
and 1875.

   From this note, written five years ago, this may be gathered, first, that I regarded Jameson
as describing erroneously the method in which Western India
was entered in 1818, when he spoke of streams of cholera
diverging from Banda and Saugor in March and April; and
secondly, that I had serious doubts of the correctness of my con-
clusion that cholera was aërially distributed over Western India in the spring of 1818.

   What had been impressed on my mind by further experience was, that the re-vitalisa-
tion of cholera is, as regards the date of re-appearance, a phenomenon subject to little varia-
tion, while the distribution of a spring cholera is much subordinated to meteorological contin-
gencies. I had studied these dates in relation to 1858, 1862, and 1867, known years of
re-vitalised cholera, and recorded them for future use in determining at what dates a cholera
sown over a province shall again come into manifest existence. These dates, so beautifully
consistent throughout sixty years, I should do wrong not to recognise as fixed and natural, not
for an invading cholera, but for a cholera asserting by local re-vitalisation the fact of its previ-
ous presence. They are subject to fluctuation with no minor contingency, and a hundred years
hence the tabulated statements will exhibit identically the same facies.

   And that the original distribution may occur with little manifestation in the human being,
or none at all,. to show the fact that a province has been covered, I have made evident by the
analysis of the cholera of November and December, already noticed, giving warning of the in-
vasion of Northern India and foretelling revitalisation at the due date. I call attention to
this memorandum that it may be consulted if the evidence be sought for.*

   Before the repeated experience of late years had brought the fact so clearly to light, the
impression that some such explanation of phenomena apparently exceptional would be found was
present to my mind. Under this impression I wrote the words in my original report (page
87): " For epidemic manifestation to be obvious to us, it is necessary that it should take place
coincidently with the vitalisation of cholera, and therefore at the seasons when cholera naturally

*See also Postscript, page 317.