?110	Extent and course of the plague	[ CHAP. V.
the remainder spread over twenty-two of the thirty-two quarters into
which the city is divided. The actual number of cases which occur-
red during the week was, it is known, much greater than the number
reported. Bearing in mind the slow rate at which the infection of
plague spreads during the early period of an epidemic, it is certain
that the disease must have been in existence for a considerable time
before the cases could have become so numerous and so widely
diffused.
Cause of the
outbreak.
The immediate cause of the outbreak must remain a matter of con-
jecture. It would seem probable that the infection was introduced
by sea, since it is most unlikely that the disease could have been
carried overland from the small endemic centre in the Himalayas,
or that it could have been introduced from beyond the border by any
land route. It has been seen that an endemic plague centre exists
on either side of the Indian Peninsula-to the west in Mesopo-
tamia and to the east in China. In so far as is known, there was no
unusual prevalence of plague in Mesopotamia at the time of the out-
break in Bombay. But on the west the second or 1896 outbreak in
Hong-kong had not died out when Bombay became infected. The
probability would therefore seem to point to China rather than to
Mesopotamia as the source whence the infection was derived. In
connection with this question it is interesting to note that Staff
Surgeon Wilm, whilst eulogising the general arrangements made
in Hong-kong to stamp out the epidemic, remarked that too little
attention was paid to the water-borne traffic. And in India
quarantine was not imposed against Hong-kong during the 1896
epidemic at that place, although it was imposed during the more
important epidemic of 1894 and withdrawn when that epidemic
ceased. Intimation of the recrudescence in 1896 was not sent to the
Government of India, and it would appear that in Egypt also quaran-
tine was not imposed. It is therefore quite possible that undetected
cases of plague may have arrived from Hong-kong.
Abnormal
climatic condi-
tions.
The outbreak of plague in Bombay occurred at a time of unusual
climatic conditions. The early cessation of the monsoon of 1896 is
notorious in connection with the widespread famine which resulted
in India. Dr. Weir has given the following account of the pheno-
menon as it affected the City of Bombay:-
" The mean annual temperature of the year was 80·7, the second
highest on record in the last 51 years. The total fall of rain amounted
to 87.6 inches, being 15 inches above the average. But the distri-
bution of the rainfall was abnormal, for, instead of being distributed
over four months, it was distributed over a much shorter period-a