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4.—If Dr. Hamer's explanation of the outbreaks in Southwark and Lambeth be correct it must
obviously meet certain requirements. It necessitates that all the persons included in the special
outbreak shall have eaten fried fish from a particular vendor at a time when they must have received
infection, and it must be accepted that this requirement is substantially complied with. To those
familiar with the difficulties attending such an inquiry it will be admitted that the cases concerning
which Dr. Hamer speaks with less certainty on this point are exceedingly small in number. There
are, indeed, only six cases in Southwark, among those in the special outbreak, which Dr. Hamer does
not feel justified in definitely including among the consumers of fried fish from the particular vendor,
at a time corresponding with the probable date of infection. Two of these may have done so, but the
fact could not be ascertained from themselves. Of the remaining four, all were consumers of one fish
or another from this vendor, who had two shops practically adjoining each other, one in which he
sold wet fish, shell fish, &c., the other restricted to the sale of fried fish. Of these four, two may
possibly have eaten fried fish purchased from this vendor.
5.—Dr. Hamer found that if he took a particular fried fish shop in Southwark for a centre and
drew a circle of a quarter of a mile radius round it, he practically covered the ground in which the
exceptional incidence of enteric fever was manifested in this locality. The cases of disease were found
to be more thickly distributed near the centre than further away.
In order to test the proportion of persons eating fried fish from this particular shop, two areas
within the circle were taken for the purposes of detailed inquiry, and it was found that in these areas
42 per cent, of a total of 900 persons had eaten fried fish from this particular shop at a time when
the Southwark population became infected. If we were to assume that these proportions obtained
throughout the whole circle, which includes a population of about 25,000 persons, the incidence of
disease upon the two classes of population, viz., those who purchased at this shop and those who did not,
would be as shown in the following table. I have taken the facts relating to September for the statement
of these proportions, so as to ensure inclusion of all cases possibly concerned with this cause.

* Exclusive of two cases concerning which there is doubt as to whether fried fish was eaten, and inolusive of four cases
concerning which it was ascertained that fish but not that fried fish was eaten.
6.—It is however probable that this division of population into two classes on the basis obtained
by inquiry in two areas, both of which it should be stated are situated between about 100 and 200 yards
from the centre, may not represent the actual proportions in the whole circle.† In areas nearer the
centre the proportion of persons dealing at this fried fish shop would, caeteris paribus, be greater, in
areas more remote would be smaller. The matter may be further tested by limiting consideration to
the population resident in a ring between 110 and 220 yards from the centre in which these areas are
situated. The figures then obtained are as follows —

† If we adopt the minimum percentage given by Dr. Hamer on page 12, namely, 25 per cent. instead of 42 per cent., the two populations
would then be, respectively, 6,250 and 18,750.
‡ Exclusive of one case concerning which there is doubt as to whether fried fish was eaten and inclusive of one case
concerning which it was ascertained that fish but not that fried fish was eaten.