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a week but "all who were exposed at some time or other during the week to the risk of catching
diphtheria at school." He thus takes for his populations attending the Board and National schools the
total number of children on the register less those absent during the entire week.
The children attending these schools, however, do not all live in the affected area; moreover,
some of these children are over 12 years of age. Thus these populations are somewhat overstated for
the purpose of applying cases of disease limited to the affected area. The effect of this on the rates of
attack for these two schools is not, as a matter of fact, of great importance* ; but, inasmuch as the
number of other children remaining in the population of the affected area is obtained by deducting
from the total number of children in this area the children attending the schools, every addition to the
estimate of school population leads to diminution of the estimate of the remaining child population,
and thus Dr. Smith arrives at an estimate of 67 where Dr. Hamer arrives at 300, and thus practically
multiplies Dr. Hamer's attack rate for this population by 4£, and makes it exceed the attack rates of
the school populations.
Now Dr. Hamer, in basing the school populations in the affected area on the average
attendance of a week, had included in this population those who lived outside the affected
area, and had thus amply compensated for any addition which might properly be made
in view of the circumstance urged by Dr. Smith. I have however, to put the matter beyond
doubt, had enquiries made by the Council's inspector, Mr. Jury, as to the number of children
who were resident in the affected area immediately after the summer holiday of last year, who were of the
ages 3-12, and who were not attending these schools. This inquiry was made at 575 houses situated in
thirty streets in the affected area, with the result that 267 such children were found. The houses
visited included those most likely to contain children not attending these schools; but it is a fair
assumption that the remaining 33 children would be found if the remaining 867 houses in the rest of
the area were visited. I have not thought it necessary to pursue the matter further, for I am satisfied
that Dr. Hamer's estimate of 300 understates rather than overstates the number of such children, t
Dr. Hamer's conclusion that there was much greater incidence of disease (first sufferers) upon
children attending the Board and National schools than on other children is, therefore, fully confirmed
by this inquiry.
With respect to No. 4, Dr. Smith does not contest Dr. Hamer's statement that there was special
incidence of attack (first sufferers), on certain classes in the Board and National schools, but again he
offers no explanation of this circumstance.
I now propose to refer to the additional points discussed by Dr. Smith in his report.
1. Dr. Smith's report contains the following statement—
"The progressive tendency of the cases to occur in groups will be seen at once. The
remarkable group of 14 cases, which includes 7 first attacks in families (subsequently
referred to as 'first attacks'), occurred during the summer holidays in 1896, and appears to
have escaped Dr. Hamer's notice, as his table shows only 5 first attacks as having occurred
between July 24th and August 24th. This is unfortunate, as a group of 14 cases, beginning
nearly a week after the closing of the schools, and all contained within the holidays, cannot
fail to be valuable in an enquiry into the relative amounts of school influence and non-school
influence, which go towards establishing an epidemic."
Dr. Smith has, no doubt, failed to identify the seven first attacks in households occurring during
the holidays in Dr. Hamer's chart, owing to the fact that Dr. Hamer's inquiry at the homes showed
that in two instances the first sufferer in the household was attacked before the beginning of the
holidays, that is to say, Dr. Hamer had obtained information of earlier invasion of these two households
than appears to have been known to Dr. Smith. These seven first attacks, therefore, are fully indicated
in Dr. Hamer's chart.
2. Dr. Smith sets out, in tabular form (table II.), and in order of date of notification, the
fourteen cases thus referred to, and proceeds to discuss the first five, the only ones (he says)
"occurring within a week of the closure of the school." He thus writes concerning them—
"These five cases are the only ones occurring within a week of the closure of the school.
Had infection been present in the school it is almost inconceivable that no case should have
occurred within the ordinary period of incubation (2 to 4 days), and that four cases should
occur almost simultaneously near the extreme limit (7 days) of the period of incubation.
Had these cases occurred from 5 to 7 days after the children returned to school, instead of
from 5 to 7 days after their holidays began, many would have considered it beyond dispute
that infection occurred 2, 3 or 4 days after the reassembling of the school, and the possibility
that infection might have occurred outside the school would have been summarily dismissed.
The inference in the case, as it actually happened, is that infection occurred 2, 3 or 4 days
after the children's last attendance at the school, and therefore indisputably outside the
schools."
Dr. Smith has fallen into error by not observing that the dates recorded in his table in
connection with these cases are dates of notification of the cases, and not dates of the beginning of the
illness; probably, in making this inference, he had before him his table A on page 14 of his report, in
which the first seven cases (which include the five under consideration) have incorrectly against them,
in the column headed "date of first symptoms," the date of notification, and he appears thus to have
thought of the dates of notification as being the dates of first symptoms.
*There were a few cases (first sufferers) anion? children attending the Lewisham-bridge school and living outside the "affected
area" who were attacked between September 1st and October 10th. These cases Dr. Hamer ha* not included among the cases upon which
he calculates his scho >1 attack rote, but be would obviously have to do so if he adopted Dr. Smith's larger school populations obtained
by inclusion of school children living outside the " affected area."
†Dr. Smith's discussion of this matter contains an error which it may be well to mention. He evidently confuses the
Industrial school with the Orphanage, as he refers to "150 inmate* of the Industrial school (attending the National schooi)." The 150
children in the Indus:rial school do not attend the National school, wherea^ the 100 children in the Orphanage do. When he makes
his subtraction from the child population in the affected area for the purpose of arriving at the number of children not attending
the Board or National schools, he include* among the National tchool children 100 children from the Orphanage, which is not situated
in the affected area, and makes no allowance for this fact.