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of inhabitants, are notoriously more favourable to the diffusion of disease than are the conditions 01
rural life.
" To the proposition lettered (d), it is replied that though the flood of August 13th must have
washed down such filth as was on the banks, that filth can only have been such as had accumulated
since the next preceding heavy flood, which was on July 1st, and that in this interval there had been no
traceable case of enteric fever in the area above the intake, and that consequently the filth cannot have
contained the specific poison which is essential for the production of enteric fever, and that the suggestion
that there may have been cases of fever unknown to the medical men above the intake is a perfectly
unsupported hypothesis.
" Dr. Barry, as we understand him, admits with some qualifications the truth of these criticisms,
but maintains that, when all due allowance has been made for them, there remains a body of evidence
which they are not weighty enough to counterbalance, and which, though it does not actually demonstrate,
constitutes a strong presumption that the explanation of the outbreak adopted by him was the
true one.
"We felt strongly that without very minute and accurate acquaintance with the locality, and
without much more elaborate knowledge of all the complicated circumstances of this and previous outbreaks
of fever in the Tees valley than it was practically possible for us to acquire, it was out of the
question that we should decide between these conflicting opinions.
" Although, therefore, we have printed the evidence put before us concerning this outbreak, and
have attempted to sum up as fairly as we could the main arguments on either side, we refrain from
expressing any judgment as to its origin. This much, however, we may say, that the pollution on a
given day of a river like the Tees, with a flow in time of flood of at least 1,000 million gallons in the
24 hours, by what must at most have been a very small amount of active enteric poison at a point 17
miles above the intake, should so seriously affect the water that the admission of a certain limited
amount of it into the reservoirs should produce, notwithstanding filtration, an extensive outbreak
lasting for some six weeks, is a hypothesis so startliug, and so entirely unsupported by previous
experience in other places, that it is fair to demand the most conclusive evidence before accepting as
proven ; and, though we attach great importance to the opinion of such an experienced inspector as
Dr. Barry, we cannot say that such conclusive evidence has in our opinion been brought before us."
On this subject I desire to offer the following observations—
Dr. Barry deals with an area containing ten registration districts. When enteric fever
prevalence, during two six-weeks periods, one at the end of 1890 and the other at the beginning of
1891, was considered as affecting each of these registration districts as a whole, it was found that excess
of this disease was limited to three, viz., Darlington, Stockton, and Middlesbrough.
The ten registration districts are divisable into 32 sanitary districts, and the special incidence
of the disease was manifested in only ten, nine of which are comprised in the Darlington, Stockton and
Middlesbrough registration districts, which are divisible into eleven sanitary districts, and the
remaining sanitary district was comprised in the Guisbrough registration district, which is divisible into
seven sanitary districts, of which it formed in respect to population less than one-tenth, and in which,
therefore, manifest excess of incidence was not shown when this registration district is taken as a whole.
Of the ten districts having excess of incidence, the excess was general throughout eight of the sanitary
districts which were urban, and affected only parts of the remaining two which were rural. The excess
of enteric fever was parallel to the distribution of the Tees water, selecting the three registration districts
specially supplied with Tees water out of a total of ten registration districts, the remaining seven not
being specially supplied; selecting ten sanitary districts specially supplied with Tees water out of
thirty-two, the remaining twenty-two not being specially supplied; affecting eight urban districts
generally, and two rural partially, and selecting out of these two rural districts only those parishes
specially supplied with Tees water.
With this striking parallelism between the special incidence of disease and distribution of Tees
water has to be considered the absence of any other condition parallel to this incidence.
Further, this special incidence was manifested on two occasions, both of which corresponded with
floods in the river Tees, and on the second occasion at a time of the year when, as Dr. Barry says,
enteric fever is unapt to be prevalent in this country.
Apart from the reference to dilution of impurities, to which I shall return presently, the
Commission in their report do not offer any reasons for not accepting Dr. Barry's conclusions other
than those put forward by Mr. Wilson, and I shall therefore limit myself to making a few observations
on the grounds which are indicated by the Commission as those on which Mr. Wilson relies as sufficient
to negative these conclusions.
1. As to Mr. Wilson's objection to proposition (a), Dr. Barry gives the death rates as well as
the attack rates, and it is found by examination of the death rates that these confirm the conclusions
based upon the attack rates.
2. As to Mr. Wilson's objections to proposition (b), Dr. Barry gives in his report the attack
rates for each of the thirty-two sanitary districts in the two six-weeks periods, and it is there seen that
with the exception of a very few districts where the figures were too small to give reliable rates, the
special incidence of the disease manifested itself in every district supplied with the Tees water, and
practically only in these districts. The disease was of course not spread uniformly throughout every
part of every district, and this is not matter for surprise when it is recollected that the virus is particulate
and is not dissolved in the water. Assuming Mr. Wilson is correct in asserting that places where
local insanitary conditions abounded suffered "exclusively or preferentially," this affords no explanation
of the special incidence of enteric fever during two periods of six weeks in numerous localities included
in a large area comprising ten registration districts.
3. As to Mr. Wilson's objection to proposition (c), this is met by comparing the rates of
incidence of the disease on urban districts supplied with Tees water and those otherwise supplied, and