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drains are properly constructed, any sewer air passing into the house drain can only
escape through a ventilating shaft.
So far as properly constructed drains are concerned, there does not appear,
therefore, any reason for the introduction of the interceptors, but I must point out that
its abolition must of necessity render the defective drain a more imminent source of
danger to the household.
Part 3 and Part 4 are mainly scientific, and deal with the chemistry and
bacteriology of the sewer air. Epidemiologically, sewer air is shown to be harmless,
and the only argument against it is that the smell is occasionally offensive, and that
persons susceptible to smells are, or might be, affected thereby.
In short, it is argued that if sewer air did get into the house, little harm would be
occasioned.
The conclusion arrived at in Part 5, "Bacteriology of Drain Air," shows that
graver dangers are to be feared from the air of the house drain than from the air of the
sewer.
The general evidence obtained by the investigation is given in Part 6, and in
arguing that the breathing of sewer air does not necessarily result in illness, the case of
the sewer men is cited. There does not appear to be any definite evidence that these
men suffer from either general ill-health or from such diseases as enteric fever or those
diseases designated " Septic."
Some experiments conducted on animals showed that guinea-pigs which breathed
nothing but sewer air are no less healthy than those kept in less unpleasant
surroundings.
Part 7 is confined to ventilation of the sewers, and perusal of this part of the
Report leads one to the conclusion that the importance of sewer ventilation has been
largely exaggerated. It appears, however, that if ventilators are necessary, the higher
up the openings are placed the better will they carry away the offensive smells.
From the above it will be seen that the case against the intercepting trap appears
to be supported by an overwhelming volume of evidence, yet in the conclusions
contained in Part 8, the Commissioners, having regard to the varying susceptibility of
different persons, and feeling that the matter is one of serious public health importance,
have decided that the question as to whether the intercepting trap is required or not is
one that should be considered by the Local Authority, the merits of each case and the
peculiarities of each locality taking their due and proper place in their deliberations.
REMOVAL OF FISH OFFAL.
The contract with Messrs. F. S. Hempleman and Co., for the removal of fish offal,
expired on the 21st May, 1912, and on the recommendation of the City Engineer and
your Medical Officer of Health, was renewed for a further period of 12 months.