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hitherto adopted has been clearly shown, or whether non-ventilation
is fraught with the danger to public health which has been handed
down as a sanitary axiom.
There is no question that in unventilated sewers special precautions
have to be taken before entering for repairs, and also that
at times some sewer air does occasionally pass the trap at the sewer
end of the house drain, but if the house drain be ventilated, as it
should be in every case, the air would pass out of the ventilator at a
safe height above the roof—a much better situation for such discharge
than that of the street level—indeed, the high ventilating pipes of
the house drains on either side would appear to be the most natural
outlet for excess of gas in the sewer.
From the above considerations, 1 am disposed to deprecate any
lavish expenditure upon methods of artificially ventilating the sewers,
believing that they act when they are not wanted, and fail when they
are. I am of opinion (1) that, where practicable, as many shafts as
possible should be affixed to the dead ends of sewers and carried up to
a safe height—this has been carried out in the past successfully by
your Engineer; (2) that each offensive road grid should be dealt with
on its merits, the sewer carefully examined at the spot, and any
defect or condition calculated to cause deposit or impede the flow
rectified; (3) that, where no such defect be found, the grid be closed,
care being taken that the drains of all houses in the vicinity are
efficiently ventilated, not by openings at or near the ground level (the
so-called air-inlet), but by full-bore ventilating pipe carried above the
house from the highest part of the drain; (4) that the sewers be
efficiently flushed.
By efficient flushing I do not mean a spasmodic water-cart, but
periodical and daily flushing of the entire system during hot weather.
Experts cease not to tell us that there is a plentiful water supply for
London for many years to come, but the average Londoner has been
gradually educated into the belief that a plentiful supply means, not
that he may use plenty, but that if he is careful his supply will not be