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The Special Purposes and Sanitary Committee of the Board made a report on the subject
(12th January, 1886), of which I have no copy, but certain recommendations contained therein,
already referred to as having been approved by Sir Henry Roscoe, are set out in a "Report
upon the Question of Sewer Ventilation," by the late Vestry's surveyor (24th September, 1889).
Among the opinions expressed, and the remedies suggested, in the summary report (5),
adverted to, the following may be cited.
(a) "The only effective mode of preventing the escape of foul gases from sewers is the rapid
removal and deodorisation of the sewage by copious dilutions with water."—(Engineer, Metropolitan
Board of Worts, 1856.) (b) "By ventilating shafts in the trunk sewers for the purpose of drawing the
foul gases away from the branch sewers"; and "By erecting shafts with large fireplaces so constructed
as to consume the deleterious gases before they pass up the chimney."—(Br. Lantester, Medical Officer
of Health, St. James's, Westminster, 1857.) (c) Before a Committee of the House of Commons appointed
(in 1858) to enquire into the state of the Thames, ventilation of sewers by means of furnaces and shafts
was suggested. This system, "possibly efficacious for a particular and limited area," could not be "utilised
to the wide range of the Metropolis.'' Mr. Haywood, engineer to the City Commission of Sewers, spoke
of the "exceeding difficulty in doing it at all," but if it could be done, it would only be "at an enormous
expense." Ventilation by furnaces was described by him as being "impracticable"; for the air would be
drawn only from the inlets nearest to the furnaces, (d) On a proposal to " ventilate by means of a water
fan "(suggested by Mr. White, M.R.C.S., 1860), the engineer reported that this plan had been "sufficiently
considered to enable him to state that an attempt to carry it out would prove a failure," and, in any
case, any good effect would not be perceptible beyond the first inlet to the sewer through which air could
enter the shaft, (e) Large lamps to serve as ventilating shafts were recommended in 1860. (f) Charcoal
trays were extensively employed in 1866 to mitigate stenches; and proved effectual for the purpose by
occluding the ventilating gratings, (g) The efficacy of water. for diluting the sewage, was again emphasised
in 1866; but the remedy was said to be too costly— the water companies, moreover, not being
willing (or able) to supply the requisite quantity— and also the efficacy of pipes carried to the tops of
buildings : but it was stated that householders objected to the practice for fear of injury to health—an
objection which carries less weight now. (h) In 1869 the engineer referred to ventilation by means of air
flues connected with the furnaces and shafts of factories and other buildings; "the current of air
through the pipes appears to be constant, having the same appreciable effect in the sewer as an ordinary
ventilating shaft." (i) A committee of the Metropolitan Board in 1872, after four years of investigation,
reported that " no one plan of ventilation, however well adapted to succeed locally, would be
applicable to the whole of the Metropolis." Reference is made in certain of the reports to the utility
of intercepting valves (described indifferently as flaps, screens, shutters) in branch sewers connected with
main sewers, to prevent the noxious gases passing from the main sewer into the branch sewers: this
treatment is said to be more efficacious where combined with the erection of ventilators at the upper
(dead) ends of pipe sewers.
Reference has already been made to the views of Sir Henry Roscoe, who prepared a number
of reports—all of which were summarised in my annual reports for 1887-1889—dealing with
"The Deodorisation of Sewage in the Metropolitan Sewers," and "The Deodorisation of Sewage
at the Outfalls"; the latter being a subject of pressing importance at the time, owing to the state of
the River Thames. With regard to the use of chemicals for disinfecting the emanations from
the Board's sewers, it appeared that a mixture of manganate of soda and sulphuric acid had been
employed, at a cost, in 1866, of £40,000, with but little advantage. Sir Henry Roscoe did not
favour a large expenditure for this purpose, but expressed the opinion that if it were determined
to disinfect the sewers at all, bleaching powder and sulphurous acid would be cheaper, and as
efficacious. But he was of opinion that "the most effective method of accomplishing the deodorisation
of the offensive emanations was, whenever practicable, to dilute them with fresh air by
means of suitable ventilation."
The history would not be complete without a reference to the reports on the subject, presented
to the Kensington Sanitary Authority by their late surveyor—3rd March, 1885, 24th September,
1889, and 18th October, 1897. Mr. Weaver favoured the use of pipes carried up houses,
if sufficiently numerous, in addition to a sufficiency of gratings at street level, and exhaust ventilating
pipes from the dead ends of sewers. Flushing, however, was the remedy he most
affected; were not the cost of water prohibitive, and supposing the requisite quantity forthcoming.
He would also flush "dead ends" by means of automatic flushing tanks, with inner cisterns
constantly discharging disinfectants into the flush-water. The latest expression of this gentleman's
views is contained in a report to the Works Committee (July, 1904), in which it is stated that,
"with an intimate acquaintance with all the known methods of sewer ventilation, natural, mechanical,
and chemical," he had "nothing to add or alter" in the report of 1897." "As an outcome of
that report, 167 pipe-shafts had been fixed in different places by order of the Council up to