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superintendence give continuously good results tlie strict insistence of bacteriological
examination can be restricted to times of danger, i.e., times when the consumption of water
is greatest, periods of frost or danger of epidemics. In the meanwhile an examination every
three days of the totally filtered water would be sufficient. (Bacteriological examination
as it now takes place—when it does take place—i.e., a weekly examination of the totally
filtered water, is in all circumstances to be looked upon as insufficient.) In those periods
when the bacteriological control is less strict there should be close and strict regulation of the
pace of filtration so as to have assurance that the process is properly carried out."*
Obviously the efficiency of the filtration effected by the several companies cannot be properly
appreciated by information as to average monthly rates of flow, but must be judged by the maximum rates
at any one time. Koch's standard would give approximately 49 gallons per superficial foot of filter per 24
hours, or about two gallons per hour. This standard was, as shown by the water examiner's table,
exceeded by the Grand Junction, the Lambeth, the New River and the Southwark and Vauxhall Companies.
Dr. Frankland strongly recommends double filtration "as affording a second line of defence
against the invasion of pathogenic microbes." "Experience," he says, "teaches that even the best arranged
filtration plant may at times pass an objectionable number of microbes. A second filtration would, if not
invariably, at all events when the filters are recently made or are not working satisfactorily, be very
desirable, so as to keep down the number of microbes per cubic centimetre to a very moderate limit.
That double filtration is not an impracticable project is proved by the fact that the Grand Junction
Company have already begun to carry it out on a very considerable scale. Of course gravel water would
not need double filtration."
During 1891 and 1892 an investigation has been made by Dr. Alfred Ashby, Mr. G. H. Fosbroke,
and Dr. George Turner, on behalf of the Council, of the watersheds of the Thames and Lee with a view
to enabling an estimate to be formed of the risks to these rivers and their tributaries, as public water
supplies, from pollution of every kind, and as to the probability of the pollution increasing or decreasing.
The results of these investigations were submitted to the Royal Commission on Metropolitan Water
Supply.
Constant supply.—The Metropolis Water Act, 1871, empowers the Metropolitan Board of
Works (London County Council) to make application to the several water companies for a constant
supply of water in any district in London other than the City. As the result of the action of the
Council and of the water companies, the number of houses in London receiving such supply was
increased during the year to about 69 per cent, of the houses in London.
The London Building Law.
The requirements of the London building law as to open space about buildings are included in
two Acts. The Metropolitan Building Act, 1855, section 29, provides that every building used or
intended to be used as a dwelling house, unless all the rooms can be lighted and ventilated from a street
or alley adjoining, shall have in the rear or on the side thereof an open space exclusively belonging
thereto of the extent at least of one hundred square feet. The Metropolis Management and Building
Acts (Amendment) Act, 1882, section 14, requires every new building intended to be used wholly or in
part as a dwelling house, and erected on a site not previously occupied in whole or in part, to have
directly attached to it and in the rear of it an open space exclusively belonging to it which varies in
proportion to the frontage. If the frontage be 15 feet or less, the open space must be 150 square feet;
if exceeding 15 feet, but not exceeding 20 feet, 200 square feet at least; if exceeding 20 feet, and not
exceeding 30 feet, 300 square feet at least; and if the frontage exceed 30 feet, the open space must be
300 square feet at least. Thus between two parallel rows of houses backing on each other there must be
an interval of some 20 feet or a little more irrespective of the height of the buildings, and this open
space subject to the requirement of 100 square feet of open space mentioned above may be covered with
buildings to the level of the height of the ceiling of the ground floor storey. Numerous urban
authorities in England either by local Act or by by-law made under the Public Health Act, 1875, require
open space in proportion to the height of the building, and there is urgent need of this requirement in
London.
In many instances buildings have been erected which overshadow others, depriving them of the air
and light necessary to make them healthy habitations. The only provisions in the London building law
for limiting the height of buildings in proportion to the width of the street are contained in section 85 of
the Metropolis Local Management Act, 1862. This section prohibits the erection on the side of a new
street, of a less width than fifty feet, of any building, except a church or chapel, which shall exceed in
height the distance from the external wall in front of such building to the opposite side of such
street.
The London County Council (General Powers) Act, 1890, prohibits the erection, without the
consent of the County Council, of any building, except a church or chapel, of a greater height than
ninety feet, exclusive of two storeys in the roof and of ornamental towers, turrets, or other architectural
features or decorations.
Upon the proper ventilation of and the admission of solar rays into streets the healthiness of a
city greatly depends, and the existing law is insufficient for ensuring these conditions. On the 21st
of December, if the houses be 40 feet high, to secure one hour of such sunlight on houses situated on a
meridional street in the latitude of London, the width of the street would have to be 19'81 feet,
for two hours 41'83 feet, for three hours 69'14, and for four hours 107 39. So again if the street
* "Water Filtration and Cholera," by Professor R. Koch, of Berlin. Translated from the German by Albert
J. A. Ball, Esq., B.A., of the Local Government Board.