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have capacity for 15 days' supply. The same company is conspicuous
by its advance in work for improving the water supply of
its district in other respects.
Bacteriological examination by Dr. Koch's process of gelatineplate
culture, was formerly conducted by Dr. Percy Frankland,
from which it appeared that, in 1887, the average reduction in
the number of micro-organisms present in the unfiltered water of
the Thames, effected before delivery to the consumers, amounted
to 96.7 per cent. This examination came to an end when that
gentleman left London. The Water Examiner, in his report for
1888, made reference to the value of this test, by cultivation of
the bacteria present in potable water, and to the desirability of
prosecuting further experiments. Opinions were expressed, that
it would be to the interest of the Water Companies, if the
efficiency of subsidence and filtration, in the purification of water
more or less polluted by sewage, could receive satisfactory experimental
demonstration: that the extension and increase of
population in the valleys of the rivers Thames and Lea tend to
increase the liability to pollution of the sources of supply, and
that it is very desirable that the Companies should be able to
show that their treatment of the water drawn from these sources,
is such as to obviate the dangers due to the introduction of
infected sewage into the rivers. Valuable results, he added,
would undoubtedly be obtained from experiments carried out on a
scale sufficiently large to represent fairly the conditions present
in actual work, and the expenditure necessary for the purpose
would be extremely trifling, compared with the interests at stake
in connection with the largest system of water distribution in the
world. The examination has since been resumed, and it appears from
Professor Frankland's report for May, in the present year, that
one cubic centimeter of each water, collected in sterilized vacuous
tubes, developed the following numbers of colonies of microbes:—
West Middlesex, 20; Grand Junction. 64; Chelsea 78. The
Lambeth Company's water developed 404.