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be delivered during such periods, while keeping the intakes
closed. The position of the several Companies varies in this
respect very considerably. The following statement shews the
number of days' supply, represented by the capacity of the
reservoirs for unfiltered water, belonging to each of the local
Companies:—Chelsea, 14*7; West Middlesex, 7*6; Grand
Junction, 3"7. But the Grand Junction Company's resource,
during floods, of pumping from the gravel beds adjoining the
Thames, is practically equivalent to an addition to their provision
of storage reservoirs. For sake of comparison it may
be added that the East London Company 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.
Dr. Percy Frankland's biological experiments by the
process known as gelatine-plate cultivation, 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 percent.
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 shew 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