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245
On one occasion the water of the Grand Junction Company was slightly
turbid; with this exception the supplies delivered by the Companies
in which we are interested were uniformly clear and transparent.
The Grand Junction Company's storage capacity is below that of some of
the other companies. This Company, however, have within the last
few years constructed very important works, by means of which much
of the water which they obtain is subjected to natural filtration in the
gravel beds adjoining the Thames, and it is doubtless in consequence
of this improved method of filtration that they have been enabled
generally to supply water of perfectly clear appearance even when the
river was in a very impure and flooded state.
The improvement effected in the river water by filtration, revealed by the
determinations of the relative numbers of micro.organic spores or
germs present in a given volume of the raw and filtered waters, is very
striking. These determinations are made by Dr. Percy Frankland,
and the results are very satisfactory.
When examined under the microscope, the sediment deposited by turbid
water, on standing, is generally found to contain living and moving
organisms. The occurrence of such organisms has become exceedingly
rare in late years, and last year, presumably, was altogether wanting.
The subjoined Table shows the annual averages of each determination and
thus summarizes the average results of the analysis of the waters supplied
by the local Companies during the year, the Kent Company's
water being taken as a standard for comparison.