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170
Tomlinson), might be polluted or poisoned to an unlimited extent
without legal redress. Happily, in the interests of public health, this
judgment was afterwards unanimously reversed in the Court of Appeal.
A marked and undeniable advantage of spring water is its uniformity of temperature.
The mean temperature of the Companies' waters is practically
identical, but the fluctuations in temperature, according to the season of
she year, are much more marked in river than in deep-well water. The
latter remains refreshing and palatable in summer, whilst on the other
hand, the risk of frozen pipes is greatly diminished in winter The range
of temperature in the water of the Thames, as delivered by five of the
Companies last year, amounted to 32°.4 Fahr., viz., from 36°.0 in March
to 68°.4 in July. The deep-well water furnished by the Kent Company
varied in temperature from 52°.9 in December to 56°.3 in July, a range
of 3°.4 only.
The past year," Dr. Frankland states. "has been particularly favourable for
studying the resources of the Metropolitan Water Supply. For, owing
to the exceedingly variable nature of the weather experienced, the quality
of the water in the rivers suffered far greater fluctuations than
during the two previous years, in which the meteorological conditions
were in many respects exceptional. For the past year, however, the
rainfall was considerably above the average during the months of
January, May, and December, whilst in the remaining months it was
almost invariably below; thus, during no less than a fourth part of the
year, the conditions were unfavourable to the purity of the river supply.
Notwithstanding the prevalence of these unfavourable conditions during
such a considerable fraction of the year, it is especially noteworthy that
every sample of water collected from the mains in the Metropolis and
submitted to examination, was clear, bright, and free from turbidity.
. . . The high efficiency of treatment and consequent general
improvement in the quality of the river portion of the Metropolitan
water supply, which has been conspicuous for several years past, has
therefore been more than maintained during the year 1886."
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 show that whilst the unfiltered Thames water exhibited,
by gelatine cultivation, on an average. 2,219 germs per cubic centimetre,
the filtered water contained only 38. which corresponds to a reduction
of 98.3 per cent.
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
none of the waters being turbid on any occasion.