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242
for dietetic purposes; maintaining that in the interests of
temperance and public health, it should, as soon as possible, be
substituted for that portion of the Metropolitan supply which is drawn
from polluted rivers. This "pure spring water," he said," is everywhere
abundant in the Thames basin; in dry seasons it constitutes
the sole supply of the Thames and the Lea, and even after the most
protracted drought, more than 350,000,000 gallons of it daily flow over
the weir at Teddington, whilst a further very large volume of it joins
the Thames lower down." He considered that it would be a valuable
boon to London if even a small fraction of this prodigal supply could
be collected, preserved from irremediable pollution, and distributed to
those portions of the Metropolis which are not at present supplied with
such water. The principal objection to the water is its hardness, but
this is an objection easily surmounted.
It was stated in a former report that several of the Companies are now
impressed with the necessity of ultimately abandoning the rivers
Thames and Lea as sources of water-supply, and some of them have
already completed works for utilizing underground waters which have
undergone natural filtration through great thicknesses of gravel and
sand, whilst others are sinking deep-wells in the chalk. In 1884 it
had to be remarked that the protection provided by the common law
to rivers was denied to subterranean sources of water, which, it
appeared, as the result of a decision by Mr. Justice Pearson in an
important ease (Ballard v. 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.
The year 1887 was characterised by a remarkably small rainfall, never the
less London was abundantly supplied with water. The Thames was
unusually free from floods, and consequently the conditions were
particularly favourable for yielding a supply of water, containing
but little impurity either in solution or suspension. With the exception
of two samples collected from the mains in January, when the
river was in flood, all the filtered river water was clear and bright,
pointing to the care and efficiency with which the water is treated by
the Companies previous to delivery.
The temperature of the river waters varies greatly according to season
whilst that of the deep well water is practically constant throughout
the year. The variation in Thames water was from 38°3 Fahr. in
January to 68°4 in July, a range of 30°1; whilst that of the Kent Company's
water was only 2°0; from 54°3 in November to 56°3 in July.