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70
the theory and practice of filtration becoming better
understood.
A demand that the water-supply of the Metropolis
shall be beyond all chances of pollution rests on
something more than theory, but it is unfortunately
only too often necessary to reduce the demand for the
ideal to the limits of the practicable. The question is,
therefore, whether the existing supply, heretofore
found safe, and calculated to suffice for the needs of
the population for many years, should be abandoned in
favour of a new source from some distant part such as
Wales. The latter water may well be purer at its
source than the existing supply, but the chances of
dangerous pollution in transit would be enormous.
It seems more rational to extend the work of purifying
the river by compelling all riparian residents to
so deal with their waste products that no living
organism shall pass into the river, and to perfect the
system of filtration and storage. The control of the
water beyond the waterworks requires more attention
to eliminate the risks incurred in the mains and in
the house cisterns.
ADMINISTRATIVE WORK.
In so far as statistics can indicate the work
accomplished by the Department, the year's record
will be found in Table VI. in Appendix A (page 97).
Infectious Disease.—During the year, 1,124 visits
of inquiry have been made with respect to