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104
ideal source from which to derive the domestic water
supply of London. There are, however, two facts
worth remembering, which cannot be explained away.
The first is that no micro-organism known to be the
cause of disease has ever been found in the filtered
water drawn from the Thames ; and the second, that
there has been a steady diminution in water-borne
disease since efficiently filtered Thames water has
been substituted for the numerous wells and pumps
of former days. Hamburg has often been quoted as
an example of a city which, relying on sand filtration
of water from a polluted river for its supplies for
dietic purposes, suffered in consequence from a disastrous
epidemic of cholera. As a matter of fact
Hamburg itself was before the epidemic supplied
with practically unfiltered Elbe water, but Altona,
one of its suburbs, had efficiently filtered water from
the same river, taken lower down stream where the
water was more polluted. Hamburg had the epidemic
and Altona practically escaped.
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 131).
Infectious Disease.—During the year, 1,496 visits
of inquiry have been made with respect to infectious
diseases, 1,007 rooms have been disinfected, and 50