one house and leave another. But it has been generally found that
the attacked house or village held out special invitation from its
insanitary condition. The same houses or the same localities will be
revisited in recurring epidemics, because the conditions remain the
same; remove those conditions, and at the next recurrence the locality
will escape. At Malta it was found that the same localities and houses
which yielded the majority of plague deaths there in 1813 yielded the
majority of the deaths in the cholera epidemics of 1839 and 1867, and
that in the intervals the same localities yielded the majority of cases
of small-pox, fever, and of an anthrax, a very special eruptive epidemic
attended by carbuncles. Hence, while we are unable either to account
for the cause or to prevent the periodic recurrence of epidemics, the
sanitarian has learnt that it is possible to mitigate the severity of
the visit; and that, whether these evils arise from the occult causes
to which I have alluded, or from other causes, pure air and pure
water afford almost absolute safeguards against most forms of zymotic
diseases.

In speaking of the pure-water question, he remarked: Although there are
many theories as to how far water which has once been contaminated by
sewage may again after a time become fit to drink, I am disposed to
think that there has never been a well-proved case of an outbreak of
disease resulting from the use of drinking water where the chemist would
not unhesitatingly on analysis have condemned the water as an impure
source; and it appears probable that, whatever may be the actual causes
of certain diseases--i.e., whether germs or chemical poisons, the
_materies morbi_ which finds its way into the river at the sewage
outfall is destroyed, together with the organic impurity, after a
certain length of flow. He pressed that there should be no further delay
in bringing the Act for the Prevention of Pollution of Rivers into