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120
Southwark, Grand Junction, and Lambeth Companies; the New River
Company's water often rivalling the deep well waters in respect of
organic purity."
The importance of the freedom from bacteria of any water supply
is so great that I have pleasure in quoting Professor Frankland's remarks
on this subject, and in giving the results of his examination of the New
River Company's supply.
BACTERIOSCOPIC EXAMINATION.
It has been proved by an overwhelming amount of evidence that Cholera and Typhoid
Fever, are, the first generally, and the second frequently, propagated through the agency
of water. The fact that Cholera generally travels up stream in tidal rivers is only
apparently inconsistant with this statement. The disease almost always arrives at the
mouths of rivers by sea. The choleraic dejections are thrown into the river and are carried
by water up stream as far as the tide reaches; but there are few tidal rivers which are not
navigable by barges far above the range of the tide. The bargemen almost always dip
their drinking water out of the river, even in the tidal reaches, and consume it without any
filtration. They thus become infected, and convey the zymotic poison up stream as far as
the river is navigable, and, it may be still further by means of canals. The use of raw or
imperfectly filtered water for dietetic purposes from such sources is, therefore, in times of
epidemic especially, fraught with extreme danger. Fortunately, however, recent bacteriological
research, together with experience bought through the sacrifice of thousands of
lives, has demonstrated, in Hamburg and Altona, that efficient sand Alteration is practically,
a perfect safeguard against the introduction of the cholera bacillus into drinking water,
and it can scarcely be doubted that what is true of the cholera bacillus is also true of the
typhoid bacillus, although in the latter case there has been no such rigorous demonstration.
To attain this desirable result, however, it has been no less convincingly shown that the
filtration must be efficient, for the experience, gained so dearly in the great cholera
epidemics in London, has been strikingly confirmed by Dr. Koch's exhaustive investigation
of the cholera epidemics at Altona and the Nietleben Lunatic Asylum in Germany.
The bacterioscopic examination of the water supplied to vast communities like London
has therefore become an investigation of the highest importance from a hygienic point of
view, and I am, therefore, each year devoting an increased amount of attention to the
bacteriological character of the various waters supplied to the metropolis.
The samples of water submitted to this examination were obtained at the works of the
respective Companies immediately after the water left the filters, and before it was pumped
into the distributing mains. By this method of sampling, the maximum degree of sterility
of each water is determined. This utmost freedom from microbes, after all sources of
contamination have been passed, is obviously the most important moment in the history of
the water; for the smaller the number of microbes found in a given volume at that moment,
the less is the probability of pathogenic organisms being present; and, although the nonpathogenic
may, and probably will, afterwards multiply indefinitely, this is of no consequence
in the initial absence of the pathogenic. In this determination of maximum
sterility, it is of course of the utmost importance that multiplication should be prevented