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44
complained of was effectually removed, and no further illness has
been reported.
It is much to be wished that some effectual plan may be soon
discovered for ventilating sewers; and, although I do not profess
myself competent to decide what direction such a discovery is
likely to take, the most promising idea I have yet heard proposes
the extraction of foul air by the action of fans placed in suitable
localities, the present ventilators being retained in the capacity of
inlets for pure air, instead of outlets for foul air; acting, in fact,
like the down draught in a mine. We all know, by reading, what
great lengths of galleries in mines deep below the surface of the
earth are ventilated, and very efficiently, in this manner, and it
seems not unreasonable to hope that the system may be found
applicable to the purpose under consideration. Certainly, there
seems no reason to doubt the almost illimitable power of steam
fans to induce currents in any direction; and leaving the question
to be worked out by those who are making a practical study of it,
I can but wish them every success, believing an effectual system
of sewer ventilation to be one of the chief sanitary desiderata of the
present day.
WATER SUPPLY.
The Report, by Professor Frankland, on the analysis of the
waters supplied by the Metropolitan Water Companies during the
several months of the year, is, on the whole, somewhat more
favourable than usual. As regards " temperature," he notices the
wide variation in the waters derived from riverian sources, as compared
with the narrow range in the deep well water of the Kent
Company, derived from the chalk. The temperature of the Thames
water varied from 36° Fahr. in February to 68°.9 in June, a range
of 34°; while the range in the water of the Kent Company was
only 7°.9 Fahr., viz., from 51°.1 in May to 59° in September and
October. The total solid impurities—composed of a great variety
of substances, some of which are organic and very objectionable,
and at times eminently noxious, while others are either entirely or
comparatively harmless—was rather less than in previous years,
the progressive increase in the quantity which had been noticed
during the years 1871-2-3 having apparently ceased. The maximum
was observed in January, and the minimum in July. The
character of the Thames water, in respect of organic impurity
—as represented by its two most important constituents, carbon
and nitrogen—was practically the same as in the previous years.
The maximum pollution occurred in March, April, and December,
when the river was iu a very objectionable condition. In December
the Chelsea Company supplied this foul water in an unfiltered condition,
and contaminated with fcecal matter. The subjoined table
shows the maximum, minimum, and average quantity of organic
matter in the water, the amount of organic element (organic car-