Page 579

April 7, I 8 70]
NA TURE
admixture of human excretal refuse with their water, it
has long been maintained by the local authorities of many
parts of Lancashire that the evil was less in that district
than elsewhere, in consequence of the system adopted
there for dealing with such refuse not affording such
facility for its discharge into rivers as the water carriage
system. On this ground the introduction of the water
system of sewerage has been strenuously opposed. The
report of the Commission, however, dispels this illusion by
evidence which is conclusive in proving that the use of the
old form of closets with ash pits, earth closets, &c., affords
no protection to rivers. From a long series of analyses
of sewage from towns where such closets and middens
are used, it appears that, as compared with the sewage from
towns where water-closets are used, the composition of
both are remarkably similar. Besides the nuisance and
other inconveniences of the dry closet system, it appears
that the pollution of rivers is but very slightly prevented by
it. On the other hand, while the advantage gained by that
system consists merely in the retention of a small propor-
tion of the excreta in a state to be available for agriculture,
the treatment to which that portion is subjected renders
its value as manure very small. Moreover, this is usually
effected only at the expense of great risk to public
health, and at a cost which is - on the average double the
money return obtained. The Commissioners, therefore,
come to the conclusion that the retention of solid excreta
in middens is not attended with any considerable dimi-
nution in the strength of the sewage, though the volume
is somewhat reduced. On that ground they consider it
hopeless to anticipate any substantial reduction of sewage
pollution of rivers by dealing only with the solid residue
of excreta. At the same time they point out the fact that
the discharge of excretal refuse into rivers is not a neces-
sary part of the water-closet system.
  As to the influence of the dry closet system on health,
the Commissioners refer to the returns of the Registrar-
Gmneral, and to other evidence, as showing that typhoid
fever, scarlatina, diarrhcea, and other epidemic diseases,
commit fearful ravages amongst the populations exposed
to the pestiferous influences it exercises, and they express
the opinion that to it may be attributed much of the
responsibility for the high death-rate of South Lancashire
towns. They have, however, been unable to obtain con-
clusive evidence of this owing to the incompleteness of
the health statistics. They express astonishment at the
frequent inability of Health Boards to inform them of the
death-rate in their districts, still less to give information
as to particular parts of them.
  It is a very general opinion of medical men that the
presence of an extremely minute amount of organic im-
purity may, under certain obscure conditions, render
water unwholesome, and capable of causing or propagat-
ing disease, especially if that impurity be of aninial origin.
Sewage is the source from which such impurity is most
likely to originate in a specially dangerous form, and it
appears the amount capable of causing injury may be so
small as to have no influence on the outward appearance
of the water. To the smell, sight, and taste all may seem
innocuous, and yet there may be present an infinitesimal
portion of substance rivalling in potency the most viru-
lent poison.
  That water subject to such contamination is thereby
rendered unfit for human use, and repugnant to every
sense of decency, can, it is believed, require no arguments
to be admitted. That the use of such water is, more-
over, dangerous and unwholesome, would seem to be sug-
gested by a knowledge of the changes which excretal
refuse naturally undergoes, and of the circumstances at-
tending those changes.  The medical officers of Her
Majesty's Privy Council, after specially studying numerous
instances of the outbreak of typhoid fever and cholera,
have almost invariably found that the prevalence of these
;and other epidemic diseases was accompanied by the use
579
of water that had been polluted with drainage from cess-
pools or sewers. But at the same time it has been im-
possible to detect or demonstrate, by chemical analysis,
the presence in the water of anything to which a fatal in-
fluence or the production of disease can be ascribed.
This fact, however, does not in any degree, afford a ground
for regarding the water as free from suspicion.  Such
reasoning would apply with equal force to sewage itself, for
chemical analysis does not indicate the presence in it of
anything specially noxious.
  It has indeed often been alleged that if sewage be
mixed with twenty times its volume of river water, the
organic matter which it contains will be oxidised com-
pletely while the river is flowing a dozen miles or so.
Considering the importance of the subject, it is surprising
that this assertion, though confidently made in many
instances, should hitherto have rested upon no more solid
foundation than mere opinion. But at last the test of
positive inquiry has been applied by the Rivers Pollution
Commissioners. The composition of the water of the
Irwell, the Mersey, and the Darwen at various points in
the course of these rivers has been ascertained with due
regard to complications introduced by the influx of unpol-
luted affluents. The results have shown that when the
temperature is not above 640 F., a flow of from i i to 13
miles produces but little effect upon the organic material
dissolved in the water. Examination of the gases dissolved
in water containing an admixture of sewage led to the
same result. Lastly, experiments devised to augment the
effect of atmospheric oxidation on such water, so as to
represent a flow of from 96 to 192 miles in a river at the
rate of I mile an hour, showed that the reduction of organic
carbon in the water amounted to only 6-4 and 25 - per cent.,
that of organic nitrogen to 28 4 and 33-3 per cent., though
the temperature was 68° F. Thus whether we examine
the organic pollution of water at different points of a river,
or the rate of disappearance of the organic material of
sewage mixed with water and agitated in contact with air,
or the rate at which dissolved oxygen disappears in water
polluted with 5 per cent. of sewage, we are in each case
led to the inevitable conclusion that the oxidation is very
slow-so slow in fact that it is safe to infer there is no
river in the United Kingdom long enough to effect the
complete transformation of sewage in that way.
  These results are further confirmed by evidence as to
the state of the rivers in the Mersey and Ribble basins -
they are consistent with the opinions of chemists, and
they are opposed only by dogmatic assertions destitute
of proof.
  To illustrate the extent to which the polluted state of
Lancashire rivers is a disadvantage to manufacturers, the
Commissioners state that thirty-nine of the firms who are
carrying on different branches of trade in the basins of
the Mersey and Ribble, estimate the benefit they would
derive if the river water were fit for their use at no less
than  lo,1571. a year, while one calico-printing firm
estimates the gain to them at 3,oool. a year. The number
of manufacturers who have given these estimates form
only a small fraction of the total number in the district.
MAGNETIC AND SUN SPOT PHENOMENA
              FOR FEBRUARY, i870.
        (As recorded at the Kew Observatory.)
N N February ist about 5 p.m. there occurred a very
0 J considerable disturbance of the three magnetic
elements, which lasted until about 2 o'clock in the early
morning of the next day. The tendency of this disturbance
was to diminish the declination and the horizontal force,
while on the other hand the vertical force was increased
during the first half of the disturbance and diminished
during the second. The oscillations of the declination
were very large. The disturbance was accompanied with