Phosphate of lime 2·32
Carbonate of lime 1·94
Silica 6·28
-----
10·54
The deposit from another gallon weighed 55 grains, of which 21·22 were
combustible, being composed of animal matter “rich in nitrogen,” some
vegetable matter, and a quantity of fat. Of this matter 33·75 grains
consisted of
Phosphate of lime 6·81
Oxide of iron 2·01
Carbonate of lime 1·75
Sulphate of lime 1·53
Earthy matter and sand 21·65
-----
33·75
Other Reports and other evidence show that what is described as “earthy
matter and sand” is the mac, mud, and the mortar or concrete used
in pavement, washed from the surface of the streets into the sewers
by heavy rains; otherwise for the most part the proper load of the
scavager’s cart.
Further analyses might be adduced, but with merely such variation in
the result as is inevitable from the state of the weather when the
sewage is drawn forth for examination; whether the day on which this is
done happens to be dry or wet[66].
It has been ascertained, but the exact proportion is not, and perhaps
cannot be, given, that the extent of covered to uncovered surface in
the district drained by the King’s Scholars’ Pond Sewer was as 3 to 1,
while that of the Ranelagh Sewer, not far distant, was as 1 to 3, at
the time of the inquiry (1848).
“It could not be expected, therefore,” says the Report, “that the
Ranelagh Sewer (which, moreover, is open to the admission of the tide
at its mouth), in the quantity or quality of the manure produced, could
bear any proportion to the King’s Scholars’ Pond Sewer.”
Mr. Smith, of Deanston, stated in evidence, that the average quantity
of rain falling into King’s Scholars’ Pond Sewer was 139,934,586 cubic
feet in a year, and he assumes 6,000,000 tons as the amount of average
minimum quantity of drainage (yearly), yielding 4 cwt. of solid matter
in each 100 tons = 1 in 500.
Dr. Granville said, on the same inquiry, that he should be sorry to
receive on his land 500 tons of diluted sewer water (such as that from
the uncovered Ranelagh Sewer) for 1 ton of really fertilizing sewage,
such as that to be derived from the King’s Scholars’ Pond Sewer.
I could easily multiply these analyses, and give further parliamentary
or official statements, but, as the results are the same, I will merely
give some extracts from the evidence of Dr. Arthur Hassall, as to the
microscopic constituents of sewage-water:--
“I have examined,” he said, “the sewer-water of several of the
principal sewers of London. I found in it, amongst many other things,
much decomposing vegetable matter, portions of the husks and the hairs
of the down of wheat, the cells of the potato, cabbage, and other
vegetables, while I detected but few forms of animal life, those
encountered for the most part being a kind of worm or anælid, and a
certain species of animalcule of the genus monas.”
“How do you account,” the Doctor was asked, “for the comparative
absence of animal life in the water of most sewers?” “It is, doubtless,
to be attributed,” he replied, “in a great measure, to the large
quantity of sulphuretted hydrogen contained in sewer-water, and which
is continually being evolved by the decomposing substances included in
it.”
“Have you any evidence to show that sewer-water does contain
sulphuretted hydrogen in such large quantity as to be prejudicial and
even fatal to animal life?” “With a view of determining this question,
I made the following experiments:--A given quantity of Thames water,
known to contain living infusoria, was added to an equal quantity of
sewer-water; examined a few minutes afterwards, the animalculæ were
found to be either dead or deprived of locomotive power and in a dying
state. A small fish, placed in a wine glass of sewer-water, immediately
gave signs of distress, and, after struggling violently, floated on its
side, and would have perished in a few seconds, had it not been removed
and placed in fresh water. A bird placed in a glass bell-jar, into
which the gas evolved by the sewer-water was allowed to pass, after
struggling a good deal, and showing other symptoms of the action of the
gas, suddenly fell on its side, and, although immediately removed into
fresh air, was found to be dead. These experiments were made, in the
first instance, with the sewer water of the Friar-street sewer (near
the Blackfriars-road); they were afterwards repeated with the water
of six other sewers on the Middlesex side, and with the same result,
as respects the animalculæ and fish, but not the bird; this, although
evidently much affected by the noxious emanations of the sewer-water,
yet survived the experiment.”
“Would you infer from these experiments that sewer-water, as contained
in the Thames near to London, is prejudicial to health?” “I would, most
decidedly; and regard the Thames in the neighbourhood of the metropolis
as nothing less than diluted sewer-water.”
“You have just stated that you found sewer-water to contain much
vegetable matter, and but few forms of animal life; the vegetable
matter you recognised, I presume, by the character of the cells
composing the several vegetable tissues?” “Yes, as also by the action
of iodine on the starch of the vegetable matter.”
“In what way do you suppose these various vegetable cells, the husks of
wheat, &c., reach the sewers?” “They doubtless proceed from the fæcal
matter contained in sewage, and not in general from the ordinary refuse
of the kitchen, which usually finds its way into the dust-bin.”
“Sewer-water, then, although containing but few forms of animal life,
yet contains, in large quantities, the food upon which most animalculæ
feed?” “Yes; and it is this circumstance which explains the vast
abundance of infusorial life in the water of the Thames within a few
miles of London.”
The same gentleman (a fellow of the Linnæan Society, and the author of
“A History of the British Fresh-water Algæ,” or water-weeds considered
popularly), in answer to the following inquiries in connection with
this subject, also said:--
“What species of infusoria represent the _highest_ degree of impurity
in water?” “The several species of the genera _Oxytricha_ and
_Paramecium_.”
“What species is most abundant in the Thames from Kew Bridge to
Woolwich?” “The _Paramecium Chrysalis_ of Ehrenberg; this occurs in
all seasons of the year, and in all conditions of the river, in vast
and incalculable numbers; so much so, that a quart bottle of Thames
water, obtained in any condition of the tide, is sure to be found, on
examination with the microscope, to contain these creatures in great
quantity.”
“Do you find that the infusorium of which you have spoken varies in
number in the different parts of the river between Kew Bridge and
Woolwich?” “I find that it is most abundant in the neighbourhood of the
bridges.” [Where the outlet of the sewers is common.]
“Then the order of impurity of Thames water, in your view, would be the
order in which it approaches the centre of London?” “Yes.”
“You find then, in Thames water, about the bridges, things decidedly
connected with the _sewer water_, as vegetable and animal matter
in a state of decomposition?” “I do; about the bridges, and in the
neighbourhood of London, there is very little living vegetable matter
on which animalculæ could live; the only source of supply which they
have is _the organic matter contained in sewer-water_, and which is to
be regarded as the food of these creatures. Where infusoria abound,
under circumstances _not_ connected with sewage, vegetable matter in a
living condition is certain to be met with.”
Respecting the _uses of the sewage_, I may add the following brief
observations. Without wishing in any way to prejudice the question
(indeed the reader will bear in mind that I have all along spoken
reprovingly of the waste of sewage), I am bound to say that the
opinions I heard during my inquiry from gentlemen scientifically and,
in some instances, practically familiar with the subject, concurred in
the conclusion that the _sewage_ of the metropolis cannot, with all
the applications of scientific skill and apparatus, be made either
sufficiently portable or efficacious for the purposes of manure to
assure a proper pecuniary return. In this matter, perhaps, speculators
have not traced a sufficient distinction between the liquid manure of
the sewers and the “_poudrette_,” or dry manure, manufactured from the
more solid excrementitious matter of the cesspools, not only in Paris,
but, until lately, even in London, where the business was chiefly in
the hands of Frenchmen. The staple of the French “_poudrette_” is
_not_ “_sewage_,” that is, the outpourings of the sewers--for this is
carried into the Seine, and washed away with little inconvenience,
as the tide hardly affects that river in Paris; but it is altogether
“_cesspoolage_,” that is, the deposit of the cesspools, collected in
fixed and moveable utensils, regulated by the “universal” police of
Paris, and conveyed by Government labourers to the Voirées, which are
huge reservoirs of nightsoil at Montfauçon, about five miles, and
in the Forest of Bondy, about ten miles, from the centre of Paris.
The London-made manure also was all of cesspoolage; the contents of
the nightman’s cart being “shot” in the manufacturer’s yard; and
when so manufactured was, I believe, without exception, sent to the
sugar-growing colonies, the farmers in the provinces pronouncing it
“too hot” for the ground. The same complaint, I may observe, has been
made of the French manufactured cesspool manure. I heard, on the other
hand, opinions from scientific and practical gentlemen, that the
sewer-water of London was so diluted, it was not profitably serviceable
for the irrigation of land. All, however, agreed that the sewage of the
metropolis ought not to be wasted, as it was certain that perseverance
in experiment (and perhaps a large outlay) were certain to make sewage
of value.
The following results, which the Board of Health have just issued in a
Report, containing “Minutes of Information attested on the Application
of Sewer-water and Town Manures to Agricultural Production,” supply
the latest information on this subject. The Report says first, that
“to be told that the average yield of a county is 30 bushels of wheat
per acre, or that the average weight of the turnip crop is 15 tons
per acre, means very little, and there is little to be learned from
such intelligence; but if it is shown that a certain farm under the
usual mode of culture yielded certain weights per acre, and that the
same land, by improved applications of the same manure, by the use of
machinery, and by _employing double the number of hands, at increased
wages_, is made to yield _four fold_ the weight of crop and of _better
quality_ than was previously obtained, a lesson is set before us worth
learning.”
It then proceeds to cite the following statements, on the authority of
the Hon. Dudley Fortescue, as to the efficiency of sewage-water as a
liquid manure applied to land.
“The first farm we visited was that of Craigentinney, situated about
one mile and a half south-east of Edinburgh, of which 260 Scotch acres”
(a Scotch acre is one-fourth more than any English acre) “receive a
considerable proportion of such sewerage as, under an imperfect system
of house-drainage, is at present derived from half the city. The
meadows of which it chiefly consists have been put under irrigation
at various times, the most recent addition being nearly 50 acres laid
out in the course of last year and the year previous, which, lying
above the level of the rest, are irrigated by means of a steam-engine.
The meadows first laid out are watered by contour channels following
the inequalities of the ground, after the fashion commonly adopted
in Devonshire; but in the more recent parts the ground is disposed
in ‘panes’ of half an acre, served by their respective feeders, a
plan which, though somewhat more expensive at the outset, is found
preferable in practice. The whole 260 acres take about 44 days to
irrigate; the men charged with the duty of shifting the water from
one pane to another give to each plot about two hours’ irrigation
at a time; and the engine serves its 50 acres in ten days, working
day and night, and employing one man at the engine and another to
shift the water. The produce of the meadows is sold by auction on the
ground, ‘rouped,’ as it is termed, to the cow-feeders of Edinburgh,
the purchaser cutting and carrying off all he can during the course of
the letting, which extends from about the middle of April to October,
when the meadows are shut up, but the irrigation is continued through
the winter. The lettings average somewhat over 20_l._ the acre; the
highest last year having brought 31_l._, and the lowest 9_l._; these
last were of very limited extent, on land recently denuded in laying
out the ground, and consequently much below its natural level of
productiveness. There are four cuttings in the year, and the collective
weight of grass cut in parts was stated at the extraordinary amount of
80 tons the imperial acre. The only cost of maintaining these meadows,
except those to which the water is pumped by the engine, consists in
the employment of two hands to turn on and off the water, and in the
expense of clearing out the channels, which was contracted for last
year at 29_l._, and the value of the refuse obtained was considered
fully equal to that sum, being applied in manuring parts of the land
for a crop of turnips, which with only this dressing in addition
to irrigation with the sewage-water presented the most luxuriant
appearance. The crop, from present indications, was estimated at from
30 to 40 tons the acre, and was expected to realize 15_s._ the ton
sold on the land. From calculations made on the spot we estimated the
produce of the meadows during the eight months of cutting at the keep
of ten cows per acre, exclusive of the distillery refuse they consume
in addition, at a cost of 1_s._ to 1_s._ 6_d._ per head per week. The
sea-meadows present a particularly striking example of the effects of
the irrigation; these, comprising between 20 and 30 acres skirting the
shores between Leith and Musselburgh, were laid down in 1826 at a cost
of about 700_l._; the land consisted formerly of a bare sandy tract,
yielding almost absolutely nothing; it is now covered with luxuriant
vegetation extending close down to high-water mark, and lets at an
average of 20_l._ per acre at least. From the above statement it will
be seen how enormously profitable has been the application in this case
of town refuse in the liquid form; and I have no hesitation in stating
that, great as its advantages have been, they might be extended four
or five fold by greater dilution of the fluid. Four or five times the
extent of land might, I believe, be brought into equally productive
cultivation under an improved system of drainage in the city, and a
more abundant use of water. Besides these Craigentinney meadows, there
are others on this and on the west side of Edinburgh, which we did
not visit, similarly laid out, and I believe realizing still larger
profits, from their closer proximity to the town, and their lying
within the toll-gates.”[67]
Such, then, are said to be the results of a practical application of
sewer-water. The preliminary remark of the Board of Health, however,
applies somewhat to the statement above given; for we are not told what
the _same land_ produced before the liquid manure was applied; nor are
we informed as to the peculiar condition and quantity of the land near
Craigentinney, and how it differs from the land near London.
The other returns are of liquid manures, of which sewer-water formed no
part, and, therefore, require no special notice of them. The following
observations are, however, worthy of attention:--
“The cases above detailed furnish some measure of the possible
results attainable in cultivation, especially corroborated as they
are by others which did not on this occasion come under our personal
observation, but one of which I may mention, having recently examined
into it, that of Mr. Dickinson, at Willesden, who estimates his yield
of Italian rye-grass at from 80 to 100 tons an acre, and gets 8 or
10 cuttings, according to the season; and as there is no peculiar
advantage of soil or climate (the former ranging from almost pure sands
to cold and tenacious clays, and the latter being inferior to that of
a large proportion of England) to prevent the same system being almost
universally adopted, they give some idea of the degree to which the
productiveness of land may be raised by a judicious appliance of the
means within our reach. When it is considered that such results may,
in the vicinity of towns and villages, be most effectually brought
about by the instant removal of all those matters which, when allowed
to remain in them, are among the most fruitful sources of social
degradation, disease, and death, one cannot but earnestly desire
the furtherance of such measures as will ensure this double result
of purifying the town and enriching the country; and as the facts I
have stated came at the same time under the notice of the gentleman I
mentioned above, under whose able superintendence the arrangements for
the water-supply and drainage of several towns are now in course of
execution, I trust it will not be long before this most advantageous
mode of disposing of the refuse of towns may be brought into practical
operation in various parts of the country.
“I have, &c.,
“D. F. FORTESCUE.
“General Board of Health.”