The Sun.
London, England, 1865-02-13 00:00:00

The Thames Embankment.

Itivill not be for the want of excellent practical ex-
amples of the science if the general public do not
-become in a rough and ready sort of way tolerable
engineers. No one can walk far now-a.days, or
journey much by road or rail, without coming in
sight of some stupendous mechanical contrivance for
facilitating traffic or erecting bridges and buildings.
The Thames Tunnel is a mere trifle as an engineer-
ing work to what has been accomplished in the sub-
terranean railway, and the subterranean itself is
about to be outdone by its own extension, for
the completion of which it will be necessary to make
a second tunnel underneath the first. Tunnels,
viaducts, and scaffoldings are, in fact, familiar to
every one. Of the latter we have in London just
now four excellent specimens—that for the bridge
at Cannon-street, that which forms the temporary
bridge at Blackfriars, that for the removal of the
old bridge, and that which will soon dam out some
10 or 11 acres of - the Thames, and reclaim it
for the great Embankment between Westminster
and Waterloo. Just now the works connected
with this really gigantic undertaking are in full ope-
ration, and the whole series of processes by which
cofferdams are commenced, continued, and com-
pleted can be watched in all their stages, from the
first pile driven at Hungerford-bridge to the perfect
series of caissons which now shut out the Thames
from the large area enclosed below Westminster.
It will probably be very long before Londoners will
again have such an opportunity of studying practi-
cal engineering on the most extensive scale. Steam
and hand pile-drivers, steam and hand pumps,
steam cranes and travellers, with steam machinery
for driving air-pumps ; men working at the top of
lofty timbers, or down in the darkness far below
the bed of the river, filling the cofferdams by sluices
to flush out the mud, and then pumping it out again
by steam ; with stones, bricks, rubbish, offal, dirty
water, and all the unsavoury flotsam and jetsam
which go to make up the river Thames—these and
a hundred other operations and contrivances are
always in work day after day, and from morning to
night.

The works next to Westminster-bridge are those
which attract the greatest amount of public atten-
tion, for there everything can be watched from the
Pumping out of water, to the puddling in of clay be-
tween the timbers of the cofferdam, and here also
can be seen the whole plan of struts and cross
timbers which enables the iron caissons to keep out
the whole flood of the Thames for a depth of 40ft.
above them, and resist a pressure of no less than
120 tons on each caisson. From no point of the
river can the whole system on which the Embank-
ment is to be built be better seen than here, for
here are both the iron and timber embankments
behind which the massive granite face of the real
Embankment is to rise. The method of building this
iron cofferdam, though very simple, is from its very
simplicity of great interest. The caissons are elipti-
cal tubes of wrought iron rings or belts, each ring or
belt being 12ft. long by 7ft. wide and 4ft. deep, with
a flange or edge that admits of the rings being bolted
one to another. Three or four of these rings are
bolted together and sunk between guiding piles to
their proper position in the bed of the river, then
others are similarly added on till the height of the
whole is sufficient to raise them above high-water
mark, and the weight of the whole is sufficient to
sink the hollowtube of iron which they form through
the soft mud on which they rest and keep them,
water-tight from below. When this result has been
attained the water is pumped out and the tube gra-
dually weighted with iron to force it lower till it has
reached a fair depth, and has a firm hold in the
ground, when the agency of the pneumatic machi-
nery is called into play. After the workmen have
descended and dug out the gravel and shingle to a
depth of some 2ft. or 3ft. below the lowest in-
ternal edges of the tube, a weight of 60 tons of iron
is placed upon it from the inside, with an air -tight
iron cover, which closes in the top. Through an
aperture in the top of this cover the air is forced in
by steam power till it has reached a pressure of Sib.
to the inch—a pressure which dilates the tube more
than half an inch in all directions, when the air is
suddenly released, and the cylinder as suddenly
contracts and sinks through the earth -which it has
itself enlarged to a depth of 2ft. or 3ft. lower. This
process has to be repeated over and over again till
all the superincumbent mud and silt and gravel has
been penetrated, and that mysterious geological
compound like heavy, brown plaster of Paris,
though as hard as marble, and known by the name
of the London clay, has been reached, when no effort
of modern engineering can contrive to get any-
thing much further. The presence of this London
clay on the banks of the Thames varies in an almost
unaccountable degree. In some cases it crops up
close under the mud ; in others it can only be
found after a laborious penetration of 40ft. below
it. Thus one caisson may only penetrate 10ft. or
or 12ft. below the surface, and its next neighbour
may have to gO to a depth of 40ft. or 45ft. Once,
however, that it is reached the sinking of the cais-
sorts stops, they are merely filled up to the level of
low-water mark with solid concrete, and thus filled
they will remain till the time shall come when the
Embankment itself will totter, for behind them it
is intended that its foundations are to be built, and
it is to be hoped to last for centuries to come. The
lower parts of these iron banks are never to be
removed. The upper parts, which now shut out
the Thames at Westminster, will of course be taken
away as the wall of the real embankment is built
behind them.

To take this part as exemplifying the process of
construction, we have here a length of 240 feet of
iron caissons towards the river, shut in by a cross
dam near Montague-house, which reaches back
from the caissons to the shore, so as to enclose a
water-tight space of nearly an acre and a quarter.
This space, though enough to make a fair orna-
mental lake, the screw pumps of Messrs. Wood-
-wards and Murray soon cleared of water, and as
the supporting mass of this water inside diminished
and the weight of that shut out increased powerful
timber struts have been added to the caissons till all
are now said to be equal to more than double the
weight which a full spring tide can bring against b
them. From this space the mud has n
flushed
out, and here in this space next week theee,, labourThe
first e
building the Embankment proper will be'
first operation will be to clear out all the shingle
and gravel to a depth of 14 feet behind the cais-
sons, or more than 40 feet below high-water mark,
additional and still more powerful timber sup-
ports being added to the caissons as the men
get lower down beneath the river, and the pres-
sure of the great mass of water overhead in-
creases. This somewhat hazardous work will be
done in short sections at a time, and as fast as the
required depth is reached—that is to say, on a level
with the concrete with which the caissons are half
filled—the excavation will cease, and the space is
then to be filled up rapidly with solid concrete. On
this will be laid the brickwork, and over all, on the
river face, the solid blocks of granite, which are to
rise in a massive wall to a height of 30ft. above the
river. It may give a good rough general idea of the
gigantic proportions of this work if we merely men-
tio
n the quantities with which Mr. MrFurness the con-
tractor for the
first portion only, *from Westminster
to Waterloo-b
cartloads of earth have
has to deal. First, then, 71,000
of
concrete to be excavated, and 60,000
cartloads
have to be " tipped in," 4,000
rods, or nearly 70,000 tons of brickwork have to be
laid and faced with 30,000
betens of granite, and the
whole has afterwards
Lod those who are now
400,000 cortloads of earth. filled up behind with
so often blocked up in the Str
ladbeY with the long
earth for
slow-
tin
moving, dismal string
of carts
yet
ts to that at the
that
the Embankment it will be sorry
di
least 200,000 more cartloads havenuisanceva:ss
way. We fear, however, that the
voidable. It is not, as in the case of a railway a tula.
em-
bankment, where a tramway takes any quantity of
earth from one end of the line where it is to be got
to the other end where it cannot be got at all. In the
case of the Embankment both ends are equally in
want of earth, and none is to be had of any sort but
what the contractors buy in different parts of London,
and this ever-varying quantity, of course, can only
be brought in carts, and the carts can only come
along the Strand. For the present, therefore, we
fear that an abatement of this nuisance, however

ardently to be desired, is not yet to be looked for.
Another section of the Embankment besides that
we have mentioned, and which Mr. Fu' ness is
hurrying forward with the utmost possi'o7e speed, is
that between Montague-house and I ungerford,
where the steam piledrivers are busy eve) y minute of
the day. This section is composed entirely of wood.
The cofferdam is formed of wood piles in two rows
seven feet apart, and driven through the shingle as
close as they can be got together. The interval be-
tween the first and second row is then " puddled"
in in the usual manner with stiff clay till it is water-
tight, when the river is pumped out, the cofferdam
strengthened with struts, as in the case of the iron
caissons, and the work of excavation, filling in with
concrete, and, finally, building will go on as behind
those we have already mentioned. Altogether, no
less than 1,300 feet out of the 2,000 feet of the first
section to Waterloo-bridge have been dammed in
with piles or caissons, and this length will be subdi-
vided by nine cross sections leading backwards, so as
to render the work of pumping and subsequently
building as easy7as possible. The length, however
already enclosed towards the river, and over which'
the water now flows behind the cofferdam only on
sufferance, is very great, and will, when the Thames
is entirely shut out, give a space of nearly 11 acres
reclaimed from an unsightly, muddy, foreshore into
one of the noblest, and, we may add, one of the most
needed, thoroughfares in Europe.
Nothing is, of course, yet being done either with the
low level sewer or the subway which is to pass along
the whole length of the Embankment. The former will
be a simple circular tunnel of nine feet in diameter,
and laid almost as low as the foundations of the Em-
bankment itself. The subway above it will be
nine feet wide by seven feet high for the gas and
water-pipes and telegraphic wires, so as to do away
with all that endless competition between gas and
water companies as to who shall oftenest pull up the
pavements and stop the greatest number of streets
in the course of the year. These works, how-
ever, are likely to be kept well in hand as the Em-
bankment progresses, and it is only to be hoped that
the railway which is to pass under it and behind it
may be in the same state of readiness. Certainly,
the works of the latter ought to *proceed as the
granite face of the Embankment itself advances, or
else on such very new-made ground there might be
a movement caused by the railway works which
would be as injurious to the railway as to the Em-
bankment itself. We believe, however, that in a
short time it is intended to commence this railway,
which will complete Mr. Fowler's celebrated metro-
politan inner circle.

The Corporation of London and the Utili-

sation of Sewage.

The Coal, Corn, and Finance Committee of the
Corporation of London have just presented a re-
port on this subject to the Court of Common Coun-
cil.

They state that on the 12th of November last
they presented a report to the Common Council, on
the reference to them to consider the report of the
Select Committee of the House of Commons on
Sewage, in which attention was drawn to the facts
that town sewage, as proved by the evidence, is a
manure suitable for all crops ; that when poured
over land in enormous quantities, as at Edinburgh
and Rugby, the land was reduced to the condition of
a morass, the produce was inferior and the manure
wasted ; but that, when applied in moderation, like
any other fertilising agent now in use, the results
were most satisfactory. Keeping these facts in view,
and taking into account the enormous value of the
London sewage, the Corporation Committee were
of opinion that the area for its economic and profit-
able utilisation should not be less than from
500,000 to 600,000 acres. The committee, how-
ever, not having had sufficient evidence before
them to enable them to say whether or not it
would be possible to distribute the sewage over such
an area, were of opinion that this point, upon which
the entire question of economic and profitable
sewage utilization depends, should be decided by a
Parliamentary inquiry. The committee, therefore,
concluded their report by recommending that be-
fore a concession of the sewage was made to any
party a further and more searching investigation
should be undertaken by Parliament into every
scheme for its utili7'ttion. This report was agreed
to by the Court, and it was referred back to the
committee to take such steps therein as might be
deemed expedient, with instructions to put them-
selves in communication with Her Majesty's Go-
vernment, with a view to the further investigation
of the question. Acting on these instructions a de-
putation of the committee had an interview with
Lord Palmerston, and afterwards, at his Lordship's
suggestion, with Sir George Grey. Sir George, at
the end of a long interview, said that without pledg-
ing himself to any particular course the inclination
of his opinion was that further inquiry was neces-
sary. The committee were the more anxious that
this inquiry should be made in order to protect not
only the rate-payers of the metropolis, but the
country at large from being misled as to the agricul-
tural and commercial value of sewage and the most
profitable method for its utilisation, by the bad re-
sults obtained from the numerous experiments car-
ried on at Rugby by Mr. John Bennet Lawes for
the Royal Sewage Commission. These results
themselves prove that the system of large dressings
upon which they were carried out is a mistake, and
yet, strangely enough, they are cited by the advo-
cates of this wasteful system to prove that it will
not pay commercially to utilise sewage on the eco-
nomic principle, than which nothing can be more
illogical. The committee find that Baron Liebig,
commenting on the evidence given by Mr. Lawes be-
fore Lord Robert Montagu's Select Committee in
support of these experiments, has lately written as
follows :—" The experiments made at Rugby are
excellent specimens to show whichi way ought not
to be followed to get a fair estimation of the value
of sewage. The experiments succeeded in this, that
they transformed very good land into a swamp.
There was a very large amount of sewage matter
that ran away ; but they would use a greal deal
more if sewage could be got for nothing." The re-
port of the committee was unanimously adopted by
the Court, and a copy was forthwith sent to the
Metropolitan Board of Works. That Board, how-
ever, on the 15th of the same month, made a con-
cession of the sewage of the north side of the me-
tropolis to Messrs. Hope and Napier; the committee
have, therefore, considered the scheme of those gen-
tlemen, on which they report as follows :
" The committee find that Messrs. Hope and
Napier propose to take the sewage from a point near
Abbey Mills and conduct it by means of a brick cul-
vert to the seacoast of Essex, where it is to be dis-
charged over a portion of the Foulness Sands and
Dingie Flats, which arc to be reclaimed from the
ocean by means of a great embankment, but the
precise area to be inclosed the committee have'
been unable to ascertain. In their original tender,
bearing date the 30th of October, 1861, they spoke
of an area of 30,000 to 40,000 acres which were to
be inclosed, but in their letter to the Chairman of
the Metropolitan Board of Works, dated the 25th
of November, 1861, they mentioned 20,000 acres
only. When these gentlemen, together with their
engineer, Mr. Hemans, were under examination be-
fore Lord Robert Montagu's Select Committee, Mr.
Hemans was asked, ' You propose to putthe sewage
of the north side of the metropolis on 20,000 acres
of the Dingie Flats and Maplin Sands, do you not ?
—Yes.' Mr. Hope, however, was asked,
give up the Dingie Flats and confine yourse 'Youlf to a
com-
mittee smaller area, do you not
.?—Yes.. That we
e The have
one
on both practical and scientific advice.'
find that this alteration would reduce the area
to be reclaimed from the ocean to 12,000 acres.
From Mr. Hope's answer to question 575 the com-
mittee find that these gentlemen originally ' did
not contemplate the possibility of inducing the
farmers to take the sewage over an extended
area ;' but from their evidence before the com-
mittee
i t
it appears they have changed their opinion
on this point also,
and that they propose to distri-
buteover as large an area as can be commanded
f
by gravitation rom the culvert. In answer to ques-
tion 605 Mr.
that the Hope said, ' Mr. Hemans estimates
but Mr. areaHernans co
inmmanded would be 20,000 acres ;'
that an area of to answer
to
question 618, states, osoo acres is commanded, and

could be watered by this culvert.' The committee
find that since the tender of Messrs. Hope and
Napier was accepted by the Metropolitan Board of
Works, Mr. Hemans, in a letter which appeared in
the newspapers of Thursday, Nov. 47, gave a de-
scription of their present plan, which largely modi-
fies that one approved by the Board. From Mr.
Hemans' letter the committee gather that, in addi-
tion to the Maplin Sands, the Dingle Flats, which
Mr. Hope informed the Select Committee had been
abandoned 4 on both practical and scientific advice,'
are to be reclaimed from the ocean ; that the em-
bankment wall was not to be constructed, as origi-
nally intended, along the edge of the deep water, in
order to inclose the 12,000 acres, but nearer the
shore ; ' the remaining portion,' as Mr. Hemans
observes, ' will then, by the ordinary process of na-
ture, warp up, and ultimately the whole 25,000
acres will be reclaimed ; perhaps a good deal more.'
From the answers, however, of Mr. Hopkins, C.E.,
before Lord Robert Montagu's Select Committee, to
questions from 1,010 to 1,014 inclusive, the com-
mittee are induced to think that the remaining por-
tion of these sands would not warp up for several
hundred years. Mr. Hemans also stated in his let-
ter, that 80,000 acres could be commanded from the
culvert, but he did not say how much of this land
lies beneath the level of high water in the Thames,
and which from excessive moisture and defective
drainage would be unfit for the profitable reception
of a liquid manure during the greater portion of the
year. The committee find, from Mr. Bazalgette's
replies to certain questions, that the sewage of the
north side of the metropolis is estimated at 168,033,115
tons per annum, which, according to the analysis of
Hofmann and Witt, would contain an amount of
fertilising matter equal to 134,424 tons of Peruvian
guano, and taking guano sold at the present retail
price of £l3 128.6 d. per ton as the standard of value,
this would be worth £1,831,557. The committee
also find that the volume, and consequently the
value of the sewage, must increase year by year
with the population ; while Baron-Liebig has given
it as his opinion that the value of the manure may
at once be doubled by the introduction of, compara-
tively speaking, a very small portion of superphos-
phate of lime. It is evident that Messrs. Hope and
Napier could not possibly recover in crop off their
maximum area anything like the present value of
their manure, without making any allowance for
landlords or farmers' profits, taxes, interest on capi-
tal, working expenses, or other charges ; much less
could they recover the value of the increased volume
of the sewage in future years. Indeed the committee
find, from the evidence of those gentlemen, that bas-
ing their idea of the value of the sewage upon the re-
sults obtained by Mr. Lawes, whose system they
follow, they do not calculate on a larger income to
divide with the ratepayers thah £390,445 a year, as
appears from Mr. Hope's answer to question 679,
out of which is to be deducted a preference dividend
of 73. per cent. on the capital before the ratepayers
are to receive any payment for their property. The
committee have examined Baron Liebig's most valu-
able report, and desire briefly to draw the attention
of the Court to the opinion arrived at by this great
authority as to the value of the sewage and the proper
method for its utilisation. The committee find that
Baron Liebig's analysis of the various fertilising mat-
ters found in sewage and in Peruvian guano have led
him to the conclusion that in 828 tons of the London
sewage, taking its total annual amount at 226,000,000
tons, there is asmuch ammonia as in one ton of Pesu-
vian guano ; and estimating the value of the ammonia,
phosphoric acid, and potash found in a ton: of guava
to be worth £7 145., he is of opinion that the fertilis-
ing matter contained in one ton of sewage is worth
1-84 d., and the annual amount of, the metropolitan
sewage is worth £2,040,715. He, however, further
states—',lf the ammonia be reckoned at the price
farmer pays at present for it in Peruvian guano, the
ton of sewage water would be worth something
more than the double of that price.' This would
give £4,081,430 as the annual value of the metro-
politan sewage—a sum somewhat larger than that
arrived at by the committee, basing this estimate on
the analysis of Messrs. Hofmann and Witt and the
present retail price of Peruvian guano, which price
must necessarily rule that of every other manure.
The committee further find that Baron Liebig points
attention to the power of soil to abstract from sewage
the fertilising matters therein contained, but that of
all soils pure sand possesses this power in the
smallest degree ; and with reference to the dilution
of the sewage he states :—' A series of experiments
with artificial sewage water proved that a dilution
with water as great as that of the sewage of the
metropolis in no wise diminishes the absorbing
effect of the soil. I found, moreover, last summer,
by experiments regarding the growth of plants, that
a soil completely saturated with manuring matter
did not, as:might be supposed, further the develop-
ment of the plants' growth, for to many, on the
contrary, it was prejudicial.' The committee also
find that Baron Liebig conclusively proves the fitness
of sewage as a manure suitable for arable land and
general farming purposes, and emphatically points
attention to the error of continually applying one
dekription of manure to land. He states :—' No
one will ever think of supplying the full effect of
farmyard dung by the employment of phosphates or
guano, nor is it to be done either by the use of sew-
age. The chief value of sewage lies in this, that by its
application the effects of phosphates, guano and stable
dung are made sure and lasting, and the crops raised
to that maximum which the soil can produce, be-
cause, by means of sewer water these elements are
given which are wanting in those other manures, or
are preseht in them in but small quantities.' Baron
Liebig, ho wever, shows by a comparison between the
constituencies of sewage and those required for the
proper nourishment of grass that although it will un-
doubtedly benefit that crop, yet that it is less suit-
able for it than for any other to which it could be
applied, and will yield a much less profitaleb return,
and that whereas the fertilising matter contained in
a ton of the London sewage, if applied 'to arable
land' would be worth 1.84 d., taking guano sold at
£7 14s. per ton as ;the standard, it would only be
worth 2.8 farthings if used for grass, that being, as
Baron Leibig states, ' three-eighths of that which I
have computed its absolute value to be. The reason
of this difference is, that sewage water contains an
excess of ammonia and phosphoric acid which is
without effect on the growth of grass, and for this
reason is not paid for.' And further on, speaking of
the application of sewage to thesame crop he states,
' In all localities which by nature are adapted for the
employment of sewage, its use is unquestionably an
advantage. But if a large capitalbe required in order
first to adapt the ground for this purpose, the specu-
lation would hardly profit anything, even though he
obtained the sewage for id. a ton.' But with refe-
rence to its peculiar fitness for general farming pur-
poses, he observes, , The full value of sewage, and
of its separate constituents, can only be got out of it
when it is employed on arable land. While, in the
case of a meadow, the whole of that which has been
taken from it the harvest must be replaced in order
to make the yield constant, it is sufficient in the sys-
tem of farmyard manuring to give the farmyard
manure those ingredients in addition which were
taken from the ground in the preceding harvest in
the seeds and meat sold. The component parts of
the straw remain on the farm, and, therefore, need
nothing to replace them. By means of Peruvian
ont ray,
phosphates, he is
fullyguano and phosphates the farmer replaces only a
e contrary,
r to
portionth of these constituents. By means of sewage,
on
reesntaobrle all of
enabled, withthtehme proper
ilisoper
addition
field, and to increase those particular ones which the
field most wants, for • ' •
giving higher and more con-
stant crops. Sewage, as a never failing
source of am-
monia, will prove to him of the value greatest when
the supply of Peruvian guano is at an end,' Turn-
ing from the examination of the report of Baron
Liebig to the scheme of Messrs. Hope and N • apier,
the committee find that they not only propose to
apply the sewage in enormous and wasteful quan-
tities to grass exclusively, for which crop, in their
opinion, it is alone suitable, but that, as their plan
is one of gravitation from first to last, the manure
being applied by flooding the land from open gutters,
it would be impossible by their plan to use it on
arable land and for general farming purposes, as for
such it must of necessity be applied by the hose and
jet, which system those gentlemen entirely repudiate
and hold up to ridicule.
- - - -

The committee having maturely considered the