The Sun.
London, England, 1862-07-25 00:00:00

THE SUBTERRANEAN RAILTVAY.

The time by which it was hoped to open the first
length of this important branch of metropolitan
communication for traffic from the Victoria ter-
minus to Paddington has already been overpassed
by several weeks, and yet a further postponement
is anticipated to the end of September or begin-
ning of October. The first estimated date of com-
pletion was undoubtedly premature, and due to
the not uncommon cause of contractors being
over-sanguine as to the time required to finish
their labour. Apparently the line could not,
under the most favourable circumstances,
have been opened before this month at soonest,
and why it cannot be ready then is due indirectly
to the unexpected "caving in" of Fleet ditch, the
largest, foulest, and worst-built of all our London
sewers. We say that the delay is due indirectly to
this cause, for the amount of mischief which the
bursting of the sewer was alleged to have
inflicted on the railroad has been somewhat exag-

Berated. The whole amount of damage it caused
to the line consisted in undermining 120 feet of the
retaining wall near the Victoria station, and this
can be replaced at a cost of less than £7OO. The
delay has arisen in the first place from the com-
pany being unable to resume their works until the
Fleet ditch was diverted into a new channel, which
had to be cut, and its sides secured with powerful
shores, and, secondly, because the company wished
things to remain in statu quo till the eminent engi-
neers they called in had finished their inspection,
with a view of deciding the rather difficult ques-
tion of whether the sewer had collapsed from
gradual decay and bad construction, or had been
accelerated to its fate by the vicinity of the railway
works.

In the construction of such a peculiar tunnel as
the Subterranean Railway, running under the very
heart of the metropolis, of course every yard had its
own peculiar difficulties. The whose length now
completed is about 31 miles. From west to east
the average slope downwards of the entire line is
one in 100 feet, but after entering the City it again
rises, though there is no steeper gradient through-
out than that we have mentioned. The sharpest
curve is of 200 yards radius. There are not more
than 1,200 yards of straight line in the whole
length, and the rails are sometimes at a depth be-
neath the earth of not less than 54 feet. Such a
line, of course, passes through almost all the kinds
of subsoil to be found in London—gravel, clay,
rubbish, and sand, and each soil required certain
adaptations in the strength of the tunnel that
penetrated it. The span of the arch of the
tunnel is 281 feet, its form is generally elliptical,
and its height 17 feet. This is the general
style of the structure where there are no pecu-
liar difficulties to surmount. Parts of this kind
have six rings of brickwork, though railway
arches of 7 feet greater span are never built with
more than five. In other places, however, where
there is great superincumbent pressure to resist, the
form of the arch is altered to give it greater strength
and to take the crown to a height of 19 feet. At
no part are the foundations of the brickwork taken
less than from four to five feet into the solid ground
below the rails; and, where the close vicinity of
very heavy buildings rendered extra strength neces-
sary, the whole has been driven like a shaft, and is
a solid ring of massive brick work above and below.
In fact, in all parts of the structure the most zealous
care has been taken to insure its being everywhere
greatly in excess of the strength required, and all
the outer sides of the arches have been filled in with
beds of solid concrete, covered over with asphalte to

keep all water-tight. The easier portions were con-
structed in 12 'feet lengths at the rate of 72 feet a
week—quicker than any work of the kind has ever
been accomplished ; but when passing near churches
or other heavy buildings a regular shaft had, as we
have said, to be driven by skilled miners in four-
feet lengths, and from the great care requisite at
these parts the works advanced but slowly. Of course 1
there were all sorts of other difficulties in the way of
sewers, gas pipes, water mains, with exceedingly
abundant springs of good water breaking out at
unexpected and most inconvenient places, and one
of the most difficult of all the difficulties was caused
by Fleet ditch sewer. This, the foullest of all those
noisome arteries that drain this city of its daily
filth, could not be interfered with, and it somehow
always crossed and recrossed the line precisely at
those points where the works were most difficult
and where it seemed almost impossible to take the
tunnel under it at all.
Where the junctions have been effected at King's
cross it was necessary at the point where the switch
rails joined to widen the tunnel, and at these parts
make it, in fact, open out like the mouth of a trum-
pet. This was a most difficult operation ever
attempted either in tunnelling or brickwork, but
Mr. Fowler has surmounted all the obstacles in a
masterly manner. What made it more difficult was
the most critical part the Fleet ditch sewer crossed
it right through the crown of the tunnel arch. As
the sewer could not be moved, the obstacle was met
by carrying it across, slung, as it were, in a strong
cast-iron trough, and there it now hangs, peering
point it runs
through the brickwork like a colossal main, and
with all beneath it as dry and sweet-smelling as if
Fleet ditch were 100 miles away. Again, at an-
other very difficult part—at Frederick-street—it
actually rests upon the tunnel enclosed beneath, as
Victoria-street at King' • • • -
point it is
e-cross, in a similar iron tube. From this
almost parallel with the tunnel at vary-
ing
distances,tthe nearest point of approach being
one,, where it has fallen in, and at this
30 feet of it
which is
12 or 13 feet from the ope❑
thinein 1 mislfuelaeypdteerinfeourmtbheen
ttermo
roadway.
month,
station.uotntit Here,
suddpart, on the 15th of last
gave in, taking down
with it the whole piece
to a thickness of some 16
been carefully cut out. The tseleanly as if it had
passage, at rubbish, of course, in
the waters kept
6tantly blocked the