The Sun.
London, England, 1861-11-30 00:00:00

it aduall3- requires. Thu , even the lightest
parts of the tunnel have six rings of brickwork,
though railway aiehes or seven feet greater span

are never built with more than five. The outer
sides of the arches also are filled in with solid beds
of concrete, and the whole covered over with a

layer of asphalte to keep it water-tight. In fact,
the tunnel has been formed on what engineers call
the " cut and cover" principle ; that is, the ground
has been opened to the base of the intended tunnel,
the, tunnel built, covered with concrete, and

asphalte anti filled in again with earth and the
roadway paved over as before. On this plan and
working in 12ft. lengths the tunnel has actually

been constructed at the rate of 72ft. a week, quicker

than any work of the kind has ever yet been no-

complished. It I►as not all, however, been knocked

off at this rapid rate. Passing near churches and
heavy buildings the tunnel has been regularly
driven in four feet lengths by skilled miners; and
such portions, being conducted with the most zea-
lous care, have advanced but slowly. At the
western extremity, where the soil was a fine gravel,
the works were at one time greatly impeded by the
water, which in that district is abundant every-
where at about 14ft. from the surface. This it was
useless to try pumping our, as the pumps brought
up sand and gravel as well as water, and would,
had the attempt been persevered in, have
brought up the very foundation of the surround-
ing houses also. It was necessary at last to
mako regular drains into the low-level sewers in
order to keep the works free. Through the gravel
and through the London clay the labour has been
very easy, but in parts where there was light loose,
sandy soil a great deal of difficulty was experienced.
All the really difficult parts have now, however, been
surmounted, and the tunnel built in the most solid
manner. The lines of rails are laid through
many lengths, each line being double gauge, in-
tended for both the broad and narrow traffic. Where
the junctions have been effected at Paddington
and 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 like the mouth of a
trumpet. This was the most difficult operation ever
attempted in either tunnelling or brickwork, but
Mr. Fowler has surmounted all the obstacles in a
masterly manner. What made the work at King's-
cross more difficult than all was that at precisely
the most difficult part of all the junctions the great
Fleet Ditch sewer crossed it right through the crown
of the tunnel arch. As the sewer of course could
not be disturbed, the obstacle was met by carrying
it across, slung, as it were, in a powerful cast-iron
trough, and there it now hangs, peering through
the brickwork like a colossal main, and with all
beneath it as dry and sweet-smelling as if Fleet
Ditch—that fullest and foulest of all London's
sewers—were 100 miles away. It is but justice to
Mr. Jay, the contractor for all this end of the
works from Euston-square, to say that he has
accomplished all the designs in the most massive
and careful manner, and that in fact the works here
are regarded among engineers as positive models
of what contract labour should be. The stations
along the lino which we have already enumerated
will, all but two, be open-air stations, and even those
that are to be underground will be amply lit by
daylight coming through apertures in the roof of
the arch. But one of the greatest difficulties of all
the many that had to be overcome consisted in con-
structing an engine that should be at once of great
power and speed, capable of consuming its own
smoke, and above all to give off no steam. Ordinary
engines passing through tunnels so completely en•
closed would in a very short time fill them with
such a mixture of steam and smoke as would be
very nearly suffocating, would make signals almost
useless, and in short render the traffic not only dis-
agreeable but dangerous. To avoid all these com-
plicated evils Mr. Fowler has invented an engine
which, while in the open air, works like a common
locomotive, but when in the tunnel consumes its
own smoke, or rather makes none, and by condens-
ing its own steam gives off not a particle of vapour.
On Thursday last Mr. Wilkinson, the chairman
of the company, with Mr. Alderman Rose, Mr.
Pearson, and a number of gentlemen connected
with the company, the City Corporation, and the
Board of Works, were invited to Paddington to
witness a trial of this engine. They were received
by Mr. T. M. Johnson, the resident engineer, under
whose personal superintendence all the works of the
line have been effected. Tho engine (which was of
the broad gauge) was duly examined and admired,
though, truth to say, there is nothing particularly
attractive in its external appearance. The whole
party then mounted trucks provided for the occa-
sion, and the engine took the train along the first
tunnel to the open station in course of building in
the Edgware-road. As long as the engine remained
in the open air at Paddington it had fizzed and sim-
mered like any other locomotive; but the instant it
entered the tunnel it condensed its steam, and
scarcely a mark of vapour was perceptible, while
from the flues into the smoke box being damped,
not the least smell of smoke was given off. As upon
the success of this engine the successful working of
the line depends, the result of the experiment was
watched with a good deal of anxiety. It, however,
was perfectly satisfactory, and not even the most
distant lamps in the long vista down the sides of the
tunnel were dimmed in the slightest degree—in
short, nothing could have been more entirely com-
plete and satisfactory. Having gone through the
tunnel the engine returned down the same track,
and when in the centre of the tunnel, to show the
difference, the engine was allowed to work upon the
usual plan, and in a few instants the whole place
was full of vapour, which was so thick that even
when the visitors returned through for the third
time the lamps were still scarcely visible.
The party were then invited to leave the train
and to walk along the line as far as the Great
Northern station at King's-cross. In some parts of
this route, where the tunnelling is still going on,
the way was dark, sometimes difficult, and always
dirty. Where the works were complete and the rails
laid, the whole aspect of the tunnel lit with gas
was light, warm, and cheerful. In at most three or
four months more our readers will have an oppor-
tunity of judging of this wonderful work for them-
selves, and we think a single trip will suffice, even
with the most fastidious, to upset all preconceived
ideas as to the discomforts of subterranean railways
in London. The through trains from cast to west,
and rice versa, will, we believe, be arranged to start
every 10 minutes, to accomplish the distance from
end to end in 13 minutes, at a rate of fares which it
is said will compete with those of the cheapest
omnibuses. If this is so the line ought to prove
remunerative to the shareholders, though whether
it is so or not it must be an immense convenience to
he public.