The Sun.
London, England, 1860-02-16 00:00:00

.NOVEL ENGINEERING OPERATION.

A very novel engineering operation was described
at a reeent meeting of the Institution of Civil Engi-
neers, by Mr. F. C. Stileman, one of its members.
This was an enlargement of the Lindal tunnel, on
the Furness Railway, which as a single line, was com-
pleted and opened in June, 1851. The facilities af-
forded by this railway having led to a great develop-
ment of the mineral traffic of the district, en Act of
Parliament was obtained for the formation of the
Ulverston and Lancaster railway, thus completing
the chain of coast railways between Lancaster and.
Whitehaven, and so onwards to Carlisle. It then be-
came evident that a single line would be insufficient

to accommodate the traffic. Consequently, in August,
1854, it was decided to widen the line, and to en-
large the Lindal tunnel. The tunnel was increased
in width equally on each side of the existing single-
line tunnel, the level of the rails remaining the same.
Before the works of enlargement were commenced,
the contractor, Mr. Tredwell, suggested that another
single or twin tunnel, parallel with the existing one,
could be constructed with less risk; and he offered to
complete it for the same sum, notwithstanding the
additional excavation necessary in the approaches.
This proposition had not been favourably entertained,
because there was no precedent for such a work, and
because it was known that there were many and grave
disadvantages in working a single-line tunnel. From
its limited area, the atmosphere in such a tunnel after
the passing of heavy trains becomes so charged
with steam and sulphurous vapour, that the plate-
layers cannot work for any length of time continu-
ously, and hence there is a difficulty in properly
lifting and packing the permanent way. Again, the
condensation of the steam upon the rails in single-
line tunnels practically increases the expense of
working. From the commencement of the Lindal

tunnel works in June, 1855, to their completion in
Nov., 1856, nearly seven thousand five hundred
passenger trains, conveying one hundred and
twelve thousand passengers, and two thousand
one hundred goods trains, carrying two hundred
and five thousand tons of minerals, &c., ex-
clusive of light engines, passed through the tunnel,
without the slightest casualty to either description
of train, or any accident even of the most trivial
character to any individual. A special code of rules
was arranged for working the traffic, and for
watching and signalling every train. The stations
at each end of the tunnel were in telegraphic com-
munication, and there were semaphore signals at
each entranee, connected by an endless wire.
The wire was fastened to wheels at various
points, having cranks outside the trough
in which it was enclosed. A signalman
whose duty it was to remain in the tunnel, could
by means of a portable lever, lower both semaphore
signals simultaneously. As a precautionary rim-,
sure, the signalman sounded a large gong on being
informed by the telegraph that a train was ap-
proaching; and it was not until he had satisfied
himself that no impediment existed to the passage
of the train, that he lowered the signals, and thus
sanctioned the engine drivers to proceed.—
Mechanics' Magazine.

21I1S DAY'S MA RKETS.

CORN EXCHANGE.

IMPERIAL WEEKLY AVERAGES. - Wheat, 43s 6d ;
barley, 34s lld ; oats, 21s lld ; rye, 29s 9d ; beans, 38s
4d; and peas, 36a Od.

THE SIX. WEEKS' AVERAGES. Wheat, 43s 10d ;
barley, 34s 7d ; oats, 21s 4d ; rye, 31s lld ; beans, 38s 6d ;
peas, 36s 6d.

ENGLISH ORLIN SOLD LAST WEEK.—Wheat, 111,617;
barley, 77,063 ; oats, 17,391 ; rye, 131; beans, 6,715 , peas,
2,085 quarters.