The Sun.
London, England, 1854-05-29 00:00:00

NORTH-DEVON:

_ .
It is intended to open this iine for traffic on Saturday,
July 1. Mr. Brassey, who has taken a lease of the line,
has come to an arrangement with the Bristol and Txetler
Railway Company to work the Line for 12 months.

REPORT OF COMMITTEES ON RAILWAY

INSTITUTION OF CIVIL ENGINEERS.

The paper " On the Casualties of TUnnelling, with
examples," by Mr. W. M. Peniston, M. Inst. C. E.,
was in reality a relation of the difficulties encountered
in the formation of some tunnel headings through chalk
and green sand, under a head of water, at Llolywell, on
the line of the Wilts and Somerset Railway.
The materials had been collected from the author's
diary of the proceedings, and it had'been his intention to
give many more details, as practical examples for the
younger members of the profession, but with access to
the excellent work on tunnelling, by Mr. Simms, it was
feared that the communication might be deemed too
prolix.
It was intended that No. 1 tunnel should have been
constructed in the usual manner, by sinking shafts, and
connecting them by a bottom heading running through
between open cuttings at the north and south ends ;
there were, however, indications from the borings, of
the ground being unfavoui able, the body of the tunnel
being in chalk full of faults, whilst the cuttings at both
ends were in green sand, and copious springs showed
themselves along the line of operations, which were con-
ducted through strata generally dislocated, and not to be
depended on. In sinking the shafts, the waterbrought away
with it such quantities of sand as to create cavities around
and produce serious failures in the timbering which required
to be renenewed and replaced several times. Nu inerous con-
trivances were essayed for overcoming the difficulties,—
gullets were cut at lower levels, in hopes of their draw-
ing off the water, but the tenacity of the soil and the
numerous faults, precluded any chance of their being
useful ; nothing but incessant pumping could therefore
be relied upon ; but the consequence of this was, that the
framing of the shaft sunk bodily, until it was retained by
a hanging kerb and rods from the surface ; then, in spite
of close sheathing planks, a lateral 'settlement occurred,
and amidst' a recurrence of these accidents the shaft was
carried down until the sand and water rose so rapidly
in the bottom, that it was necessary to close it by a
timber platform, through which the water rose to a
certain level, whence it was pumped. Similar difficul-
ties were encountered in the other shafts, enhanced, in
one case, by the frequent recurrence of boulders of sand-
stone, which occasioned much loss of time and inconve-
nience in extracting them, and left large cavities behind
the sheathing. .The quantity of water also increased so
much, that the briefest delay_ in pumping, obliged the
pen to leave the headings.
At length, it being observed, that the dip of the sand-
rook, which was the water-bearing stratum, was in such
a direction as to induce the inference, that it might be
used to convey the Water away by having it tapped
at a lower level, the attempt was made, and was attended
with success. In the'subsequent extension of the open
cuttings, the numerous vertical faults were' shown to
have been, in a great degree, the cause of the
.slips in
the shafts.

In consequence of obseriations on the saturated strata,
vwas determined to try the effect of a syphon, which
as accordingly laid down ; it wag formed of cast-iron
pipes, 6 inches diameter, the short leg dipping into a
hole at the bottom of one of the shafts, whilst the long
leg extended through the crown heading and terminated
in a cistern in the north cutting. By means of a hand-
pump, at the upper bend, the air was exhausted, and
the action was so perfect as to drain the blocks of sand
enable the headings to be completed.
Accounts were given of the numerous ingenious con-
trivances resorted to for overcoming difficulties, and also
of the effects of the drainage upon the springs and wells
in the neighbourhood. The various machines and de-
vices employed were described in. connection with all the
tunnels ; in fact the paper was, as it professed to be, a
detail of the casualties of tunnelling, under circumstances
of considerable difficulty, -and it was well illustrated by
a series of diagrams, showing the works in all stages of
of their progress.
It was again announced from the chair that the Presi-
dent's annual convprsazione
.would be held on Tuesday
evening, May 30th, when the co-operation of the mem-
bers and visitors was requested, in order that a collec-
tion of models of engineering construction, and of speci-
linens of works of art, worthy of the institution, might
be made.
At the monthly ballot, the fbllowing candidates were
duly elected :—Mr. J. Quick, as a member ; Messrs. T.
Bell, D. Chadwick, J. Falshaiv, W. Reid, and-S. E.
Rosser, as associates.