Delaware gazette. [volume] (Delaware, Ohio) 1855-1886, 1870-12-30
THE GREAT TUNNEL OF MONT
GEMS
Condition OF the work


The works on the tunnel of Mont
Cenis are practically finished, and rem
der communication between France and
Italy rapid and easy. In point of seen
cry, the St. Gems pass has been consld-
cred one of the least interesting of the
Alpine passes. Yet it is not without its
A writer in the Gentleman 5
Magazine for November gives some Gu
nous details. of the pass and tunnel
"The great tunnel through the Alps
passes under the Mont Frejus, about 10
miles west of Mont Cents and the pass
known by that name. 1t is therefore
very incorrectly termed the Mont Gems
tunnel. It cuts through the watershed
of the Rhone and the Po, which in this
part of the Alps is a crest varying from
seven to ten thousand feet above the
sea. Mont Tabor, the highest part of
this crest, is few miles to the west Of
the tunnel, and IS IO,43o feet above the
sea, while the Mont Gents pass, the low
est point, is about the same distance to
the east, and is $500 feet above the sea.
The height of the observatory on the
summit of the ridge over the tunnel is
o,676 feet. The levels of the valleys to
the north and south of this crest or
watershed are respectively 3.6I2 and
4, $50 feet. This difference of level, up
wards of $50 feet, by which the valley
on the south, or Italian side, exceeds the
northern or French side, would seem at
first sight to offer some difficulties in
constructing the tunnel, especially if
much water had been met with. By
taking advantage, however, of the form
of the valley, the railway will be carried
by a zigZag on the mountain to some
hundred feet higher level before entering
the mountain on the French side, reach
ing the entrance Of the tunnel at 4,o46
feet. There thus remains a difference
of 334 feet, which, when distributed
over seven and half miles, is found to
be equivalent to a gradient Of "A feet in
mile, or one in 40.
''The tunnel has not been in course
of actual construction more than twelve
years, but it had been suggested as long
ago as in I84I, in a pamphlet published
at Lyons by Signor Medal, of Bardo-
neche. This pamphlet was brought un-
der the notice of Charles Albert, at that
time King of Sardinia, in whose domin-
ions were included the whole valley of
the Arc, as well as both sides of the
mountain crest The work was thus
from the first exclusively Italian, and
France only became interested in it
when it took possession of Savoy. The
work has been carried on throughout
from both sides by Italian engineers,
according to the terms of the treaty by
which Savoy was ceded to France. The
King referred the matter to the Minister
of the Interior, to make due Inquiries,
and the engineering and physical .ques-
tons involved were submitted to the
consideration and judgment of M. Maus,
a Belgian, who was engineer-in-chief of
the Turin and Genoa Railway, then in
course of construction, and Professor
Sismopda, a very eminent geologist en-
ploy, ne preparation of a geological
map OF dinia, since published. These
two gentlemen, after visiting and exam
lining the whole of the chain between
Mont Gents and Mont Ginevra, reported
favorably of the line selected by M. Me-
dali, which was ultimately adopted. The
matter then went into the hands of 9TH
er engineers, (who have now undertaken
the work for the government, but as on
further investigation and calculation,
based on the rate of progress of similar
works already undertaken, it was esti-
AAAeALA@ IAAf-N eNN A|HA1N - NeAA1 WIN ~
required for the tunneEng, even if no
unexpected difficulties and no accidents
supervened, it was natural enough that
the government should pause before de-
Gliding on a work of such magnitude en-
tirely for the benefit of a future genera
ton. Then came the question whether
by some mechanical Continuance it
might not be possible to accelerate the
4 1TE H.
out of the question to attack the tun-
mel at any point between the two ex-
tremities. In most cases when railway
tunnels are required, a shaft or many
shafts are sunk from the surface, and
the work goes on from each shaft to-
wards both ends, at the same time that
the two ends are being driven. In this
way, by means of two shafts, a tunnel
of three miles mighbbe divided into six
sections of hab8 .nile each, and so in
proportion. But in the case before US,
the height of rock above the tunnel
would be as much as fifteen hundred
feet at a distance Of less than half a
mile on the Piedmont side, and almost
as much on the Savoy side. To sink
Alpine country, and after all leave an
of more than six miles, was not
to be considered for a moment The
whole distance (seven and half miles)
must therefore be pierced from the two
ends. A machine was contrived by
NJ. Maus, which, taking advantage of
the water power abundantly available
on both sides of the mountain, was ex-
pected to reduce the time required for
the work to one fourth but, owing to
the political events of I848, this machine
was never actually put together and
used. After the disturbed times had
passed, and when Italy became a king
dom, the engineers charged with the
execution of the work had perfected the
ingenious and effective machinery that
has since been used for perforating the
rocks. Some time, Of course, elapsed
before operations could be carried on
with steadiness and vigor but for many
years past the tunneling has been going
on, not only steadily but with gradually
increasing certainly and facility. and
the work is now, as we have already
seen, almost in a complete state.
$50 much has now been effected that
the final completion of this great work
is as much a certainty as any engineer
ing operation in progress can we'll be.
It has been carried through from the be-
ginning with great steadiness, and not
one of the numerous drawbacks that
might have interfered to delay its pro-
gress has been experienced. The ma
chinery has been SO far perfected during
The construction that, in spite of the
distance of the power from its
application, the rate of progress has
rather increased than diminished. There
have been no breakages of machinery,
no falling in Of the roof, no rush Of
water. There appear to have been no
strikes of workmen and no failures in
he supply of money and material. 1t
remains only that the two ends should
be happily brought together without
to complete the good fortune
hat has hitherto never failed. Every
orecaution has been taken for this pur-
pose that could be suggested. There
IRE observatories at each end, and one
IN the mountain top, Immediately above
he tunnel but there are great practical