St. Johnsbury Caledonian. [volume] (St. Johnsbury, Vt.) 1867-1919, 1871-02-10
4 Great Work Completed.

For the last dozen years we have oc-
casionally observed brief illusions TO a
magnificent cntcrprise-its progress and
the probable time Of its complction.-
This was the opening of a railway track
through Mont Gents, to connect Italy
with France-rcducing the distance from
80 miles-the length of the road over
the mountain built by Napoleon in 1905
to about s miles. The highest point
of the mountain passed by the highway,
is 5,4O0 feet. The tunnel, just complrt-
ed passes under the mountain at one
point, 900 feet abovt the level OF the
sea.
The size Of the bore is, in height, %
feet, : inches, and the width, at the base.
% feet, 3 inches. The tunnel is in the
form of n segment of Il cylinder, the bot
tom being level. The enterprise was be-
gun in 1SJ1-thc French commencing
from their side, and the Italians from
thcirs-and when the parties met, the
French had made IN annual progress Of
a fraction over 81 metres, Ga metre is
81 feet and the Italians Il fraction over
53-thc whole distance being II, 220
metres.
Until 1868 the common hand drill
was used for pcrforating the rock, and
powder rs the explosive agent. AT the
rate Of progress made by this mode it
would have required 80 years time TO
complete the tunnel. The Italian cngi-
neers set about invcnling something more
efficient, and after some experimenting
they succeeded, and their machine was
put into use at both ends of tie tunnel.
1t is of curious construction and Of sin
gular efficiency. 1t is described as fol-
lows:
GA machine was put into operation
which could stand outside by one of the
streams that came down from the noun
tains, AMI with its aid force the air
through long tubes to the drilling appa-
ratus This latter is Il machine which
works in galley nine feet square, and
carries Il large number OF pcrlorators.
each OF which borcs 4 separate hole in
the rock. by the COMPRISING machine
the air is forced into Il reservoir, and
thence it passes through flexible pipes to
the cylinders containing the drills of the
per'orating machines. BY the opening
Of Il valve each drill Is forced against the
face Of the rock with IL force of about
200 pounds, turned slightly, and with
drawn. Two hundred of the blows are
given every minute with each drill, and
when holes Of the required depth have
been bored, the air is turned of, AMI the
machine withdrawn Il short distance.
The holes are bored in such way rs to
converge slightly toward each other, so
that every blast will bring down con-
siderable mass of rock. At first, powder
was used in the blasting, but there were
many obvious objections to this As soon
. as any considerable progress had been
made, and subsequently, gun-cotton was
tried. This was aftcrward displaced by
the use of ntro-glyccrinc. The rate of
progress has varied, of course, with the
hardness of the rock, and has been from
one and Il half TO three feet per day."
In the work Of tunncling the IIoosac
mountain, in western Massachusetts.
shafts have been sunk from time TO time.
TO afford air and light, if not for other
purposes. No shafts have been sunk in
the Mont Gents work, but the workmcn
employed incidental appliances, dcscrib-
ell as "a gas-housc, miniature water
WORKS. and machinery for supplying their
own lungs with air as well as those of
the perforating machinery"
1t will require several months 70 Law
the track through this tunnel Of c;cI,,
miles, and get it ready for the use Of ,bo
public. The work has been executed Inv
means Of Legislative appropriations from
both the French and Italian governments.
and costing, from 1877 to the close of
the year 1858, As! millions of francs, or
nearly ten million dollars. During the
year lSGS, j millions were expended,
ana baslng the calculation for the last
Two years upon the expenditure for 1868,
would give total Of G3! million francs.
bonaparte's road through the pass of the
mountain cost millions Of francs. This
work OF tunneling the AIps-thc bcgin-
ming upon two sides, the working inward
ly, and meeting exactly-is triumph of