, 1880-05-24
The Greatest Tunnel in the World.

The brief cable message which an
nounced last week the piercing of the
ST. Gothard tunnel, told of the. success
full completion of the greatest task ever
undertaken by modern engineering.
The tunnel is rather more than seven
and half miles long, OF three miles
longer than the Hoosaac tunnel. The
whole cost is said to have been not less
than SIS 100000. The work was pro
jected as far back as 1850, and ten years
later, the suggestion began to take prac-
tical shape, but it was not until 1872
that company was formed and con-
tract awarded. Since that time the
work has gone steadily on.
The contract for the work was
awarded to NJ. Louis Favre, whose
skill and energy proved to be great
enough to surmount all obstacles. He
literally sacrificed his life to the work,
and died in the tunnel last July The
tunnel for about two-thirds of its
length passes through solid rock, of
granite, gneiss and hornblende. Part
of the way is limestone, gypsum and
schist. One of the great difficulties of
the work was that blast would often
open spring which would deluge the
tunnel for hours, and perhaps for days.
One of these springs discharged water
at the rate of 42O gallons a minute, an
other 1000 gallons, and one as high as
1900 gallons. The method of doing
the work is thus described:
The headings used were about eight
feet square, giving frontal areas of
sixty seven square feet on which the
perforating machines operated. In
hard rock from twenty-four to twenty
six holes were bored on each face.
They were charged with dynamite,
which was made up in cartridges of
from one and half to four pounds.
The perforating machines employed in
the heading are six in number, and are
mounted on a truck set on line of
rails. The process of 5oring lasted
from two and half to three hours,
and while the last holes were being
bored the process of charging was com
menced. The carriage and machinery
was moved ninety feet off, and turned
into siding in the widened part of the
tunnel. The three central holes con-
verged to a point at their furthest ex-
tremity. They were fired first, and
made a conical cavity. Then the other
holes were charged and fired, and they
expanded the rift to the full size of the
heading. The debris is then removed,
and the same operation is repeated.
The temperature Of the air in the tun-
mel was found to be always higher
than that without. It steadily increased
as the excavation proceeded. On
the first day it rose from 50 degrees
Fahrenheit to So degrees, while the air
outside remained 81 degrees. The
average temperature further in was
found to be over 20 degeees, while the
rock was also much warmer than the
surrounding atmosphere. Large bell
exhausters were erected at each end of
the tunnel for the removal of atmos-
pheric impurities, although artificial
ventilation was not needed until the
boring was l 900 meters deep. About
five million cubic feet of compressed
air were forced into the excavation
each day from either end, and an ex-
hauster, capable of extracting 16 500
cubic feet per minute, has been pro
vided at each.
Part of the work had to be done by
haaaboring, and but p: feet day
could be gained at this, while machine
boring gave progress of seven feet q
day. When the tunnel is completed |
in accordance with the provisions of a
the contract, it will be of horseshoe |
form, and will be 1868 feet high by
Il, 50 feet wide at the level of the Sleep |
ers, and 23.24 feet at the springing of |
the arch, which will be about 611z feet
above the sleepcrs. The arch will be a
complete semicircle of 4smeters radius,
the sides being curved to a radius of
80 Is feet. The floor when OF solid
rock will be slightly troughed. When
the tunnel passes through solid rock it
Is to be cut to the exact section without
any masonry; when assures occur, en-
arch will be used varying III form ac-
cOrdlng to clrcIms stances. When
loose rock is encountered, the tunnel
will be lined with asher stone ma
sonry according to the figures given
above. 4 culver. 32S feet square will
run under the floor of the tunnel
its length.
The communication between France
and Italy will now offer as little OBJ
struction as that between France and
Holland. So far as commerce and
travel are concerned, it is as though
the Alps had been removed and cast
into the sea. And thus another is
added to the triumphs OF modern engi-
leering.
A paragraph went the rounds of the
English newspapers last winter about
a pheasant having been shot that
lad wooden leg. Nov the sequel
IS being published. It t
that London surgeon, t i
lay in tie country, for it
caught by one leg in Q