The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1880-07-29
BORING THE TUNNEL.
How the workmen Dig their Way Through
the Mad and are Protected from Danger
Wonders Of Compressed Air.
From, the Mese York Times.


Piles of boiler-iron plates, a heap o
bricks and masons' materials, and col
lection of low sheds with an immense
smoke-stack towering above them, MARI
the spot at the foot Of Fifteenth street
Jersey City, where the Hudson iTunne
Railroad Company haye :commenced the
mighty work Of tuanelling the North
River. The work is we'll under way, ano
is being pushed forward day and night
with no iet.up on Sundays or holidays
Already 300 feet of the tunnel have been
completed, 200 Of which are under the
the river itself, and within q months
time the workmen. will be adding
to its length at the rate of between
four and five feet every twenty.foul
hours.
The method of building the tunnel is
different, it is claimed, from anything
ever before attempted. The! principle
is adopted of using compressed all
to exclude the water, evaporate the
moisture of the silt, so that the lat
ter, by being thus dried, can be easily
handled at the heading, and is rendered
less liable to cave in, and to aid in up
holding the iron and brick work after
they are placedin position. Col. Haskin.
has secured q patent in connection with
the application of this principle, under
which the tunnelling is being done. The
land in this vicinity is largely of einders,
which have been filed in, sand tits SO
porous that when the tunnel was first
commenced there was q constant escape
of the air which was forced into the ex-
cayation. This was remedied by burying
large sheets of canvas several feet below
the surface Of the ground. The lower
the tunnel went, however, the more
compact the filling became, and the less
annoyance was experienced from this
source. Now that the silt has been PEN
etrated, this difficulty no longer exists.
The pressure of the compressed air now
used in the tunnel is about twenty pounds
to the square inch. The two air COM
pressors are kept running day and night.
They pump the air into the air-reservoir,
which is of tough boiler-iron, cylindrical
in shape and has diameter of five feet
eleven inches. A'gauge at its side always
indicates the pressure of the air in the
tunnel. From the reservoir the air is
pumped into the tunnel through the air.
lock. Upon this supply Of pure air and
a careful regulation Of, its pressure the
lives of the workmen, and the success of
the work depend, and constant eye is
kept upon the movements of the gauge
fiuger as it balances itself unsteadily over
the dial. The tunnel was gradually
pushed downward from the. air-lock until
the proper level was reached, instead of
being commenced at the bottom of the
shaft and continued on the required level.
This was temporary device, and after
the work had been thus prosecuted for
distance of 300 feet the heading was bulk
headed, and the workmen, turning in
their tracks, began to dig toward the
shaft and to clear away distractions in
this direction. Here the grand arch at
the mouth of the tunnel will be built.
Its width will be 80 feet and its height
80 feet. Upon;this work the men are
now engaged.
There will be two tunnels thrown
across the river, each being l8 feet wide
and 16 feet in the clear when completed.
They adjoin one another, but will be sep
arate and distinct pieces of workmanship,
uniting, however, under the grand arches
at the working-shaft on either side of the
river. AsingIe track will be laid in each,
and, ,as one Of themywill always be, used
IN going in and the other in coming out Of
the New York depot, collisions can never
occur. The approaches to the tunnel
on both sides of the river will be 26 feet
wide and Is feet high in the clear, and
their walls are to be of the best hard
burned brick laid in hydraulic cement.
In this city the tracks will not be less
than Is feet below the surface, and at no
point, when the tunnel is completed will
the surface be disturbed in the streets
except for entrance to and egress from
the underground depot.
In shape these twin tunnels will be
nearly round. Their shells are cylinders
made of boiler iron about % feetin height
and 20 feet in breadth. They are made
in sections which are welded together,
and the completed shells are pushed
ahead as fast as the excavations are made.
The iron of one ofthese cylinders is 4-inch
In thickness. The sections or plates are
2 feet 6 inches in width. Some of them
are feet and others 6 feet in length.
On each of their four sides are flanges
81 inches in width, through which the
plate is bolted to every one of the plates
around it. The joints are broken as the
plates are wedged together to give addi-
tional strength to the cylinder. AS fast
as the cylinder is advanced the masons
follow, and line it with wall of hard.
burned brick two feet thick in hard cement,
As this wall extends completely around
the interior it presents the form of an
arch against any outside pressure, wheth.
er vertical or lateral. Four classes Of
men are employed in building the tunnel
miners, welders, laborers and masons
At the heading the miners advance with
pick and shovel, the welders bring to-
gether the iron sections, the laborers dis
pose of the diggings, and the masons
throw up their wall.