The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1880-07-20
New York q'iaes.l

New YORK IinesJ
piles OF boiIer-iron plates, beap OF
hrIcks and masons' materials, and co'iec-
tion Of low sheds with an immense smoke.
stack towering shove them, marx tue spot
- shs foot OF Fifteenth street, jersey City,
~hcrr the Hudson Tunnel Railroad Com
rsnv have commenced the mighty work OF
tunnelljnr the North river. The work Is
we'll under way, and IL being pushed Tor
ward day and night, with no let.up on sum
dsys or holidays. Already 300 feet OF the
tunnel have been completed. 200 OF which
are under the river itself, aud within
months time the workmen VIII be adding
70 ia length at the rate OF between TOUR anu
i've feet every tweniy-four hours.
The method OF building the tunnel Is dif-
ferer,i. IL Il claimed, from anything ever be-
fore attempted. Tue principle Is adopted OF
usInV compressed air to exclude the wafer,
evanarate the moisture OF the silt, so that
the latter, by being thus dried. can be easily
handled at the heading, and Is rendered less
liable 10 cave In, and to aid In UNFOLDING
the IRON and brick-work after they are
plsced In position. Colonel Haskfns has
securcd patent in connection Win ine APP
plicsti0n OF this principle, under when ihe
fuunellipg is being done. The land 10 inns
vicinity IL largely OF cinders, which have
",
the tunnel was first commenced there
was a constant escape Of the air which was
forced into the excavation. This was
remedied bv burying large sheets Of cam
vas several feet below the surface OF the
ground. The lower the tunnel went, how
ever, the more compact the filling became.
and the less ANNOYANCE was experienced
from this source. Now that the silt has
been penetrated, this difficulty no longer
exists. The pressure OF the compressed
air now used In the tunnel is about twenty
pounds 10 the square inch. The two air
eompressors are kept running day and
night. They pump the air into the air-re-
seryoir, which is Of tough b0iler-iron, cy.
Iindrical in shape, and has diameter OF 5
feet IL 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
careful regulation OF its pressure the lives
Of the wol kmen and the success OF the work
depend, and a constant eye is kept upon the
movements Of the gauge.iDger As it balances
Itself unsteadily over the dial. The tunnel
was gradually pushed downward from the
ait.l 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 800 feet the heading wa
bulkheaded. and the workmcD, turning in
their tracks, began to dig toward the SHAFT
and 10 clear array distractions IL this dIrec-
ton. Here the grand aIch 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.
Properly speaking, there will be two tun-
nels thrown across the river, each being Is
feet wide and 16 feet in the clear when com.
pleted. They adioin one another, but Will
be separate and distinct pieces OF workman
ship. uniting, however, under The grand
arches at the working shaft on either side
of the river. A single tack will be laid in
each, and, as one OF them will always be
used In going in and the other in coming
out OF the New York deI0t, collisions can
never occur. The approaches to the tunnel
ON both sides OF the river will be rs feet
wide and "a 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
bolIer-iron, about % feet in height ADD 20
feet i'm breadth. They are made in sections
which are welded together, and the COM
pIeted shells are pushed ahead as fast as the
excavations are made. The iron OF one OF
these cylinders il 1 inch in thickness. The
sections or plates are 2 feet inches in
width. Some Of them are feet and others
6 feet in length. On each OF their four sides
are fanges q inches In width, through
which the plate is bolted to every one OF the
plates around it. The Joints ATE broken as the
plates are welded together TO give additional
strength to The cylinder. AS fast as the
cylinder is advanced the masons follow,
and line il with wall OF harburned brick
2 feet in thickness laid in bard cement.
AS this wall extends completely around the
interior ii presents the form OF an arch
against any outside pressure. whether
vertical or lateral. Four classes OF men
are employed In building the tunnel
miners, welders, Iaborers, and masoOs. At
the heading the miners advance with pick
and shovel, the weldcrs bring together The
iron sections, the laborers dispose OF the
diggings, and the masons throw up their
brick wall.