The Elk County advocate. [volume] (Ridgway, Pa.) 1868-1883, 1875-11-04
UNDER THE WATER AND ROCKS.
Condition of the Submarine Operations ut
HurI Gate, in New York Ha, Dor.

Condition of the Submarine Operations ut
HurI Gate, in New York Ha,bor.
A few rods above the village of As
toria, on the East river, N. Y, is Hal
lett's Point, where extensive operations
looking to the improvement of the chan
mel have been going on for the past six
years. The operations consist III under
mining the bed rock of the river for o
considerable distance by system of
tunnels, or headings" as engineers
term them, leaving columns to support
the roof until the charges are ready to
be fired. As no external evidence of the
character of the work exists, but few
persons are aware of the great labor in
volved. No less than two and half
acres have been tunneled under, with an
aggregate length of tunnel of one and
one-half miles; the width and height
being respectively eight feet and twelve
feet. A plan of these excavations ap-
pears like an irregular checker board ;
the black squares representing the piers
which still remain holding the roof.
These will be removed in the final blast,
which is expected to throw down the
whole rock bed involved, and probably
much subiacent. All of the headings
have been driven and the only remaining
task is to bore the piers for the admis-
sion of charges. The roof is also being
bored in each chamber with holes lead
ing diagonally; in these nitro-glycerine,
or its equivalent, is to be placed and the
whole exploded by one battery.
To insure certain ignition of this i'm
mense quantity of explosive material,
q oha, nf oh ain nI q
each, every charge connects with the
others by system of pipes, or iron
tubes, probably half an inch in diameter,
filed with explosive in quantities to al
most constitute charge of itself. The
work is system of gigantic pockets cut
in the solid rock charged withexplosive,
connected intimately with fuses, and to
be fired by one battery at the proper
time. "
The greatest depth of water over the
works is twenty six feet ; the greatest
thickness of the roof eighteen feet, and
the longest heading 315 feet. All the
bodies have been bored by drills driven
by compressed air, and about 1000 holes
vet remain to be made. The leakage
through the roof amounts to 500 gallons
per minute. This is all led into one ol
the headings, which also communicates
with a we'll at the end of the tunnel
whence it is removed by pumps.
The successful termination of this
work will straighten the shore line ma
terially, add much to the width of the
channel, and alter some of the currents
which set so strongly now at food ant
ebb tide rs to greatly endanger com
merce.
At this place the tide sweeps through
With velocity of nine knots, or ovel
ten miles, per hour, and as the channe
is only a few hundred feet wide ant
hedged about with rocks above and be
low, it is easy to see that navigators will
have reason to pray for the success o
the undertaking.
The cost of the work up to the pres
ent time has been about $750,000, anc
it will require at least $500, 900 more t.
complete it.
1t is expected that the final operation
that of firing the charges, will transpir
some time early in the summer of 1876
II will be an event we'll worth witnessing
The effect of 10000 pounds of glycerin
fired at once would create small earth
quake if in one mass, but it is stated b.
Capt. William H. Heuer, of the Unite
States engineers, that subdividing thi
quantity into numerous small charge
very greatly lessons the shock.