The Cincinnati daily star. [volume] ([Cincinnati, Ohio]) 1875-1880, 1876-09-23
Blowing UD He'll Gate.

DAO"Ah5 Sp AASAA N"OSS
We have heretofore mentioned that
the great engineering achievement of
blowing up He'll Gate is to be consum-
mated tomorrow. The event is regarded
with the utmost interest by the whole
country, and especially by the people
OF the great cities lying about the New
York harbor and the Sound. AS an eX-
ploit in scientific engineering, its re-
suits are watched with the utmost
eagerness by the civil and the military
engineers of the Old World, whose ex-
perience has never yet equaled this in
the magnitude of its special features as
submarine blast. Great preparations
are in progress by hundreds OF thousands
Of people to witness the grand explosion
which is designed TO rend the rock
ribbed reef to atoms; but it is not prob
able that the visible constructions pro-
ceeding from the fearful magazines of
explosives, now quietly nesting within
their stony cradles, will be very i'm
posing. 1t is expected that their gigan-
tic rendings will be expended upon the
granitic resistance beneath the surface
OF the waters.
The New York papers have whole
pages of their columns devoted to
minute description Of this great work;
and from them we shall condense some
Of the more important details.
The location known as "Hell Gate" is
rocky reef at Hallets Point, in the
East River; and which has been a source
OF danger and prolific OF accidents to
vessels ever since the settlement OF New
York by the Dutch. The area occupied
by the reef is only about three acres, but
so lying in the channel as to make it a
serious obstruction to navigation. or
these three acres all but one-fourth OF
an acre has been undermined by tunnels
and galleries running through the solid
rock, leaving columns of sufficient size
and number to sustain the superincum-
bent mass of rock. These tunnels radi-
ate from an open shaft that communi-
Gates with the upper air; which shaft is
entered by a wooden stairway leading
to the bottom thirty-three feet below low
water.
Above the opening Of this shaft, which
is III feet long and 62 feet wide, crane
is swinging, bearing boxes OF dynamite
cartridges, nitro -glycerine, and vulcan
powder sufficient to blow up all New
York if exploded in the open air, and
gently, very gently. letting them down
to the bottom, which is cushioned with
deep covering OF sawdust to prevent
concusson. From the bottom OF this
shaft ten main tunnels radiate, like
spokes from the hub Of a wheel. These
tunnels vary in length from 1856 to 300
feet, and are about IA feet wide, and ay-
erage some IL feet in height. These tun-
nels are intersected by cross-galleries
at intervals of about every 30 feet, thus
leaving the roofs supported by enormous
columns of the native rock.
These massive columns are them
selves again pierced by smaller tunnels,
80 that the whole number of rock pill
lars to the roof are 173, and average
about 10 feet in thickness. The grand
aggregate of tunnels and galleries
amounts to 1925 feet, of which about
two-thiTds are comprised in the larger
tunnels. To excavate these spaces
about $4,000 cubic yards of rock had to
be removed. This great work was COM
menced about seven years ago, though
contemplated long before.
For making suitable lodgment of the
explosives employed to blow up this reef
and demolish its whole rocky structure.
SO that the shattered fragments can be
removed by ordinary appliances, these
rock-columns have been drilled from all
sides, making spaces sufficient for the
insertion of the cartridges for the grand
and final blast. The pillars as well as
the outside walls OF this vast cavern
have bean arranged in what are termed
''battery groups" or these groups there
are 1S4, and each group is drilled for
tweBty charges, making in all $3.50
charges. But beyond these, there are
two and frequently three charges placed