The Republican journal. [volume] (Belfast, Me.) 1829-current, 1875-10-28
The Coming Great Blast.

The work of deepening and charging
the East River channel at Hallett's Point,
He'll Gate, New York Harbor, is fast APP
preaching completion, and it is now at
tracing the special attention OF engineers
and men of science throughout the coun-
try Owing to the peculiar formation of
the rock at Hallett's Point, together with
the narrowness of the present channel
and the almost uninterrupted passage of
vessels, the work has been done under
many disadvantageous circumstances. AZ
ter tedious work Of nearly six years the
task of excavating has at last been com
pleted, and the secondary work of pre-
pairing Tor the grand blast is now going
on. Inasmuch as the explosive power to
be used on the final blast will be about
fifty thousand pounds of tro-glycerine,
or about eight times as much as has ever
been simultaneously discharged before,
much interest and not a little anxiety is
being manifested in the result.
The work, which is being superintend-
ed by Mr.. William II. Heuer, was begun
in 1869, and the amount expended on it
has been roughly estimated at about $780,
900. The excavation extends under -
acres of gneiss rock, vertically stratified
and running in northeasterly and south
westerly direction. Starting from main
shaft "a feet below mean low water, ten
main headings, sloping down to 50 feet
below mean low water, have been extend
ed out to an average length of 25O feet
each. The height OF these main headings
varies from s to % feet each, with an
average width of IA feet. From the main
headings intermediate headings have been
cut, and at uniform distances circular gal
leries have also been cut across the head
ings, thus forminga series of piers at their
point Of intersection. There are in all 173
piers, which form the entire support of
the roof and of the water above it. and
which also separate the Al headings and
10 galleries. 1t is estimated that the en-
tire amount of rock TO be broken by the
proposed blast Will aggregate about 49,,
900 cubic yards. Since the completion of
the excavation and the bringing down of
the piers to a uniform size, the work of
boring holes in the roof and sides has
been begun. For this purpose six Bur
leigh drills are used daily, boring about
twenty-one holes in twenty-four hours.
The working force now engaged in this
work is 12O men, divided into three gangs,
each of which work eight consecutive
hours, in order that there may be 10 ces-
sation
Captain Heuer expects to complete the
drilling about the last Of January, when
the important work OF charging each hole
will be begun. This will have to be done
by experienced Workmen, with great care,
and will occupy about two months. The
explosives will be placed in iron tubes,
each of which will have direct battery
connection, besides being connected with
the adjacent holes by the means of series
of small tubes filled with nltro-glycerine.
This precautionary measure will be taken
inasmuch as the experiment Of discharg-
ing 6 1000 charges by means of one battery
has never been tried and by this system
it is claimed that, although one battery
should fail TO ignite all the charges stimuli
taneously, yet the discharge will, never
theless be instantaneous, 1t is expected
that the blast-which it has been proposed
to have on the 18th Of July, 1876, in ccle-
bratlon of Americas centennial-will en-
tirelY demolish the undermined two and
a half acres of rock and break it into small
pieces, which can be removed by dredg-
ing This will necessitate an additional
outlay, as estimated by General Newton,
in his recent annual report to the War
of about $3.50, 600 for the
next fiscal year AS regards the explosion
OF SO large quantity of nitro-g lyccrine,
Captain Heuer does not anticipate that
there will be any great shock to the neigh
nor that there will be the least
danger attending the blast as upon pre-
Nlous occasion, when he fired IL blast of
AZ 900 pounds of powder in the San Fran
cisco Harbor.
The only external visible effect was the
elevation OF an immense volume OF water,
whose transverse diameters were POO and
25O feet, to q height OF about one hundred
and fifty feet. Here, as will be the case
in the expected explosion at He'll Gate.
the water was let into the tunnel, thus OBJ
Grating as 4 tamp.
EXcavating is still going on at Flood
Rock, although the work will be necessar-
lily delayed until after the great blast ut
liallet's Point is over. There are ut pres
ent only about ten men engaged upon the
work. A shaft sixty feet deep has already
been sunk, and two tunnels, each about
twenty feet long, have been excavated,
the one running across towards the New
\ DIRK shore and the other in the direction
Of lIallett's Point. IL is thought that il
will take about two years to complete the
work, by which time nearly all of the OBJ
structions will have beer removed from
the neighborhood of Hen Gate. IN. Y. |
Herald.