Knoxville journal. [volume] (Knoxville, Iowa) 1874-1986, 1875-11-11
The Great Blast.

The work OF dee peEing and enlarging
the East River channel NJ Halietf's Point
is fast approaching completion, and 1t is
now attracting the special attention of
engineers and men Of science throughout
the country. Owing 10 the peculiar for
nation of the rock at Hallett's Point, To-
getber with the narrowness Of the present
channel. and the almost uninterrupted
passage OF vessels, the work has been done
under many Instantaneous circum-
stances After tedious work OF nearly
six wears the task Of excavating has at
last been completed. and the secondary
work Of preparing for the grand blast IL
now going on. lnasmnch as the ex-
plosive power To be used on the final blast
will be about 5000 pounds of nitro
plyeerine. or about eight times as much as
has ever been simultaneously discharged
before, much interest and not little
anxiety Il being manifested In the result.
The work, which Ii being superintended
by Mr.. William III. Heuer, was begun In
1869, and the amount expended on 1t has
been roughly estimated al about $3.50, 900.
Tie excavation extends under two and
half acres Of gneiss rock, vertically
stratified and running in northeasterly
and southwestcriy direction. Starting
from main shaft ihirty-four feet below
mean low water. ten main headings Stop
ing down to fifty-two feet below mean low
water have been extended out To an
average length Of $50 feet each. The
height Of these main headings varies from
eight 10 TWENTY-FIVE feet each, with an
average widtli Of fourteen feet From the
main headings intermediate headings have
been cut, and at uniform distances circular
galleries have also been cut across the
headings, thus forming series Of piers at
their points Of intersection. There are In
all 173 piers. which form the entire sup
port Of the roof and Of the water above 1t,
and which also separate the fory-one
headings and ten galleries. 1t Is estimated
that the entire amount Of rock 10 be broken
by the proposed blast will aggregate about
Al 900 cubic yards. Since the completion
Of the excavation and the bringing down
Of the piers 10 AN 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 txenty-four hours.
The working fe.cc fGw engaged in this
work il 100 men, divided into three gangs,
each OF which work eight consecutive
hours, in order that there may be no cessa-
ton.
Capt. Heuer expects 10 complete the
drilling about the last Of January, when
the important work Of charging each hole
will be- begun. This will have 10 be done
by experienced workmen with great care
and will probably 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
means Of series Of small tubes filled with
the nitro. glycerine. This precautionary
measure will he taken inasmuch a. the
experiment Of discharging 5000 charges
by means OF one battery has never been
tried, and by this system II Is claimed that
although the battery should fail 10 ignite
all the charges simultaneously yet the
discharge will nevertheless be instantane-
Gus. Ii is expected that the blast, which
il has been proposed TO have on the
Fourth Of July, 1876, in celebration Of
Americas Centennial, will entirely demol-
ish the undermined two and half acres
OF rock and break II into small pieces,
which can afterward be removed by
dredging. This will nccessitatc an add.
tonai outlay, as estimated by Gen. New.
ton In his recent annual report Of the War
Department, OF about $3.50, 900 for the next
fiscal year. As regards the explosion OF
so large quantity Of nitro. glycerine Capt.
| Heuer docs not anticipate that there will
! be any great shock W the ne.ghborhovd
nor that there will be the least danger at.
tending the blast, rs upon apreyious occa-
sion, when ho fired blast of42 900 pounds
Of powder In the San Francisco harbor,
| the only external visible effect was the
| elevation of an immense volume OF water,
whose transverse diameters were 200 and
| $50 feet, 10. a height Of about $50 feet.
Here, as will be the case in the expected
| explosion at He'll Gate, the water was let
| into the tunnel, thus operating AZ lamp.
| Excavating is still going on at Flood
Rock, although the work will be necessa-
rily delayed until after the great blast at
Ifalletts Point IL over. There are at 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 excayated,
the one running across toward the New
| York shore and the other In the direction
of Hallett's Point. II il thought that 1t
will take about two years 10 complete the
work, by which time nearly oil Of the OBJ.
structions will have been removed from
the neighborhood Of He'll Gate.--H N. 4.
| World.