The Toledo chronicle. [volume] (Toledo, Tama County, Iowa) 1873-1924, 1876-03-16
A Giant Fire-Cracker.

Ten years ago the War department dl-
rected Gen. John Newton, Of the United
States Engineer Corps, to make estimates
for the removal of the distractions in the
East River at Hallctt's Point, Familiarity
known as Hell Gate" Many attempts
to remove the distractions had been pre-
viOusly made, but had altogether failed
in the one great end-that of rendering
the channel safe and deep enough to adj
nit the passage of large vessels. Upon
the receipt Of the Generals report the
sum of $34, 900 was raised, partly by sub
scription among our local merchants and
partly by a grant from Congress. The
survey for the work was made in 1869.
The work itself involved the removal of
the Middle Reef, Gridiron, Hen and
Chickens, and Negroes Head; virtually
the complete demolition of Hallett's
Point. In September, 1869, the first ma
chinery was erected and the work of bur-
rowing into the heart of the submerged
rocks progressed slowly but surely. The
unwise delay Of Congress in appropriating
the necessary funds, and the niggardly,
paltry allowances made hampered the adj
yanccment Of the scheme. At last, how
by the bulletin, that the chamber prepared
for the great charge which is to rend the
stony mass TO splinters and make Hell
Gate a terror of the past is as large rs it
is required to be. By this explosion the
eastern entrance to the port of New York
will be opened to vessels of twenty-six
feet draught. The cost Of the affair in
money has been, so far, $4,000.
The work has been under the direction
of Gen. Newton, and deserves special
record in the annals of American engi-
neering. At the extremity Of Hallett's
Point, which is laid bare at low water,
central shaft was sunk, and the ledge of
rocks into which it descended was sur
rounded by a cotTer-dam to guard the
workings from high tides. From the
main shaft ten large headings radiated,
like the spokcs Of a wheel, running out
into the river-bed and under the reefs
which it was necessary TO remove. From
these twenty-eight smaller drifts were
driven. The larger shafts, the chief of
which was 200 feet long, were named
after various United States officers, as the
Grant, Mcclellan, Meade, etc, galleries,
aad were connected at regular distances
by lateral galleries, circular in form and
,t,i,, tn of oh
Twenty-Five and One-half acres were
undermined in this way, and one and
half miles Of tunneling made. The great
danger attendant on the work was, of
course, that likely to result from the cav
ing of the roof rock. To fully guard
against this soundings were made all over
the work at regular intervals of one foot
In ordinary cases the lead was sunk, but
sounding instrument was driven through
the bed rock by boring. But few short
of 30, 600 of these measurements were re-
quircd to establish the necessary knowl-
edge of the ground. The best comment
on the correctness of the measurements
arrived ct is in the fact that no serious
case of caving in the galleries has &C.
Cured since the work was commenced.
An enormous quantity of blasting ma
terial was used; at first nitro glycerine,
but later an agent composed of thirty
parts of nitro lycerine to seventy OF gun
powder. This compound, called vulcan
powder, answered the requirements better
than any other, producing the short,
quick blast required to marvel. Explo-
sives, equivalent on the whole to 150, 900
pounds of nitro ycerine, have been con-
sumed in bringing the work to its present
state.
To-day the mine is to receive the final
charge; in the pit or chamber, which is
thirty five feet deep and 200 feet in dame
ter, 10000 small holes, two and a half
inches in diameter, and from seven to
twelve feet deep, are being drilled in the
roof and sides of the passages for further
blasts, and are to be charged with the eX-
plosive incloscd in iron tubes. In the
matter of that explosive the engineers are |
NJ present in doubt From among the en-
ire list of blasting material at their COM
mand they desire TO select that which can
be most certainly relied on for effective |
work. The choice has so far narrowed |
Town to two, respectively known as Rend-
rock and Kieselguhr. The latter is a
German compound, an especial favorite
n the extensive workings of the Prussian
mines. The charges are to be simulta-
leously ignited by percussion, with caps |
similar in principle to those of a gun.
Forty thousand pounds of nitro glycer-
ne are to form the grand charge. The
discharge of the various blasts is to be eff
ected by electricity, and, in order to
void the possibility of an irregular series
If explosions, Gen. Newton proposes to
connect tie mines by means of an electric
wire inclosed in iron tubing and carried
bout the entire workings, cemmunicat-