The Portland daily press., 1876-09-22
He'll Gate.
From the N. Y. Times. ]


Since the days of the great Csrthaginian
General, the process of blasting and the mag
nitude of blasting operations have undergone
extraordinary development, and even the great
engineers of the Old World, whose business it
was to undermine fortresses, so recently as
within the time of the present generation,
would stare with profound establishment at the
network of headings and galleries with which
Gen. Newton has converted the reef at Hallet's
Point into an underground labyrinth of pas
eages The reef which is the scene of Gen,
Newton's operations lies Immediately off Hal
let's Points, in fact, submarine portion of
it. 1t is much in the shape of a sem-ellipse;
the base running almost in straight line from
east to west, and the apex pointing nearly due
north. The area of the reef is about three
acres; two and three-quarters of which have
been undermined. A fair conception of the
plan OF operations can best be given by COM
pairing the headings and cross-headings or gal
leries to the lines of longitude and latitude on
globe. The headings all radiate from the
shaft, which is in the centre of the base of
the ellipse, and the galleries extend in semi
circular form around the shaft On approach
ing the works, beyond large board marked
"Nitroglycerine, danger" there is nothing
whatever to intimate to stranger that opera
tions Of such gigantic magnitude are going on
in the immediate neighborhood-i~d deed at his
very feet-till he reaches the brink of the
shaft, into which all the headings of the mine
lead. But once at the mouth of the shaft and
an ominous change comes over the spirit of
ones Autumnal dream. Overhead a crane is
swinging in mid-air a box of dynamite car
tridges large enough to blow up a small city,
other boxes are lying around at the bottom of
the shaft, and in one of the tunnels others are
piled one on another, reminding one of the
boxed collins in the largs aud drsary receiving
vaults at Greenwood Cemetery. How the
soul of the monster Thomas or Thomassen
would have reveled 10 such scene.
The shaft is an irregular pentagon in shape,
III by 62 feet. aud having depth of 80 feet
below low water A light wooden staircase
leads down into the shaft, the bottom of which
would be perfectly dry but for the wet sawdust
with which it is covered. The sawdust is
precaution against conclusion in case a car
fridge should be accidentally dropped. From
this shaft, ten main tunnels radate, the tun-
nels varying in length fom 1856 to 800 feet-the
average length being 270 feet. The width of
the tunnels is about IA feet, and their height
the end The floor of the mine falls gradually,
the roof OF the excavation more rapldly-fol-
lowing the bed of the river above and keeping
up general average of ten feet of solid rock
below the water. Cross galleries, of about the
same height and width as the tunnels, traverse
the mine at iotervals of 80 feet. leaving the
roof supported by enormous columns of solid
rock. These columns, however, are cut through
by secon larry tunnels and galleries, increasing
the number of rock piers supporting the roof
to l73, of about 10 feet in thickness and giving
an aggregate length of tunnels and galleries Of
7,425 teet-4, 857 feet of tunnels and 1858 feet
of galleries. In order to cIeate this network
OF tunnels and galleries, it was necessary to
blast out and remove no less than 47,461 cubic
yards of rock. This work was begun seven
years ago, and was finished in June, 1875; and
since that time the pillars have been drilled 10
all directions preparatory to the insertion of
the cartridges for the grand and final blast.
The pillars and the outside walls of the mine
have been arranged in what are termed battery
groups; that is, for connection with the electric
battery which is to fire the blast There are
lS4 OF these groups, each group being drilled
for twenty charges, making $3.50 charges in
ALL But two. and generally three, cartridges
are charged into the same hole, according to
circumstances and the Judgment of the fore.
man who has charge Of the mining depart
ment; so, till the charging is actually finished,
no accurate figures. as to the exact amout of
explosive agents to be used can be given.
The work of charging the $3.50 drilled holes
has been one of extreme delcacy. Only the
most experienced ard tried men are employed,
and they handle cartridge as tenderly as
young mother handles her first bantling. The
cartridges arrive at the works packed horizon
tally in boxes of sawdust. Each one is careful
ly examined by the foreman as it is taken out
and if any particles of dynamite are found on
It they are dissolved by the application of alco-
hol and then washed off with water. And this
one particular alone indirectly compels the en-
ployment OF only those accustomed to handle
nitro-glycerine. The cartridges are about three
inches in diameter, and vary in length from
nine to twenty-four inches. As they are pass
cd after examination by the foreman, they are
placed in hand-barrows, arranged with a series
of cellular partitions, after the fashion of
the boxes in which soda water is carried
about, and are then carried by two men
to their destination in the mine Four thick
cartridge, and as the cartridge is carefully thrust
into its last resting place. these prongs being
pressed by the wall of the hole toward the line
OF the cartridge, resist the pressure and hold
ing removed from the hole the desired number
of cartridges are inserted, and everything is
ready for the worn of pruning. The printing
fuse is composed of wire and illuminate of mer-
cury-the compound universally employed in
the manufacture of percussion caps-inclosed
In thick copper cap, which is covered with
gutta-percha, the gutta-percha not only acting
as cushion but also preventing any injury by
water or da mp. The whole fuse is thickly coat
ed with paraffine, and is then inclosed in a tin
medically sealed. About two feet of each of
the wires of the fuse hang out of the printing
cartridge. SO as to enable the easy attachment
of the battery wire after the cartridge is placed
in position.
. The charging of all the 1874 groups is now
pretty well completed; the printing and attach
ing of the network of battery wires alone re.
naming to be carried out before all is ready for
the blast. About fifty feet south of the shaft
b-proof-similar to rifle-pits, but, of course,
far stronger, has been constructed of stout tim
bsr and earthwork. In this structure the bat
teries, with about one thousand cells, will be
placed. Wires will be run direct from the bat
teries to each group of charges; the first charge
co1nectiog with the second by wire, the second
with the third, and SO on till every charge in
the group is brought into indirect comruoica-
ton with the batteries. At the time of the
great blast these batteries will be discharged
from safe distance by means of closing Cir
cult, and the next instant the great explosion
will have taken place. 1t is believed the event
will occur on Sunday next, as near the middle
of the day as high tide will allow
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