In fact, the amount of explosives consumed in the industries
is so great that the quantity employed for military purposes
sinks into insignificance. Yet we have failed to refer to those
industries--quarrying and mining, and the engineering operations--in
which they are most extensively and commonly used, being employed so
largely in mining alone that it is an almost daily occurrence for
blasts containing twenty, thirty, and even fifty thousand pounds of
explosives to be used in a single charge; and the system of large
blasts has even become common in hard-rock excavations, such as
quarries and railroad cuttings, while in the blast at the blowing up
of Flood Rock, in New York Harbor, October 10, 1885, over one hundred
and forty-one tons of rack-a-rock, dynamite, and mercury fulminate were
used in a single shot.
Nor have I alluded to the use of explosives by the anarchists in
their dastardly outrages, through which the safety of the old and
young, feeble and strong, the innocent and the offending, are alike
endangered; but I will touch briefly upon the applications of these
powerful agents in the too-much cultivated industry of safe-robbing,
since I was called upon some years ago to demonstrate, before a
Government commission, how safes might be successfully attacked either
in a burglarious way or by a mob with explosives, meaning by the
burglarious operation that the safe should be made accessible within
twenty-four hours with means such as a party of men could smuggle into
a bank and which might be used without attracting attention or doing
material damage to the building, and by “mob violence,” meaning that
the vaults are supposed to be in the hands of a mob which has ample
time and quantities of explosives at command, and does not care how
much noise is made or destruction is wrought, provided the treasure is
secured.
[Illustration: FIRING ON IRON DISK, RESTING ON LEAD DISK, IN TESTING
THE EFFICIENCY OF GUN COTTON.]
[Illustration: GUN COTTON DISK. With indented inscription, and iron
plate upon which the indented inscription has been reproduced.]
In the experiments made in a burglarious way, among others, a
three-thousand-dollar square safe of the most approved construction was
attacked by inserting in the crevice about the locked door four and
eight tenths ounces of nitroglycerin, and in eight minutes after the
operation of loading was begun the charge was fired, with the result
that the whole of the jamb below the door was blown out and a hole
made in the door of sufficient size to admit the hand and arm, while
the doors and divisions of the interior compartments were completely
shattered. On repeating the operation with four ounces and a quarter of
forcite dynamite the door was completely torn off.
Among experiments made to demonstrate the resistance of structures
to attack by a mob was one upon a safe twenty-nine inches cube, with
walls four inches and three quarters thick, made up of plates of iron
and steel, which were re-enforced on each edge so as to make it highly
resisting, yet when a hollow charge of dynamite nine pounds and a half
in weight and untamped was detonated on it a hole three inches in
diameter was blown clear through the wall, though a solid cartridge of
the same weight and of the same material produced no material effect.
The hollow cartridge was made by tying the sticks of dynamite around
a tin can, the open mouth of the latter being placed downward, and I
was led to construct such hollow cartridge for use where a penetrating
effect is desired by the following observations:
[Illustration: HOLES PRODUCED IN IRON PLATES BY BORED GUN COTTON.]
In molding the gun cotton at the torpedo station, as stated above, a
vertical hole was formed in each cylinder or block in which to insert
the detonator, and in the final press a steel die was laid upon the
cake so that an inscription in letters and figures was forced upon it.
This inscription was indented in the cylinders and was raised upon the
surfaces of the blocks. When the gun cotton was fired untamped, in
testing it, the cylinder or block was usually placed with the inscribed
face resting on a polished iron plate or iron disk, and after firing,
if the gun cotton had detonated it was invariably found that not only
was a vortex-like cavity produced below the detonator, but that the
inscription on the gun cotton was reproduced on the iron plate, and,
what was most singular, when the inscription was indented in the gun
cotton it was indented in the iron plate, and when the inscription was
raised on the surface of the gun cotton it was reproduced raised on
the surface of the iron plate. In experimentally investigating this
phenomenon I eventually soaked several cylinders in water, so that
I could bore them without danger, and then bored holes of various
diameters and depths in them, until in the last instance I bored a
vertical hole an inch and three quarters in diameter completely through
the cylinder. These wet cylinders were each placed on a similar iron
plate, a similar dry disk was placed on each as a primer, and they were
successively fired, when it was found that the deeper and wider the
hole in the gun cotton the deeper and wider were the holes produced
in the iron plate, until when the completely perforated gun cotton
cylinder, from which at least half of the weight of explosive had
been removed by the boring, was fired, the iron plate was found to be
completely perforated.
Advantage was taken of this action of the rapidly moving molecules to
produce some beautiful effects by interposing laces, coins, leaves from
the trees, and stencils with various devices cut in them between the
base of the gun cotton and the iron plate, for after the detonation of
the gun cotton the objects were found to be reproduced upon the iron
with the utmost fidelity and in their most delicate parts, and the
impressions were raised upon the iron as the objects had been before
the explosion.
In one instance a disk of gun cotton was placed in a tin which had
been used in canning peas. The disk was covered with water so as to be
completely immersed in it, and a second dry disk, with which to fire
it, was placed upon the wet one. The face of the can resting in contact
with the iron plate was originally the top of the can, through which
the vegetable had been introduced, and it was consequently grooved
where the cover was soldered on, and it also had an irregular drop of
solder over the vent hole, the solder being raised, therefore, above
the general level of the face. On firing, the can was completely
volatilized or comminuted as usual, but the face of the can was
reproduced in every feature and with the original values of the
surface, the groove being indented in the iron, and the solder being
raised above the rest of the impression.
[Illustration: MAPLE LEAF REPRODUCED ON IRON PLATE.]
In another instance a disk of gun cotton three inches in diameter was
placed in a tin can five inches in diameter, and the can, which had
a smooth bottom, placed on the face of an iron I-beam. The can was
filled with water so as to just cover the gun cotton, a second dry
gun cotton disk was placed on the wet disk of a primer, both being in
constant contact with one side of the can, and the system detonated.
As a result the can and water disappeared and the face of the beam
was torn off, but on recovering the pieces and matching them it was
found that not only was the smooth base of the gun cotton and the face
of the can reproduced in the iron, but in the space between the gun
cotton and the side of the can, occupied by the water, three distinct
sets of waves were produced, having an increasing amplitude from the
center proceeding outward. It is evident that many curious effects can
be produced with explosive substances, and I do not doubt that useful
applications will be found through a close study of the phenomena
attending them.