Elizabeth daily monitor. [volume] (Elizabeth, N.J.) 1868-1880, 1869-08-04
SIisabet9 9aiIp @l'9onitor, /.
PUBLISHED AT 155 BROAD STREET, BY
J.. MADISON DRAKE. "
MoDERN ORDNANCE.

|
ern Engineering, he said tsa'#
"Not long since witnessed the
penetration of wrought iron shield
| for an embrasure made of two plates
measuring together fifteen inches in
thickness by q cannon shot OF twelve
! inches diameter and 624 pounds weight,
fred from o constructive distance Of
500 yards. The active force of the
powder on the ball was 10000 pounds
per square inch, equal to 1920 tons,
giving it an initial velocity 1900 feet
per second, or 800 miles an hour"
The work" of cannon shot is in
direct proportion to its weight and the
square of its velocity, and the weight
of spherical shot are as the cubes of
their diameter. That is, a Rodman
gun of 90 inches diameter throws a
spherical shot of five times the weight
of one of II inches, but this large gun
has never been tried with elongated
shot, and the heaviest shot that has
been fired from it weighed 1,072
pounds
Krupps great steel gun, which was
exhibited at the Paris Exposition, has
been fired several times, throwing a
ball of 1000 pounds with velocity of
more than 1000 feet per second.
The "Swamp Angel used at the
seige of Charleston was Parrot rifle,
and threw shot of $50 pounds distance
of y miles with great precision.
One of the largest of the ancient can
non was the "Morris Meg" now to be
seen at Edinburg Castle. 1t has bore
of 90 inches, and threw stone balls of
1917 inches diameter and about 800
pounds weight 1t was used at the
siege of Dunbarton, in 1893, and was
injured by firing 200 years later. This
gun was once placed at Dover Castle,
and there was then upon it quaint in
scription in these words
"Load me well and sponge me clean,
And I'll drop you a shot at Calais
green.
The shortest distance across the Eng
lish channel is 16 miles, and General
Gilman says that this gun could not
possibly have thrown ball one-fourth
of the width of the channel.
The artillery officers of the present
day measure the force of cannon shot
with great accuracy by means of in
struments arranged for the purpose.
In the bottom of the cartridge is
placed cylinder of brass of two inches
diameter, into which solid piston is
close fitted, the bottom Of which is
armed with steel cutting tool and be-
hind it is placed disc of soft copper
When the powder in the gun explodes,
it reacts upon this piston and drives
the tool into the copper disc to depth
corresponding to its explosive force,
and by means of scale the gunner de-
termines the amount of this force with
considerable accuracy.
1t is of course to be understood that
the scale has been previously deter
mined by experiment by means OF
pressures applied to familiar discs.
The following is the method used to
determine the velocity of the cannon
shot: At short distance from the
muzzle of the gun and in the line of its
range small wire is stretched which
communicates with an electric machine,
and at exactly 100 feet another wire is
placed in the range of the ball also
communicating with the machine. The
ball in its flight cuts these two wires
and the electric machine records the
times of the breaking of each wire
but this space of time is so small (the
one hundred and twentieth part of a
second) that it would be impossible to
measure it with any approach to accu
racy.
The machine, however, is provided
with an apparatus which consists of a
smooth faced wheel of 10 inches diamo-
ter which is made to revolve with ex-
traordinary rapidity.
1t is known that the different sounds
in the gamut of the musical scale are
produced by vibrations, and the num-
Der of these vibrations for each note
has been accurately determined. These
range from 200 to 429 per second.
Placed over the face of the revolving
wheel is slender piece of steel whose
musical note determines how many Vi
brations it makes in second. This
tuning fork" lightly touches the face
of the wheel, and produces upon it
series of curved lines corresponding to
its own vibrations. A second of time
is thus accurately divided into say 500
parts, and indicated by 500 of these
curved lines. all of which are equi dis
tant. 1t will thus be seen that an ac-
curate measurement of time to 1900
the part Of second is obtained.
The electric machine is arranged to
make q cross mark over the face of the