The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1898-07-29
SHOCKS FROM FIRING A BIG GUN.
Physical Effect Upon the Men Standing
Near,
(From the Philadelphia Times.


OF just what happens when big cannon
is fired. The physical manifestations are
numerous. Even professors of chemistry
ana phylcs are stumped when they want
to dlrerentiate all the gases set loose and
the peculiar effects they induce. The
putfs OF whitish smoke, the flash of fire,
the roar and the recoil are all familiar;
but back OF these is a complex mass of
phenomena most bewildering to the mind
of any but an artillery expert.
First, the cubes, disks, hexagons, or ir-
regular Jumps of powder are chemically
transformed into powerful, expanding
gas the instant firing takes place. Then
there are innumerable by products that
even chemists do not understand.
The explosion of gunpowder is divided
into three distinct stages, called the
ignition, Inflammation and combustion.
The ignition is the setting on fire of the
first grain, while the Inflammation is the
spreading of the flame over the surface of
the powder from the point of ignition.
Combustion is the burning up of each
grain. The value of gunpowder is due to
the fact that when subjected to sufficient
heat it becomes gas which expands with
frightful rapidity. The fo-called explo.
sion that takes place when match is
touched to gunpowder is merely a chemi-
cal change, during which there isa sud-
den evolution of gases from the original
solid.
1t has been calculated that ordinary
gunpowder on exploding expands about
5000 times, or fills space this much
larger than when in the solid form. When
this chemical change takes place in
closed vessel the expansion may be made
to do work like that of forcing a pro-
jectile along thu bore of the great gun to
test the tube In the line of resistance.
The hardest work a gunner is called
upon to do is to stand the tremendous
shock. The forces exerted by these gases
in expanding seem to radiate in all direc-
lions from the cannon, as ripples are
caused by dropping pebble in pool of
still water. AS matter of fact it has
been discovered that these lines of forces
are exceedingly complicated affairs, and
play very queer pranks about the cannon
AS result few peopl know ust which is
the safest or the most dangerous position
for gunner to take beside his gun. In
the case of the great 13-inch guns on our
pOSlUlOA DtGh vi UAo III 10
much easier than one nearer the nisfzZle.
In addition to this force, there is an i'm
mense pressure exerted on the side of the
cannon so that another distinct series of
shocks also radiate outward from the
barrel of the gun. These lines of force
are Influenced, besides, by the recoil of
the gun, which tends to make the lines
curve outward and intensifies the shock.
These are in turn more or less conpen-
stated by the forces of air opposing them
as it rushes into the mouth of the cannon
when the projectile leaves it. AS result
of all these forces the atmosphere is of
course, violently disturbed. Although no
projectile strikes the gunner who must
stand by, it will be seen that the air is
full of missiles in the form of invisible
lines of force OF vibrations, which bonn
bard, as it were, every part OF the gun
nsr's body at the same time.
An examination and analysis of the
effect produced upon the human system
and the mind by the firing of a cannon is
most engrossing. Men generally counted
courageous tremble violently in their
knees; others feel nauseated; some have
severe headaches; few have had their
ear-drums split or the act ion of their
heart affected.
Take the vital organ-the heart--frst.
In the space between the right auricle
and ventricle are set of fine. threadlike
ion makes them tremble like timbers in
building when there is an earthquake In
n weak man the chamber of the heart Is
left open for an infant, the opening and
closing springs lose their control the
heart shakes; possibly the coTdae tendin-
lac are snapped; contraction or dilation
of the organ ensues and in some instances
death follows.
Deafness induced by an explosion may
be traced to the sudden pressure upon the
iuner orif1ce of the ear and the tremen-
dous vibration set up. The thin trans.
parent, fairly bright membrane called the
drum of the ear is burst, like piece of
tissue paper. held taut, and foroibly blown
upon. Sounds are conveyed by the beat
ing of tiny mallet upon this anvil. If
the beating is too rapid and too forcible,
the mem branes may be ruptured, atem-
porary disturbance of the mind occurs
and the sufferer becomes dizzy. When
the knees tremble it is due to the nervous
shock produced in the cherebellum. All
the nerves and muscles are thrown into
ateuic contractions and relaxation and
the knees appear to give way.
Nausea is also caused by the physiologi-
cal change that takes place in the brain.
There is a pressure of blood there, and the.
stomach, responding, tries to empty