The Florence daily tribune., 1899-01-05


tury-How the ProJectue Help. to
KIN the Gum.
The larger cannon the more extern
sive are the injuries it receives with
each successive discharge. All damage
done to a gun is internal. The separate
action of the powder and the projectile
damages the piece every time it is aimed
and fired Obviously the amount of the
damage depends upon the material aud
workmanship of the gun. Men who
make big guns describe the harm done
their pets with many intricate and puz-
zling terms of scientific turn. In one
case gun is damaged because the part
of the bore which contains the powGer
is enlarged. This happens when the
metal is compressed. and IL is more dan
gerous and more plainly seen If the
gunners have been using wads between
their explosive and their projectile
Then, again, cavities are produced by
the melting away of a part of the metal
by the heat of combustion of the charge.
Cracks come from the tearing asunder
OF the PARTICLES of the metal at the sur
face of the bore When il is first made,
crack of this particular kind is barely
peroeptible. but it increases each time
the gun is fired. Gradually it extends
completely through the side of the
piece. Tho crack usually begins at the
junction of the chamber with the bore,
simply because, as guns now are, this
part is not so well supported as the
others.
Edward S. Farrow, q. S. A., is au.
thority on damage TO guns, although,
like all others who have studied the
question, he does not agree with very
many authorities ON all the points to
consider in the life of cannon. He con.
tends that furrowing or scoring produced
by the erosive action of inflamed gases
is the great disease which attacks the
very big guns first. This particular in
jury is most apparent where the current
OF the gas is most rapid or at the inte-
rior orifioe of the vent and on the sur
face of the bore, directly over the seat
of the projectile. This scoring begins
very early in the life of very large
gun, but it is conceded that it does not
become very important until the piece
has been discharged considerably. Lieu
tenant Farrow describes this scoring as
resembling the bark of an aged elm tree,
the metal being eaten away into irregu-
lar burrows and ridges. In extreme
cases. however, scoring has not killed
the gun, although i'll some cases il has
acted ike wedge and split the bore at
the place attacked.
Where the action of the projeotile has
ruined the gun the damage has been
done around the projectile and in front
OF 1t. The elasticity of the metal and
the crowding up of portions of it in
front of the shot cause rebounding
process. The projectile, carried forward
by the force of the charge, strikes
against the upper part of the bore; then
il is sent against the bottom and again
bounds to the top, and so on until it
emerges from the piece The effect Of
this bounding motion is to raise and de-
press the gun in its trunpicn holes. The
accuracy of fire is Diminished, and, of
course, the gun is unfit for service.
nronze guns are the worst sufferers in
this way. Mortars-short and dumpy-
are not affected.
To stop the bounding of the projectile
gunners wrap the shell in cloth or pa
per or else shift the base of the mass
to be hurled. This last process is con-
sidered the best and is done by reduo-
ing the diameter of the cartridge and
adding TO its length. Projectile injury
is also caused by burrows or scratches
made by rough shells or case shot.
Small fragments, too, break away very
often from the shells and give the bore
grinding and cutting process, produo-
tive of great damage.
Enlargement of the muzzle is another
serious injury produced by the projec-
tile. This is caused by process which
seems unavoidable. AS the shell leaves
the piece it strikes against one portion
of the bore. The resistance at the mouth
being less than at any other point, the
metal naturally yields, and the muzzle
Of the cs~non is elongated in vertical
direction.
Some men who ought to know say
that 100 shots is the life of very big
gun-a l2 or 10 inch weapon. Others
place the number of shots at 400 or 500,
As matter of fact. it is all guesswork.
The great Krupp gun shown at the
Worlds fair and conceded to be perfect
or supposed to be so-has been dis
charged less than ten times, and it is
now believed to have reached its limit.
On the other hand, the big guns of the
American battleships have passed the
time allotted them by wise men who
know guns and apparently are as good
as when tested. How soon they may
yield, however, is not in the books.
Lieutenant Farrow says that very
large gun should not be expected to
stand more than 400 or 500 shots before
1t will be necessary TO open new vent,
closing the old one at its interior orifice.
When the gun dies-bursts-the lines
of fracture are photographed. Speci-
mems of the metal are SAVED. Tests are
made and conclusions drawn And Un-
i