The Richmond climax. (Richmond, Ky.) 1897-1914, 1914-07-01
MAKING A BIC Gun
One of the Amazing Conquests OF
Modern Engineering.
WEAPONS WITH SHORT LIVES.
The Monster Twelve Inch Rifles Are
Useless After Firing Hundred
Rounds, and That In Actual Time of
Shell Passage Means Three Seconds.

Shell Passage Means Three Seconds.
In the manufacture of big guns the
engineer has certainly achieved some
of his most daring conquests, for it is
doubtful if there is anything more
wonderfully fashioned or scientifically
constructed than the monster weapons
found on the latest battleships and in
large forts.
From their muzzles they are capable
of launching into space shells weigh
ing as much as half a ton at a speed
of thirty-f1ve miles a minute, or 2,10O
miles an hour. These death dealing
missiles may be so designed as to
burst after they have forced their way
through a ships side or Immediately
they strike an object or at some point
during their fight.
The big gun itself consists of sew
eral tubes, or cylinders, slipped over
one another and named after the let
tiers of the alphabet. "a" is inside
and scorched by the powder gases.
"B" goes over "A" and so on, the out
side tube Of all being known as the
jacket.
Each separate tube, or cylinder, is
fashioned in much the same way. In
the case of the "a" tube for twelve
inch gun a huge solid steel ingot is
cast, weighing upward of thirty tons.
Il off hn i'm
got is mounted in lathe, and tube
like ''trepanning" bOrer removes long
core from the center. The ingot is
then dismounted from the lathe and
heated. A long. hollow bar somewhat
smaller than the destined bore of the
gun is passed through the central hole,
and the ingot is placed under a $500
ton forging press, which gradually
thins and draws it out along the bar,
which is kept cool by water circulat-
outside and bored inside the tube has
to be tempered. and this is done by
dipping it into tank filed with thou
sands of gallons of cottonseed OIL.
AS it would be impossible to slip the
''B" and &c" tubes over the "a" tube
when cold. this difficulty is got over by
heating them. The work, however, re-
quires great care and constant atten-
ton. The heated cylinder, Of course,
decreases in length as well as in diam
eter as it cools. and, unless great pre-
cautions are taken, it would naturally
cool at the ends first, and cause the
central part of the tube to cool In a
state of dangerous tension. To avoid
such a thing happening one part is
cooled artifcially by means of water
Jets, while the other portions are heat
ed by gas flames.
We now come to the wiring process.
Layers of ribbon-like steel wire are
wound outside the innermOst cylinder
but one, as metal arranged in this
manner withstands bursting strains
better than anything yet devised. A
twelve inch gun consumes no fewer
than 40 miles of wire, one-quarter
inch wide and one-sixteenth of an inch
thick.
That the shell may travel business
end" foremost throughout its journey it
must be given a twisting motion round
its axis-in other words, be made to
spin. This rotation prevents its turn
ing head over heels, as it undoubt
edly would do If not spinning. and
makes it travel farther and more ac-
curately. The spinning motion is
brought about by rifiing-the cutting
Of spiral grooves In the bore, or in
side Of the gun. This is done by a
long, hollow steel rod, which carries
three tools at the end and cuts three
grooves at once.
As the rifiing comes so near the
end of the manufacture of a big gun
1T must be conducted with the great
est care. for a single badly cut groove
would spoil the gun. now representing
perhaps $4,000 in work and material.
Indeed. extreme care and accuracy
characterize every process in the max
ing of heavy ordnance. The steel for
the tubes is made carefully; the ingots
are cast carefully and forged careful
ly. Every tube is bored and turned
to the fve-hundredth part of an inch.
Though twelve inch gun is nearly
twenty inches thick over the powder
chamber. each of its various jackets
must have its proper tension in order
to receive its fair share of the shock
of explosion.
Finally, there is the breechblock-
the door through which the shell is in
serted. 1t moves on a hinge and is a
very massive affair, weighing about
half ton. Thanks to the presence of
certain levers and the perfection of
the workmanship. any one who has
the knack can move it quite easily. II
can be slammed and locked in about
five seconds. The door gives entrance
TO the twelve foot chamber where the
shell is placed.
The active life of gun Is made up
Of the total of the very short periods
occupied by the various shells passing
through its bore The bore of a
twelve inch gun is about forty five feet
long. and the average rate at which
the shell travels through it is halfway
between no motion at all and the muz-
zle velocity of. say. 5000 feet per Sec
ond. or about 1900 feet per second
The rifiing Of big gun is worn out
after 100 rounds have been fired. so
that the total life is the time taken
for a shell moving at 800 feet per
second to travel $500 feet--that Is.
just three seconds.