The Hartford republican. (Hartford, Ky.) 18??-1926, 1914-05-29
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 a Hundred
Rounds, and That In Actual Time Of
Shell Passage Means Three Seconds.

S"e" TassaSe "ed"s tVree Seconos.
In the manufacture Of big guns tn,
engineer has certainly achieved some
of his most daring conquests. for 1t 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 ton mt speed
of thirty-five miles a minute. or 2,lOO
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 flight.
| 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 a twelve
inch gun huge solid steel ingot Is
cast. weighing upward of thirty tons.
The ends having been cut off. the in.
got is mounted in lathe. and tube
like ''trepanning" borer removes a 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 $500
ton forging press. which gradually
thins and draws it out along the bar.
which is kept cool by water circulat.
ing through 1t. After being turned
outside and bored inside the tube has
to be tempered. and this Is done by
dipping 1t into tank filled 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 I'm 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
state of dangerous tension. To avoid
such thing happening one part is
cooled artificially by means of water
jets. while the other portionsare 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. us metal arranged In this
manner withstands bursting strains
better than anything yet devised. A
twelve inch gun consumes no fewer
than 100 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 II
must be given twisting motion round
ts axis-in other words. be made to
spin. This rotation prevents its turn
ng head over heels, as it undoubt-
IDLY would do If not spinning. and |
makes 1t travel farther and more ac-
The spinning motion is |
about by rifiing-the cutting |
Of spiral grooves in the bore. or in
ide Of the gun. This is done by
Ong, hollow steel rod. which carries
hree tools ut the end and cuts three
,rOOves at once.
As the rifiing comes so near the
md of the manufacture of big gun
t must be conducted with the great
st care. for single badly cut groove
would spoil the gun. now representing
'erhaps $4,000 In work and material.
indeed. extreme care and accuracy
every process in the max
ng Of heavy ordnance. The steel for
he tubes is made carefully: the ingots
re cast carefully and forged careful
=. Every tube is bored and turned
D the fve-hundredth part OF an inch.
'hOugh a twelve inch gun is nearly
wenty inches thick over the powder
each of its various jackets
lust have its proper tension in order
, receive its fair share OF the shock
explosion.
Finally, there is the breechblOck- ,
lie door through which the shell Is in |
srted. 1t moves on Il hinge and Is a
cry massive affair. weighing about
llf ton. Thanks to the presence of !
srtain levers and the perfection of q
lie workmanship. any one who has [
lie knack can move II quite easily. 1t I
IN be slammed and locked in about
We seconds. The door gives entrance
the twelve foot chamber where the
lell Is placed.
The active life OF gun is made up '
the total Of the very short periods |
'cupied by the various shells passing
trough its bore. The bore of
gelye Inch gun is about forty-fve feet "a
NJ. and the average rate at which
e shell travels through II IL halfway
tween M motion at all and the muz-
2 velocity of. say, g, ono feet Der sec 5