The Eddy current., 1898-10-08

Assembling the Huge Forginss AZ the
Washington oun Foundry.

Assembling the Huge Foreiurs a. ths
Washington oun Foundry.
The guns are made OF what Is called
forged steel. This steel II made by
private firms principally az the famous
Bethlehem works IN Pennsylvania, and
Is sent 10 the gun-foundry In the shapea
~ large tuhea. and In other shapes
called jackets and hoops. These steel
pieces. after being finished. are put to-
gether and made into guns. The jack
et Of gun IL about half the length of
the tube. aud Itself Ia really n large
tube. The inner tube, when II arrives.
IL put into a lathe. and has the hole
bored out 10 nearly the size II will be
when finished; then u IL turned down
Inside for about half its length from
the rear or breech end 20 its proper
size Turned down" means that the
metal Ia cut on with n steel cutter. The
Jacket also Ia bored out smoothly and
the hole carefully measured. The dia-
meter OF this hole. or bore. IN the Jack
81 ~ n little emaller (some hundredths
Of an inchl than the outside OF the
tube after being turned down. over
head IN the shop are big cranes which
travel back and forth on tracks. and
which can easily llft and carry heavy
weights. The largest crane Is called
the ii0-lon crane but Il viii ~, a
weight even greater. Near the center
OF the gun-shop ls a large pit In which
there are furnaces After the tube has
been bored out and turned down out
side. II II carried by n crane and lower
cd into the plt near the furnaces, 90
that Il stands on rs muzzle end. the
breeoh end being M IN the air. The
Jacket is also lifted and lowered into
furnace and heated This furnace
has a top. or cover. which lifts on. and
which is put on after the jacket has
been lowered into Il. Hot air IL forced
into this furnace. which heats the jack
ct tiR II expands 10 that the size OF It's
bore becomes greater In diameter than
the size OF tho tube Il rs 10 inclose
When all II ready. the cover Is lifted
from tho furnace. the crane hooks on
10 the jacket. lifts II out OF the fur
mace. and swings II over the tube. The
jacket Is then quickly measured. and
carefully lowered over the tube. which
Is standing on its end a stream OF
cold water Ia then admitted into the
lower end OF the tube. This water rls-
a. nearly 20 tho ton Of the tube. and
helps 20 cool both tube and jacket, now
fitted together. A. the jacket cools II
shrinks to It's proper size. and 80
squeezes and holds the tube tight With
In. When both are cold. the partly
made gun is lifted out OF the pawn
into another lathe, and turned Nsp,K
outside 30 as 20 be ready 10 have tho
hoops put on. These hoops. which have
been bored out tc the proper size. are
heated and shrunk on over the gun
Just aa the Jacket was shrunk on over
tho tube. Tho whole gun IA made. or
built up in this manner. After all the
hoops are on. the gun is bored out
again 10 final size. put into a rliiing
m chine. and rlned; that Is, Il has
grooves cut inside OF the bore through
out ita length. These grooves com
mence nt the muzzle. and gradually
curve tlll they reach the end OF the
bore. They are cut by what Ia called
a rifling-bar. which ia a long shaft
with cutters az ono end The gun re-
mains steady. while the bar enters in
TO the gun at the muzzle. and turns at
the same time, thus cutting what are
called spiral grooves throughout tho
length OF the bore Of the gun. This
riding Is done 80 as TO give the shot or
shell. when the gun ~ fred. a twirling
or rotary motion, which prevents ~
from tumbling end over end and caus-
90 II TO keep pointed IN the right dlrec-
tion. Tho shot or shell (proioctilel Is
long. and has copper band fitted on
IFS rear end. when the gun Is fred.
this copper band, being softer than the
steel OF the gun. enters into the grooves
is turned by them. and gives the pro-
jectile a spinning motion during its
flight.