The Van Buren press., 1894-06-02

ready for manufacture when 1T reaches
the gun foundry.
Of all of the processes which gre gone
through with at the navy yard gun
foundry In the manufacture of large
cannon. the preparation and placing OF
4 Jacket Is the most interesting The
Jacket Is q large cylinder placed over
the original tube at the rear, and cons
passing the powder chamber to give it
greater resistant strength. The
Jacket forging is bored up from the in-
side to diameter slightly less than
the exterior diameter of the tube
which 1t is to encircle. The jacket is
then expanded by heat in hot air fur.
mace, and, lifted carefully by means OF
a crane, is placed directly above the
original tube which is perpendicular
and securely held with the breech up-
ward. The Jacket is not only heated
to o white heat, but to an almost I'm.
perceptible dull red. 1t Is allowed to
descend from the crane accurately and
to slip down over the breech end OF
the tube, the expansion of the heated
metal OF the jacket making this move.
ment possible, notwithstanding the
fact that the inner diameter of the jack.
ct is somewhat less than the outside
diameter of the tube when the jacket is
cool. This process of putting on the
Jacket is one of the most remarkable
pieces of skilled work that can be done
with machinery. When the jacket is
finally lowered into its place over the
rear Of the original tube, the jacket
fits tightly over the tube and COM
presses it as it becomes cool. By this
operation the tube and jacket are prac-
tically combined into one piece.
There are four hoops also bored out
to diameter slightly less than the re-
spective portions Of the gun which
they are intended to encircle, and one
after another they are put in place by
the same process as that used in jack.
citing, the metal cooling and contract
ing, and compressing the inner layers
firmly in its embrace. The great cam
non is thus thoroughly reinforced and
then the work of rifling and finishing
begins Tho first thing to be done
when all the Jackets and hoops are on
is to take the gun from its upright
position, put it on lathe and have it
turned down over its whole inside to
the finished dimensions necessary to
its completion. When you remember
that each one Of these guns weighs
sixty-fve tons, You will realize that
the mechanism in the gun foundry
which picks up and lays down and
moves around these immense bodies OF
steel must be an approximation Of per-
lection. This work is only rendered
possible by reason of the fact that the
gun foundry contains eight prodigious
gun lathes Of unique design and UNI
limited power; and that the lifting
power OF the crane is limited only by
the horsepower of the steam engines.
One of the immense lathes In the gun
foundry has capacity for boring guns
fifty-one feet in length and Of turning
tubes OF ffty-seven feet, and conse.
quently could bore guns OF sixteen.
inch caliber.
The process Of rifing gun is very
interesting indeed. The interior sur
face Of the bore is cut with fifty-two
spiral grooves, each of which Is five-
hundredths of an inch deep and about
half an inch broad. Into these little
grooves will fit the projectile to be
be used, which Is encircled at it's base
with soft copper band slightly larger
than the caliber OF the gun. The ac-
ton OF the powder charge forces the
proiectile through the bore and the
rifle grooves into this copper band
give rotation to the projectile. The
rotation insures greater accuracy in
firing and has the still more important
effect Of keeping the projectile point
headed foremost from the time ii
leaves the muzzle until the time it
strikes the object at which it is aimed.
1t is interesting to see one of the
great cranes travelling from one end OF
the big shop to the other, noiselessly,
smoothly, stretching from one side OF
the ceiling to the other, Its little
wheels we'll oiled and not sound TO
be heard save when the clanking
chains are let down to encircle some
heavy object. Tho man who stands in
the crane, and is its engineer and di.
rector, is SO high In the air that he
looks like mere boy. While it may
be true that the hundreds of men be-
low who are rifing, polishing, finish.
ing and perfecting the great gun may
be more scientific, and their work may
be more important, nevertheless, when
you visit the big foundry, you will
carry away with you a more distinct
memory of the man in the crane than
Of all the other wonders of the place.
SMITH d. Fry.