, 1886-01-08

cumbersome wagons, laden with i'm
mense bulks OF steel, being slowly drawn
toward the yard, six horses to each
wagon. These were the tubes and jack
ets,- out OF which are being produced
guns that are as beautiful as they are de-
structive. The tube is the foundation OF
the gun. extending its entire length,
over which strengthening rings are
placed, the principal OF these being the
jacket" which is one-third the length OF
the and bands the entire breech.
Some OF the single pieces weighed us
much as 1900 or 10000 pounds.
SLOW C OF ROUGH BoRISG.
on being brought to the maynard they
were rough bored. This is a slow process,
which many visitors watch, scarcely
knowing what is being done, as an i'm
mense tube like hat OF n ten inch gun,
for Instance, nearly two feet In diameter
and t~wenty-seven and one-half feet in
length, weighing about 10000 pounds, is
seen on a lathe, slowly revolving, while
the chips Of the metal fall to the ground,
all the while being constantly watched
by the machlnist. The ladies always
pick up the metal shavings as they drop,
but let them fall rather more eagerly.
They find them rather scorching hot, and
content themselves TO wait till a chip
cools before placing is in their sachels
along with other relics. At last, when
the boring head appears at the opposite
end OF the tube from which II entered,
having made its slow journey through
the solid metal, the tube Is returned TO
the works to be oil tempered, by which
the steel Is raised to the requirements.
When the large tubes a been re-
turned to the yard tempered, n the
small pieces nave been treated likewise,
they are again ready for the machinists'
skillful hands. The tube is again placed
on the lathe. and the work OF smooth
boring begins, and when n hears re-
marks about having 1t made n thou
sandth of an inch larger, or OF other
measurements in that neighborhood, a
realization of the accurac necessary
dawns upon them. After the smooth
boring process the rough, ungainly piece
Of metal begins 10 enter into n new ex-
istence.
MYSTERY OF THE CLOSE JOINTS.
The best comparison that can give one
an idea Of one of the completed guns he
has never seen, Is to say that they look
like large, bright telescopes with parts
extended, only the sighting is dom ut the
opposite end. We ind the table spoken
Of about three-fourths covered with its
Jacket and rings, which encircle the
tube, making 1t largest at the breech and
smallest at the muzzle. These are so
closely fitted on that one would at first
think the whole gun wRs-one solid piece
OF metal The uninitiated can ave the
mystery Of the close joints explained by
leaving the finished guns and going over
TO the ordnance foundry again and see
t. A. -. - .AaANsAtNar - 90 ~
shrinking the jacket and rings ON tbs
tube.
The first piece to go on the tube is the
Jacket which covers the breech OF the
tube to the extent of one-third OF the en-
tire length, which tube is at first as sim
Pile in its form as a blow-pipe. This will
be found standing on the ground on end.
1t will be something like five to eight
feet high by four in outside diameter.
Beside this jacket from six to eight rings
90 on this gun. II the tube Is about to
be "jacketed,n as 1t is called, that Is
placed in position on the tube, a wood
ire will be found to be burning both on
the inside and the outside OF the jacket,
and n machinist will be on hand, and
every short time will Measure the inner
diameter to see when IL has been ex-
banded by the neat sufficiently to go over
the table, and this is the way in which
the mystery Of the close joints is cleared.
The Jackets inner diameter is made
about two one-thousandths OF an inch
smaller than the tube over which II is to
pass, and can only be passed on by this
method OF expanding the metal.
HOW A JACKET" is U ON.
While the preparatory work is going
on the foreman will likely explain some
thing about the philosophy OF putting
these rings on the u b TO form the gun.
OF course they are to give strength, and
we at once understand that, II the tube
should crack, the rings being separate
pieces, and covering nearly the entire
length, would prevent an explosion.
The reason for several rings, instead Of
one large one, is partly, at least, the
samoa rupture OF the entire gun max
ing it necessary to rupture nearly all the
rings.
When It is announced that the jacket"
has expanded sufficiently, a derrick is
swung around, and soon the place Is
raised and carried around 10 where the
tube is stationed, firmly fixed in an up
right position, standing in a pit, so as to
bring It's top about level with the ground.
Over this the Jacket" is lowered, 80
simply that the fact OF the close measure
ments are forgotten by the idle lockers
on. The Jacket" gradually cools, and.
contracting. clasps The tube as one piece.
The reason for the absolute pre-
olsion necessary in fitting the jacket
on the tube il apparent To great
a shrinkage. which would be the ease II
the Jacket was too small, would strain
the mettle, and too little would pre-
vent the metal from having a tight hold.
The contraction Of the metal forms u
cold weld" and gives a constant press
ure by the Jacket" upon the inner walls
Of the tube. II often happens that his
pressure contracts the bore OF the tube
sufficiently To require the boring-head TO
be run through again in order TO make IL
uniform. After this the rings are shrunk
on In the same way, over the Jacket,
and over the tube from where the
Jacket" ends toward the muzzle. The
rings are about three feet long, and add
about a foot and a hall To the entire
diameter OF the gun.
II will sometimes, though seldom, hap
pen that a jacket has 10 be emoved from
It's tube, which gives another interesting
sight. To do this the gun Is raised in an
upright position, with the Jacket end
down, 30 hat moaltsp metal may be
poured in around the jacket, giving It an
expansion sufioient to draw II out. The
main point in this process Is to raise the
tubs from its jacket a. soon a. II is loos-
ened, as. during a abort delay, the tube
would expand propertonately, which, OF
course, would prevent Its Withdrawal
Washington Cor. Minneapolis Tribuns