National Republican., 1884-10-11

into ltS SeAU WIN several VuTus III Nuo piu-
nary manner. But as this would take up
too much time the threads of the block
arc slotted through or cut away to the
extent of one.half its surface, and CORE
spending slots being made in the threads
Of its scat, the block slides in without
turning, and when in partial turn
brings the uncut threads of the block in
position with those of the seat and the
breech is closed. This is technically
known as the Uninterrupted screw"
breech.closer. 1t is an invention of the
French, and bears the name OF an officer
Of French ordnance who perfected it
Col. DE Bange. II is now pretty gen.
orally adopted except in Germany and
Russia, where tho krupp or transverse
sliding block system is still in vogue.
The French or interrupted screw system
is superior in several important particu-
lars. 1t is simpler, stronger, and sator
than tho Krupp mechanism; it does not
require the awkward and cumbersome
breech extension, and IL is not so liaDle
to lock" or liam" in its scat by the
effect of conclusion OF heat IN firing. lt
is probably as near tho perfection CT a
breech- closing apparatus for heavy ord
nance as human ingenuity will ever
devise, in our time at least.
After tho completion of the breech
mechanism the gun is ready to be
mounted on ali experimental carriage for
firing tests. These tests are conducted by
a fixed standard of trial charges, which
are considerably heavier than those em-
ploycd In service. 1t will be remembered
that every piece of steel used in coustruc-
ton has been tested prior to being fitted
by cutting piece off one end aud asoer-
tanning its tensile strength, ductility, and
other qualities by actual stress in testing
machine; in other words, subjecting 1t to
actual tension up to the breaking point,
so that the strength of tho gun may be
calculated to nicely before it is fired at
all. The firing tests, however. are addi-
tionally necessary rs means OF determin-
ing whether the mechanical work of put
ting the different pieces together, has been
performed accurately according to calcula-
tiOn, and also to ascertain whether any
weaknesses exist in the metal by reason
of local flaws which may be in the
interior of the mass, and hence invisible
to the rigid inspection which follows
every step in the work.
The above description of the process of
manufacturing o modern steel cannon is
perhaps as clear as can be made without
rcsortinK to absolute hnicalities, which
probably would not materially aid the
comprehension Of the average reader.
The gun having thus passed all its in
spections and tests is now stamped on the
top of tho breech-coil with tho sheet
anchor of the United States navy and
numbered, when it is ready to be mounted
on board ship. The carriages on which
modern guns are mounted are machines
no less elaborate or ingenious than the
guns themselves. Practically there are two
types of gun carriages in naval use. Ono
is the muzzle pivoting carriage used in
unarmOred ships and broadside iron -clads,
and the other is the sliding trunnion-
block apparatus employed in revolving
turrets, where tho turret itself supplies
the pivot. 1t is probably not worth while
to go into detailed description of these
carriages, because it would necessarily be
more techical than q description of tho
gun, and it would not bo easy to find
popular terms by which to designate the
various parts or their functions.
Suffice to say that the carriage adopted
for the American navy is an improvement
upon tho English Scott carriage, and is
generally known among naval experts as
the Sicard carriage, most of the improve
ments having been conceived and de-
signed by Com modore Montgomery Sicard,
the present chief of the bureau of ord
nance, United States navy. 1t consists of
two principal parts: First, the slide, which
rests on the deck, and which is fastened
in front to fixed pivot. Tho slide con-
sists of two parallel T rails or beams, and
between them is seen q heavy cylinder,
or sometimes, if the gun is large, two
cylinders. These are hollow, and in them
travels piston-head whose piston-rod is
attached TO tho top carriage. They are
worked on the hydraulic plan. both for
taking up the recoil of the gun when
fired aud for moving it backward and
forward. ,,
The top carriage receives the trunnions
of the gun. 1t travels on the parallel
rails of the slide OH small anti-friction
rollers, and is fastened, as before men,
toned, to the piston-rod or rods of the
hydraulic compressor in the slide. The
top carriage contains also the machinery
for elevating and depressing the gun,
while the slide contains the mechanism
for moving it latorally around. its pivot.
These carriages, as well as the guns, are
being manufactured at the Washington
yard. The material of which they
are made is partly bronze and partly cast
steel, and they have the merit of being
the lightest gun carriages in proportion to
their strength aud mobility yet designed.
The number of guns now actually
under construction at tho Washington
yard, in various stages Of forwardness, is
fourteen. Of these two are 10-inch, four
are S-inoh, six are 6-inch, and two
are 5-inch. The two 10-inch guns are
part of the Miantonomoh's battery. and
are to be followed by the other pair as
soon as the steel for the tubes, jackets,
and hoops can be prepared.
The four S-inch, the six 6-inch, and
the two 5-inoh guns, are nominally for
the Chicago's battery, though they may
be mounted on the Boston or Atlanta,
and others made for tho Chicago. 1t
should be added that the 6-inch gun
and carriage designed for the Dolphin
have been finished and forwarded to New
York to be placed on her deck in posi-
tion.
A brief account of the dimensions of
those new weapons may not be uninter-
esting at this point. Let us begin with
the smallest and work up.
The 5inch gun is 12l feet long over
all. The rihed bore is 10 feet long, the
powder chamber, including tho slope of
the shoulder, is % inches in length, and
the breech block takes up the remainder.
The projectile of the 5-inch gun weighs
60 pounds, its powder charge 80 pounds,
and the gun itself 6,200 pounds. The
weight Of its carriage and slide we did
not ascertain, but it is probably not far
from $500 pounds.
The 6.inch gun Is 16 feet over all. Its
rihed bore is l2 feet In length, its powder
chamber 3 feet l inch. and its breech
block, with gas check, IL inches. Its pro-
jectile weighs 100 pounds Its powder
charge SO pounds, and the gun itself
1000 pounds. This 10 tho weight cal
culated mathematically by the officers of
the bureau; and it may be worth while to
state that the Dolphin's gun, which was
the first standard 6.inch rifle to be COM
pleted weighed on the scales exactly
ll,Ol0 pounds, or 10 pounds more than
the cslculation--an error of only nine
one'hundrodths of per cent, which, by
the way, is hardly sufficient margin to
allow for the slight modification of
specific gravity always incident to the
fOFpinU and nf v,alInakl.