The weekly pioneer and Democrat. [volume] (Saint Paul, Minn. Territory) 1855-1865, 1864-02-26
the GREAT GUN OF THE AGE.
Casting Of the 2O-inCh ROdman
Gun at Fort Pitt FOun-
dry, PittSburg.
The Casting a Complete Success.
FULL PARTICULARS OF THE
GREAT GUN JUBILEE.

The 2O-inch Rodman gun was cast at
the Fort Pitt Foundry, Pittsburg, on
Thursday noon. This immense gun which
was first suggested by Major Rodman in
his report on the trial of the first 15-nch
gun, has long been a matter of theory.
Preparations for its manufacture were
begun in May, 1863, and were continued
from time to time AS the exigencies of the
service permitted. In order, however, to
bring intelligence to bear up the casting
of this great gun, it will 6e advisable to
understand something of the accessories
to which it is indebted for it's perfection.
The buildings, cranes. furnaces, pat
terms, flask iand lathe, had to be entirely
new-cOnstructed, in order to accommO-
date themselves to the immense size of the
gun.
The model of the 2O-inch is projec-
ton of the first 15-inch gun. The length
of the first casting is 26 feet its maxi
mum diameter 66 inches; and its weight
100000 pounds The length of the fin
ished gun will be 20 feet 3 inches; it's
maximum diameter GA inches; and it's
weight $4,000 pounds The diameter
of the first casting at the muzzle will be
four feet, and that of the finished gun at
the muzzle "a inches. The whole length
of the bore is 210 inches.
The gun will be hung on trunnions
placed over its centre of gravity, and al
lowing no preponderance. This mode of
hanging guns, introduced by Major Rod
man renders their manipulation in service
much easier than when great prepon-
derance is at the breech.
The metal from which the gun is manu-
featured is from the pure Juniata iron,
from the Bloomfield Juniata, and Rodnlan
furnaces now in the hands Of the prOprie-
tor of the Fort Pitt foundry. The gun is
constructed altogether on the Rodman
plan. The public, however, so greatly
prefer practice to principle, that we APP
pend compressed description of the pro-
cess adopted.
Consists of flask (made in four pieces,
bolted and clamped firmly together), and
of the sand which it contains, and which
forms the matrix of the gun. The flask
weighs twenty-eight tons and the sand
ten. The mould is formed by placing the
flask over wooden pattern of tle exact
size of the rough casting, and then ram
o ming the sand between the pattern and
the flask The pattern is then withdrawn,
the mould is ''slicked'' or smoothed over,
and then washed with black coating
made of ground coal. The mound is then
placed in an oven, and baked until it is of
the size of an ordinary soft brick. One of
the finest specimens of hard labor and
good workmanship that we have ever wit
messed is that presented by the immense
mass of sand, which, in the case of the
2O.inch, was ra mined, finished up, blacked,
and placed in the oven by ten men, in
twenty hours! The flask being removed
from its ovens, and clamped firmly to-
gether, is placed vertically in pit, made
specially for itsreception. Thus disposed,
the muzzle end of the mould is on level
with the mouth of the pit, and the centre
line of the gun is perpendicular
The pit which receives the flask is
twenty eight and half feet deep, and
fourteen feet in diameter. Inside it, near
the bottom, great bars radiate like the
spokes OF wheel. Underneath these
tues, on the outside, communicates a
draught. Another fue, leading from the
top OF the pit, carries off the smoke. The
object of both the flues and the bars ia to
maintain strong fire around the flask.
This is one of the objects of the Rodman
process of casting guns.