The morning call., 1892-01-17
MODERN MORTARE,
The Time That It Takes to Cast One Of These
notwithstanding Process.

From o'clock in the morning until . 80 in
the afternoon workman sat in a niche in
the rear of the furnace in the foundry of the
South Boston Iron Works, and from time to
time he pulled out a brick in the furnace
wall and gazed at the mass of iron which
was slowly being fused. Just twenty-five
tons of iron were in the furnace. This iron
in another form was to be one Of the new
32-inch rihed mortars which are now being
made for the coast defense Of the United
States. The Notifications when complete
will require more than 500 of these mOrtars,
of which but seyenty-three are contracted
for.
The South Boston Iron Works has a con-
tract for fOrty-three and the Builders Iron
Foundry Of Providence contract for thirty.
The Providence contractors have fnishe
casting and are now assembling the mOrtars.
The Boston contractors cast the twenty
fifth mortar yesterday. In the workshops
are the big mortars in every stage of conf
pletiOn. from the rough casting down to the
nearly completed gun. The cost is $500
each. OF this the casting costs $3.50, tn e
steel $500 and the assembling $3.50,
This is exclusive of the carriage.
The casting of the gun is an interesting
United States Ordnance Department super
vises the work. In the center Of the fOun-
dry Is a big pit about sixteen feet deep,
which is lined with brick. A day or two
previous to the casting big flask is lowered
into the pit. This flask is in six sections of
iron, which is divided once longitudinally
and twice literally. In this flask. which is
perforated with hundreds of small holes
for the escape of the gas, is lining nine
inches thick Of molding sand baked hard.
The inner surface is coated with powdered
plumbago, or facing.
A The bottom of the pit under the center
OF the flask Is an iron pot about sixteen
inches in diameter which contains a layer
OF sand. The curvature of the pot is fol-
lowed in shape Exactly in the center OF
the flask is placed an arbor of cast iron
which is wound with rope covered with fine
clay and baked.
This arOor is hollow The arbor is futed
TO allow the gases to escape The rope is
gradually consumed in the casting, and it is
possible to withdraw the arbOr, leaving the
coating of clay in the interior TO protect the
bore of the gun.
In the center Of the arbor is placed an
iron pipe which extends nearly to the bot
tom. Such is, briefly, the method of east
ing. AT 2:50 O'clock yesterday afternoon
the molten metal in the furnace was at the
proper consistency for casting. Superin-
tendent Hunt was in charge He cast a
final glance around and ordered the men to
''let her come" Two men rammed bars Of
iron into the top of the furnace and worked
them back and forth, and the molten metal
flowed forth in a thin stream down the
trOughs, into the ladle and then to either
side of the flask and dropped to the bottom.
There was sizzling, swapping and sput-
tering of the iron. and as it disappeared in
the mold there was a regular Fourth of
| July display of stars and fireworks. The
workmen carefully scraped the Stag from
the metal and regulated the flow. In eX-
actly nine minutes the mold was full and
the big ladle was placed upright to hold the
excess of fl0w
Over the end OF the arbor was then placed
a big tripod, which has cap with screw
connection for base attachments. Then a
workman approached with q hose and
turned stream of cold water into the ar
hor. AS the water reached the bottom there
was a report like cannon, and all the sand
and refuse IN the arbOr was blown high in
the air. The cap was placed on the tripod
and the hose attached to the pipe on the ar
bOr Water at 40 degrees Fahrenheit was
turned on aud soon filled the arbor and
flowed away in another pipe. This is the
R0dman cold core casting system.
The object is to cool the gun from the in
side and keep the outside as hot as possible
until the bore is cold. This causes cOntrac-
ton as the layers of iron cool, each layer
being shrunk on the other, until the casting
is gradually compressed by a constant pres
sure from the material composing it. The
wood and coal in the pit is then fired and
| soon the flask is surrounded by a roaring
| hot fire. which tends 70 keep the outside Of
| the casting in afluld state. The first day
! the water flows into the arbor at the rate Of