National Republican., 1886-10-02
MAKING MAMMOTH GUNS.
Various Operations in Their Manutac-
ture from the pIt to tho CarriaRs.


Or steel provided with suitable loading and
firing devices, and mounted upon car
Ilapo. But the study OF the history Of the
guu shows that at every step In It's maui
iacturo great skill aud exceeding care wero
extrclsed, and colossal machinery, working
with exquisite precision, was employed.
From the first process, the making OF tho
lit and mould, TO the iual finishing, mis-
step Ia liable to destroy all the work, aud
theIzfofe long experience and the highest
skin are necessary to insure perfection. In
tho following article VIC have endeavOrel ID
plainly describe the various operations in
making u mammoth gun, from the pit to
tic carriage.
The South Boston Iron Works has minu-
factured ordnance and war material for the
United States government for upward OF
ifty years, and during the rebellion worked
night and day to keep up it4 supply for tue
war.
(Four engravlpgs, showing ordnance
machinery and the guns in process of con-
aifuCtiOp, and one view Of the 5itOu
Ireech.lOadDg rifle, mounted on pneu-
matte siCgo carriage Of tue ordnance PROV
ing grounds, accompany this article
No In an Interior view OF large orI-
nance foundry, where the 81 ton guns ar5
cast, the ground being broken away 50 as
TO show Esection Of the pit, which Is placel
IN the center OF the foundry. ON the right
are two SO-ton reverberatory furnaces for
melting the iron for the casting, and another
40-ton furnace Is on the left Of the pit.
The combined capacity OF these monster
furnaces is 1876 tOus. a trough or runner
leads from each furnace to q pool or basin
placed at the mouth Of tho pit, aul from
which short runner conveys the molten
lion 10 the mold.
The nit is 40 feet deep by Is feet In dlams.
ter, aud its brick walls arc foot thick Ia
the center Of the pit stands the gun flask,
which rests ON dry sand supported upon a
firm foundation Of masonry aud concrete.
Every precaution Is taken to prevent the
entrance OF water within the pit, since even
an extremely small quantity would ruin
The work. The lasks arc flanged sections
Of iron, which, when placed in position In
the pit, form u shell for supporting the
mold. The tasks are rammed, washed,
and dried before being lowered iuto the pit,
and are not touched after being placed In
position.
These TASKS, being called upon to sus-
tain a quantity OF melted iron weighing
from 1875 to 100 tons, and to resist pres
sure due to nearly 10 feet, are necessarily
made Of great strength. When casting on
July o, 1884, the TASKS broke and the Iron
flowed into and flied the bottom of the pit
The "cheese" thus formed was u feet
high, II feet in diameter, and weighed l3i
tons. IL was three months work to re
move this from the pit, and 1t was wedged
60 firmly that II required Il force OF 736 tons
TO start II from the bottom.
The upper end of the core arbor Is sup
ported by cast iron tripod or spider, rest
ing upon tho upper edge OF the top flask.
Tie lower end Of tho core arbor is stea LIED
by chaplet which 10 on the muZZle Of the
gun casting and beyond the end OF tn,
finished gun. Through the center OF the
nrbor passes pipe, which terminates neal
the lower end of the arbor. Water llOwt
through this pipe and up the arbor to al
outlet pipe at the top. The water is kep'
running at the rate OF forty gallons pei
minute, both before and during the casting
ard for two days after, thereby gradual!
cooling the interior OF the casting; the laye
Of metal next the core Is first cooled ant
solidifled, next the succeeding layer II
cooling shrinks and binds upon the first
aud so on throughout the mass, The (
terror being the last to acquire set.
There are three heavy cranes In this
foundry, having each lifting power oi
thirty tons. They are used principally TO
lowering the gun TASKS into the pit ant
itmoving them after the gun has been cast
The gun is hoisted from the pit by hydraulic
power or by a system OF lifting screw jacks
both contrivaDces having been used. Afte
the gun has been lifted from the pit 1t |
moved into the ordnance machine shops OF
rolls, much after the manner of moving /
~ inilinterior view OF the ordnance machIn
shop, showing one OF the flfty-four to
rifles in the process OF being pored in on
Of the one hundred ton lathes, Is Interest
ing. This gun is to have short steel tube
four inches thick, inserted from the breec
and extending little forward Of the trun
Dions. This tube is shrunk into the Dor
Of the gun, the latter being heated. Th
longitudinal sectional views, figure .
show this tube and its length and relatlv
thickness. The diameter OF the bore of tbl
gun is twelve inches and It's total lengtl
thirty feet. 1t will be fired with powde
charge Of 265 pounds OF brown coco
powder, and will throw an 800 pound sho
ten miles.
There could also be seen another 100-to
lathe IN the machine shop, with a 53-ton RID
in the stUge Of being turned. This gun ha
cast iron body weighing about 81 tons.
(made by Sir Joseph Whitworth, of Eng
laud), ia shrunk into the bore from the real
and extends into the gun for 1853 inches
Two layers Of steel hoops OF an averag
width Of II inches and q thickness Of
inches, 26 In number, aud about 40 inchC
in diameter, are shrunk on to the outside {
the cast iron body. The hoops are bore
four-huDdredths OF an inch smaller than th
outside diameter Of the cast iron body, an
are expanded by gas burners until they al
two-hundredths of an inch larger than th
body, and are then pushed up to place
Then q stream Of water is played on to th
hot ring until II cools. The ring then hug
the cast iron, and strengthens it. While th
ring is 'setting," 1O0-ton jack keeps II
position and close up to the preceding RIM
70 that there shall not be any space at th
Joint between any two rings exceedin
three thousandths Of an iuch. The diam,
ter Of the body OF this gun, when ready fc
the shrinking on Of the hoops, showed II
variation over two thousandths OF an incl
ana the ordnance officers consider II IL
finest and most accurate shrinking ever dor
In this country or abroad.
This gun will fire the same charges as I'll
54.ton rife. The diameter Of the bore
the same l12 inches), but 1t is two fe,
shorter. The gun, when finished. Is abo,
five feet In diameter.
The 12-inch breech-loading rifle is all Gu
iron;.,that is, It has no steel tubes or hoop
is riied with twist one turn In 1856 calibe
at origin to one turn in 40 calibers at mu
zle, and is mounted on Powlett pne
matte siege carriage, and there is one no
at the United States ordnance proviI
grounds at Sandy Hook, N. j. This rll
was mounted In June, 1885, and has bee
fired 1877 rounds with charges Of 265 pount
of powder and an 500 pound projectil
This is the best record known In this
foreign countries for a 12.inch rife vii
this weight OF powder and projectile.
l2.inch b. l.. steel rife, made by He
KIupp, has been fired 100 rounds I'll
mu2zle velocity Of the l2-inch gun'irC
rifle Is 1862 felt per second; penetration
LOCO yards, 90 inches Of armor, and rang
10 miles.
The Powlett carriage. on which this q
Is mounted, was made at the South BostC
hon works last autumn, and Is worked @
tirely by compressed air, This system
owned by the Pneumatic Gun CarriaI
Company, Of Washington, d, @. The rect
from this gun, equivalent to starting 8
pounds OF from with velocity OF 1852 fe
per second, is taken up entirely by Il