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Bishop, J. Leander (John Leander), 1820-1868 / A history of American manufactures from 1608 to 1860 : exhibiting the origin and growth of the principal mechanic arts and manufactures, from the earliest colonial period to the adoption of the Constitution ; and comprising annals of the industry of the United States in machinery, manufactures and useful arts, with a notice of the important inventions, tariffs, and the results of each decennial census
Volume 3 (1868)

Manufactures of Boston,   pp. 276-312 ff.

Page 281

United States Army. After having cast five 10-inch Guns in this way
satisfactorily, preparations were then made to also cast 15-inch Guns
after the same method, and the work on guns of this calibre was com-
menced in June, 1863. Forty tons of metal are required to cast a gun
of this size, and a description of the processes may interest our readers.
In the centre of the room is sunk a cylinder of three-quarter inch
iron, water tight, and twenty-five feet deep. On the inside is placed a
wall of brick 16 inches thick. The cylinder is thirteen feet four inches
in diameter.  In the centre of this is placed a heavy cast-iron flask
six feet six inches in diameter. Upon the inside of the flask is placed a
layer of clay and other materials, bearing in the centre the form of the
casting required. When this is made as smooth as possible, the core is
inserted, and suspended in its required position by a heavy iron frame
resting upon the top of the flask. This core-arbor is formed by a cast-
iron cylinder of 13 inches in diameter, turned and fluted on the outside.
Around it is wound a small rope, plastered with loam, about an inch
thick. This core-arbor is made perfectly water-tight, with the excep-
tion of having two orifices-one to force water in, the other to let it out.
The Cochituate water is discharged through the core at the rate of forty
gallons per minute.  The object is to cool the gun from the inside to the
outside, and prevent an unequal contraction of the metal. The utmost care
is required in all these operations, defects in which might produce disastrous
and fatal consequences. The metal is prepared in two air furnaces, each
.capable of melting 25 tons. When all is ready, and about 15 men are
placed in their required position, the order is given, the furnaces are
tapped, and the molten iron flows into the flask. One hundred and twelve
hours are required to cool the gun so that it can be removed. On ac-
count of the risk incident to the casting, spectators are seldom admitted
to the works during the operation.
The South Boston Iron Company have manufactured for the Govern-
ment since the commencement of the present rebellion an immense
amount of ordnance and projectiles. It has been remarked by those best
qualified to judge, that had it not been for the South Boston works and
the works at Pittsburg, a supply of the materials and enginery of war,
which was furnished promptly and continuously by them, could not have
been otherwise obtained in the United States in two years.
The present number of men employed in these extensive works is four
hundred, and gangs are kept working night and day. The same system,
adopted by Mr. Cyrus Alger, of retaining men through a series of years,
often keeping many on half-pay when their services were not needed, has
secured for this Company an unexcelled force of employees who fully
understand the requirement of every department of labor in which they
are employed.

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