The elastic resistance of the gun to tangential rupture over the
powder chamber is computed by Claverino and kindred formulas to be
54,000 lb. per square inch.
[Illustration: THE ARMY 8 INCH STEEL GUN WITH CARRIAGE.]
The breech mechanism is modeled after the De Bange system. The block
has three smooth and three threaded sectors, and is locked in place by
one-sixth of a turn of a block, and secured by the eccentric end of a
heavy lever, which revolves into a cut made in the rear breech of the
gun. The gas check consists of a pad made of two steel plates or cups,
between which is a pad of asbestos and mutton suet formed under heavy
pressure. The rifling consists of narrow grooves and bands, 45 of
each. The depth of the groove is six one-hundredths of an inch.
Although the gun is designed for a charge of 100 pounds, it is
believed that it can be increased to 105 pounds without giving
dangerous pressure, and the intention is to increase the charge to
that amount when the new powder is received from Du Pont.
The following is a very full synopsis of the official report of the
preliminary firings--13 rounds--with this gun:
The first seven rounds were fired with German cocoa powder, which was
received from Watervliet Arsenal. There were two kinds of cartridges,
one kind weighing 85 pounds, and having 30 grains in each layer, the
other weighing 100 lb.
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