on within, and contains openings in the
roof and at the eaves for the escape of the smoke, a very large number
of barrels being proved at once.

The barrels are subjected to two provings. In the first, they are loaded
with a double charge of powder and two balls, thus subjecting them to a
far greater strain than they can ever be exposed to in actual service.
In the second proving, only the ordinary charge is used.

The interior of the proving-house is very happily arranged for the
purpose to which it is put. On the right-hand end of the building as you
enter, and extending across it, is a platform of cast-iron, containing
grooves in which the muskets are placed when loaded. A train of
gunpowder is then laid on the back side of this platform, connecting
with each barrel, and passing out through a hole in the side of the
building near the door. A bank of clay is piled up on the opposite side
of the room, into which the balls are thrown. Only one fatal accident
has occurred at the armory during the last two years, and this occurred
in the proving-house. When the muskets are brought in, they are placed
upright in frames, which, when full, are laid down upon the platform.
Five barrels are placed in a frame, and these five exploded while the
man was putting them in the proper position for laying them down, and
ten balls were plunged into him. No satisfactory explanation could ever
be obtained of the cause of the premature explosion.

About one per cent. of the barrels burst under this trial, although
under the old process of welding there was a loss of nearly two per
cent., or one in sixty.

The pieces that fail are all carefully examined, to ascertain whether
the giving-way was owing to a defect in the rolling, or to some flaw or
other bad quality in the iron. The appearance of the rent made by the
bursting will always determine this point. The loss of those which
failed from bad rolling is then charged to the operative by whom the
work was done, at a dollar for each one so failing. The name of the
maker of each is known by the stamp which he put upon it at the time
when it passed through his hands. As the workman gets but four cents for
rolling a barrel, he loses the work done upon twenty-five for each one
that fails through his negligence. The justice of this rule will be
apparent, when it is taken into account that that amount of cost has
been expended upon the barrel prior and subsequent to the work done by
the rolle