[Illustration: FIG. 1.--SINGLE BARREL GARDNER MACHINE GUN.]

The mechanism by which the various functions of loading, firing, and
extracting are performed is contained in a rectangular gun metal case,
varying in dimensions with the number of barrels in the arm. In the
single barrel gun the size of this case is 14 inches in length, 51/2
inches in depth, and 21/2 inches in width. The top of the box is hinged,
so that easy access can be had to the mechanism, which consists of a
lock, the cartridge carrier, and the devices for actuating them. In the
multiple barrel guns, the frames which, with the transverse bar at the
end, hold the barrels in place, form the sides of the mechanism chamber,
in the front end of which the barrels are screwed. The mechanism is
actuated by a cam shaft worked by a hand crank on one side of the
chamber. By this means the locks are driven backward and forward,
the latter motion forcing the cartridges into place, and the former
withdrawing the empty cartridge case after firing. The extractor hook
pivoted to the lock plunger rises, as the lock advances, over the rim of
the case, but is rigid as the lock is withdrawn, so that the action is
a positive one. The cartridges, which are contained in a suitable
frame attached to the forward part of the breech chamber, pass through
openings in the top plate of the latter, an efficient distribution being
secured by means of a valve having a transverse motion. Each cartridge
as it falls is brought into the axis of the barrel and the plunger,
while the advance motion of the lock forces them into position. In the
five-barrel gun illustrated by Fig. 3 the cartridge feeder contains 100
cartridges, in five Vertical rows of 20 cartridges each, and these are
kept supplied, when firing, from supplementary holders. Fig. 1 shows the
portable rest manufactured by the Gardner Gun Company. It consists of
two wrought iron tubes, placed at right angles to each other; the front
bar can be easily unlocked, and placed in line with the trail bar, from