the weapons throw a one-pound shell and are closely
similar to the pom-pom which proved so effective during the South
African war. Machine guns also have been extensively adopted for this
duty by all the combatants, their range of approximately 2,000 yards and
rapidity of fire being distinctly valuable when hostile aircraft descend
to an altitude which brings them within the range of the weapon.

The greatest difficulty in connection with this phase of artillery,
however, is not so much the evolution of a serviceable and efficient
type of gun, as the determination of the type of projectile which
is likely to be most effective. While shrapnel is employed somewhat
extensively it has not proved completely satisfactory. It is
difficult to set the timing fuse even after the range has been found
approximately, which in itself is no easy matter when the aircraft is
moving rapidly and irregularly, but reliance is placed thereon in the
hope that the machine may happen to be within the cone of dispersion
when the shell bursts, and that one or more of the pieces of projectile
and bullets may chance to penetrate either the body of the airman or a
vital part of the mechanism.

It is this uncertainty which has led to a preference for a direct
missile such as the bullet discharged from a machine gun. A stream of
missiles, even of rifle calibre, maintained at the rate of some 400
shots per minute is certain to be more effective, provided range and aim
are correct, than shrapnel. But the ordinary rifle-bullet, unless the
objective is within very close range, is not likely to cause much harm,
at least not to the mechanism of the aerial vessel.

It is for this reason that greater attention is being devoted,
especially by the French artillerists, to the Chevalier anti-aircraft
gun, a weapon perfected by a Swiss technician resident in Great Britain.
It projects a formidable missile which in fact is an armour-piercing
bullet 1/2- to 3/4-inch in diameter. It is designed for use with an
automatic machinegun, which the inventor has devised more or less upon
the well-known French system. The bullet has a high velocity--about
2,500 feet per second--and a maximum range of 6,000 to 8,000 feet at
the maximum elevation. Should such a missile strike the motor or other
mechanism of the vessel it would wreak widespread havoc, and probably
cause the machine to come to earth. This arm has been designed for the
express purpose of disabling the aeroplane,