oplane.

This vulnerability of the essential feature of the flying machine is a
decisive weakness, and exposes the aviator to a constant menace. It
may be quite true that less than one bullet in a thousand may hit the
machine, but when the lucky missile does find its billet its effect is
complete. The fact must not be overlooked that the gunners who work the
batteries of anti-aircraft guns are becoming more and more expert as a
result of practice, so that as time progresses and improved guns for
such duty are rendered available, the work of the aviator is likely to
become more dangerous and difficult. Experience has proved that the high
velocity gun of to-day is able to hurl its projectile or shell to an
extreme height--far greater than was previously considered possible--so
that considerable discretion has to be exercised by the airman, who
literally bears his life in his hands.

Although elaborate trials were carried out upon the testing ranges with
the weapons devised especially for firing upon flying machines, captive
balloons being employed as targets, the data thus obtained were neither
conclusive nor illuminating. The actual experiences of airmen have given
us some very instructive facts upon this point for the first time.

It was formerly held that the zone of fire that is to be considered as
a serious danger was within a height of about 4,500 feet. But this
estimate was well within the mark. Airmen have found that the modern
projectiles devised for this phase of operations are able to inflict
distinctly serious damage at an altitude of 9,000 feet. The shell itself
may have but little of its imparted velocity remaining at this altitude,
but it must be remembered that when the missile bursts, the contents
thereof are given an independent velocity, and a wide cone of
dispersion, which is quite sufficient to achieve the desired end,
inasmuch as the mechanism of the modern aeroplane and dirigible is
somewhat delicate.

It was for this reason that the possibility of armouring the airship was
discussed seriously, and many interesting experiments in this field were
carried out. At the same time it was decided that the armouring
should be effected upon lines analogous to that prevailing in warship
engineering. The craft should not only be provided with defensive but
also with aggressive armament. This decision was not viewed with general
approbation. It was pointed out that questions of weight would arise,
especiall