out, nothing is left with which to combat the upward
vertical thrusts of the air. To attempt to run before the wind is to
court positive disaster, as the wind is certain to gain the mastery.
Once the airship loses steering way and is rendered uncontrollable it
becomes the sport of the forces of Nature, with the result that
destruction is merely a matter of minutes, or even seconds.

Every navigator who knows the North Sea will support these conclusions.
Squalls and blizzards in winter, and thunderstorms in summer, rise
with startling suddenness and rage with terrific destructive fury.
Such conditions must react against the attempt of an aerial invasion
in force, unless it be made in the character of the last throw by a
desperate gambler, with good fortune favouring the dash to a certain
degree. But lesser and more insignificant Zeppelin raids are likely
to be somewhat frequent, and to be made at every favourable climatic
opportunity.

CHAPTER VII. AEROPLANES OF WAR

Owing to the fertility of inventors and the resultant multiplicity of
designs it is impossible to describe every type of heavier-than-air
machine which has been submitted to the exacting requirements of
military duty. The variety is infinite and the salient fact has already
been established that many of the models which have proved reliable and
efficient under normal conditions are unsuited to military operations.
The early days of the war enabled those of doubtful value to be
eliminated, the result being that those machines which are now in
use represent the survival of the fittest. Experience has furthermore
emphasised the necessity of reducing the number of types to the absolute
minimum. This weeding-out process is being continued and there is no
doubt that by the time the war is concluded the number of approved types
of aeroplanes of military value will have been reduced to a score or
less. The inconveniences and disadvantages arising from the utilisation
of a wide variety of different types are manifold, the greatest being
the necessity of carrying a varied assortment of spare parts, and
confusion in the repair and overhauling shops.

The methodical Teuton was the first to grasp the significance of these
drawbacks; he has accordingly carried standardisation to a high degree
of efficiency, as is shown in another chapter. At a later date France
appreciated the wisdom of the German practice, and within a short time
after the outbreak of hostilities