y in relation to the speed of the machine. Increased weight,
unless it were accompanied by a proportionate augmentation of power
in the motor, would react against the efficiency and utility of the
machine, would appreciably reduce its speed, and would affect its
climbing powers very adversely. In some quarters it was maintained
that as a result the machine would even prove unsuited to military
operations, inasmuch as high speed is the primary factor in these.

Consequently it was decided by the foremost aviating experts that
machines would have to be classified and allotted to particular spheres
of work, just as warships are built in accordance with the special
duty which they are expected to perform. In reconnaissance, speed is
imperative, because such work in the air coincides with that of
the torpedo-boat or scout upon the seas. It is designed to acquire
information respecting the movements of the enemy, so as to assist the
heavier arms in the plan of campaign. On the other hand, the fighting
corsair of the skies might be likened to the cruiser or battleship. It
need not possess such a high turn of speed, but must be equipped with
hard-hitting powers and be protected against attacking fire.

One attempt to secure the adequate protection against gun-fire from the
ground assumed the installation of bullet-proof steel plating, about one
fifth of an inch thick, below the tank and the motor respectively.
The disposition of the plating was such as to offer the minimum of
resistance to the air and yet to present a plane surface to the ground
below. So far as it went this protection was completely effective, but
it failed to armour the vital parts against lateral, cross and downward
fire while aloft. As the latter is more to be feared than the fire from
the ground, seeing that it may be directed at point blank range, this
was a decided defect and the armour was subsequently abandoned as
useless.

The only effective method of achieving the desired end is to armour the
whole of the carriage or fuselage of the adroplane, and this was the
principle adopted by the Vickers Company. The Vickers military aeroplane
is essentially a military machine. It is built of steel throughout.
The skeleton of the machine is formed of an alloy which combines the
qualities of aluminium and steel to ensure toughness, strength, and
lightness. In fact, metal is employed liberally throughout, except in
connection with the wings, which follow the usu