m of an airship. Nor must one overlook
the circumstance that in such an engagement the Zeppelins would become
the prey of hostile aeroplanes. The latter, being swifter and nimbler,
would harry the cumbersome and slow-moving dirigible in the manner of
a dog baiting a bear to such a degree that the dirigible would be
compelled to sheer off to secure its own safety. Desperate bravery and
grim determination may be magnificent physical attributes, ut they
would have to be superhuman to face the stinging recurrent attacks of
mosquito-aeroplanes.

The limitations of the Zeppelin, and in fact of all dirigible aircraft,
were emphasised upon the occasion of the British aerial raid upon
Cuxhaven. Two Zeppelins bravely put out to overwhelm the cruisers and
torpedo boats which accompanied and supported the British sea-planes,
but when confronted with well-placed firing from the guns of the vessels
below they quickly decided that discretion was the better part of valour
and drew off. In naval operations the aeroplane is a far more formidable
foe, although here again there are many limitations. The first and most
serious is the severely limited radius of action. The aeroplane motor is
a hungry engine, while the fuel capacity of the tank is restricted. The
German military authorities speedily realised the significance of this
factor and its bearing upon useful operations, and forth with carried
out elaborate endurance tests. In numerable flights were made with the
express purpose of determining how long a machine could remain in the
air upon a single fuel supply.

The results of these flights were collated and the achievements of each
machine in this direction carefully analysed, a mean average drawn
up, and then pigeon-holed. The results were kept secret, only the more
sensational records being published to the world. As the policy of
standardisation in the construction of aeroplanes was adopted the radius
of action of each type became established. It is true that variations
of this factor even among vessels exactly similar in every respect are
inevitable, but it was possible to establish a reliable mean average for
general guidance.

The archives of the Berlin military department are crowded with facts
and figures relating to this particular essential, so that the radius of
action, that is the mileage upon a single fuel charge, of any class and
type of machine may be ascertained in a moment. The consequence is that
the military au