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the aeroplane for a considerable period： the upper reaches of the
air are its sanctuary。
Nor must the nocturnal activities of the Zeppelin be overlooked。
So far as night operations by these vessels are concerned； little
has leaked out； so that the possibilities of the airship in this
direction are still somewhat hypothetical。 The fact remains；
however； that it is night movements which perhaps are the most to
be dreaded by the enemy。 According to official German sources of
information the latest types of Zeppelins are engined by
〃noiseless〃 motors。 There is nothing remarkable in this feature；
since the modern motor…car virtually answers to this description；
although in this instance quietness is obtained for the most part
by recourse to the sleeve…valve engine。 Still； the ordinary
Otto…cycle internal combustion engine can be rendered almost
silent by the utilisation of adequate muffling devices； which； in
the Zeppelin； are more possible of incorporation than in the
aeroplane； because the extra weight imposed by this acquisition
is a minor consideration in comparison with the lifting power of
the vessel。
Night operations； however； have not proved eminently successful。
The very darkness which protects the aerial prowler also serves a
similar purpose in connection with its prey。 But aerial
operations under the cover of darkness are guided not so much by
the glare of lights from below as betrayal by sound。 The
difference between villages and cities may be distinguished from
aloft； say at 1；500 to 3；000 feet； by the hum which life and
movement emit； and this is the best guide to the aerial scout or
battleship。 The German authorities have made a special study of
this peculiar problem； and have conducted innumerable tests upon
the darkest nights； when even the sheen of the moon has been
unavailable； for the express purpose of training the aerial
navigators to discover their position from the different sounds
reaching them from below。 In other words； the corsair in the
skies depends more upon compass and sound than upon compass and
vision when operating after dark。 The searchlights with which
the Zeppelins are equipped are provided merely for illuminating
a supposed position。 They are not brought into service until
the navigator concludes that he has arrived above the desired
point： the ray of light which is then projected is merely to
assist the crew in the discharge of the missiles of destruction。
The Zeppelin； however； owing to its speed； both in the horizontal
and vertical planes； is essentially a unit for daylight
operations。 The other airships which Germany possesses； and
which for the most part are of the non…rigid type； are condemned
to daylight operations from the character of their design。 Owing
to their low speeds they may be dismissed as impossible aerial
vessels for hazardous work and are not regarded by the German
authorities as all…round airships of war。
Craft of the air are judged in Germany from the one standard
only。 This may be a Teutonic failing； but it is quite in keeping
with the Teutonic spirit of militarism。 Commercialism is a
secondary factor。 To the German Emperor an airship is much what
a new manufacturing process or machine is to the American。
Whereas the latter asks； 〃How much will it save me on the
dollar？〃 to the War Lord of Germanyand an airship
notwithstanding its other recommendatory features is judged
solely from this standpointthe question is 〃What are its
military qualifications？〃
When the semi…rigid airship 〃V…I〃 was brought before the notice
of the German military department the pressing point concerning
its military recommendations arose at once。 The inventor had
foreseen this issue and was optimistic。 Thereupon the
authorities asked if the inventor were prepared to justify his
claims。 The retort was positive。 Forthwith the Junkers decided
to submit it to the test。
This ship is of quite a distinctive type。 It is an aerial
cruiser； and the inventor claims that it combines all the
essential qualifications of the Zeppelin and of the competitors
of the latter； in addition to the advantage of being capable of
dissection； transportation in parts； and rapid re…erection at any
desired spot。 The length of the vessel is about 270 feet；
maximum diameter approximately 42 feet； and capacity about
300；000 cubic feet。 The outstanding feature is a rigid
keel…frame forming a covered passage way below the envelope or
gas…bag； combined with easy access to all parts of the craft
while under way； together with an artificial stiffening which
dispenses with the necessity of attaching any additional cars。
The frame is so designed that the load； as well as the ballast
and fuel tanks； may be distributed as desired； and at the same
time it ensures an advantageous disposition of the steering
mechanism； far removed from the centre of rotation at the stern；
without any overloading of the latter。
The lifting part of the airship comprises a single gas bag fitted
with two ballonets provided to ensure the requisite gas…tension
in the main envelope； while at the same time permitting； in times
of emergency； a rapid change of altitude。 Self…contained blowers
contribute to the preservation of the shape of the envelope； the
blowers and the ballonets being under the control of the pilot。
Planes resembling Venetian blinds facilitate vertical steering；
while the suspension of the keel is carried out in such a manner
as to secure uniformity of weight upon the gas bag。 The
propelling power comprises two sets of internal combustion
engines； each developing 130 horse…power； the transmission being
through rubber belting。 The propellers； built of wood； make 350
revolutions per minute； and are set as closely as possible to the
centre of resistance。
But the most salient characteristic of this machine is its
portability。 It can be dismantled and transported by wagons to
any desired spot； the suspension frame being constructed in
units； each of which is sufficiently small to be accommodated in
an ordinary vehicle。 Upon arrival the parts may be put together
speedily and easily。 The authorities submitted the airship to
exacting trials and were so impressed by its characteristics and
the claims of the inventor that undoubtedly it will be brought
into service during the present crisis。
At the same time the whole faith of the German military staff so
far as airship operations are concerned； is pinned to the
Zeppelin。 Notwithstanding its many drawbacks it is the vessel
which will be used for the invasion of Great Britain。 Even the
harbour question； which is admitted to be somewhat acute； has
been solved to a certain degree。 At strategical points permanent
harbours or airship sheds have been established。 Seeing that the
airships demand considerable skill in docking and undocking； and
that it is impossible to achieve these operations against the
wind