y metallic
angle-iron, plates, and bracing; this utilisation of metal is, however,
carried out very sparingly. The first vessel of this class was a huge
failure, while subsequent craft have not proved much more successful.

In fact, one of the largest German airships ever designed, L4, is, or
rather was, a Schutte-Lanz, with a capacity of 918,000 cubic feet, but
over 6,000 pounds lighter than a Zeppelin of almost similar dimensions.
I say "was" since L4 is no more. The pride of its creators evinced a
stronger preference for Davy Jones' Locker than its designed realm. Yet
several craft of this type have been built and have been mistaken for
Zeppelins owing to the similarity of the broad principles of design and
their huge dimensions. In one vital respect they are decidedly inferior
to their contemporary--they are not so speedy.

The most successful of the German lighter-than-air machines are those
known respectively as the semi rigid and non-rigid types, the best
examples of which are the Gross and Parseval craft. Virtually they are
Teutonic editions of the successful French craft of identical design by
which they were anticipated. The Lebaudy is possibly the most famous of
the French efforts in this direction. The gas-bag has an asymmetrical
shape, and is pointed at both ends, although the prow is blunter or
rounder than the stem. The gas-bag comprises a single chamber for the
inflating agent, the distended shape of the envelope being sustained by
means of an air-ballonet. By varying the contents of the latter through
the agency of a pump the tension of the gas in the lifting envelope can
be maintained, and the shape of the inflated balloon preserved under all
conditions.

Beneath the gas-bag is a long strengthened girder, and from this in turn
the car is suspended. It is the introduction of this rigid girder which
is responsible for the descriptive generic term of "semi-rigid." On the
other hand the "non-rigid" type may be roughly described as a pisciform
balloon fitted with propelling machinery, inasmuch as the car containing
the driving machinery is suspended from the balloon in the manner of
the car in the ordinary drifting vessel. So far as the French effort is
concerned the Bayard-Clement type is the best example of the non-rigid
system; it is represented in Germany by the Parseval class.

The Gross airship has been definitely adopted as a military machine
by the German authorities, and figures in the "M" class