Zeppelin
resulted in disaster to the craft before she took to the air, while
the smaller craft carried out upon far less ambitious lines were
not inspiritingly successful. Latterly the non-rigid system has been
embraced exclusively, the craft being virtually mechanically driven
balloons. They have proved efficient and reliable so far as they go, but
it is the personal element in this instance also which has contributed
so materially to any successes achieved with them.

But although Great Britain and France apparently lagged behind the
Germans, appreciable enterprise was manifested in another direction.
The airship was not absolutely abandoned: vigilance was maintained for
a superior type of craft. It was an instance of weighing the advantages
against the disadvantages of the existing types and then evolving for a
design which should possess the former without any of the latter. This
end appears to be achieved with the Astra type of dirigible, the story
of the development of which offers an interesting chapter in the annals
of aeronautics.

In all lighter-than-air machines the resistance to the air offered
by the suspension ropes is considerable, and the reduction of this
resistance has proved one of the most perplexing problems in the
evolution of the dirigible. The air is broken up in such a manner by
the ropes that it is converted into a brake or drag with the inevitable
result that the speed undergoes a severe diminution. A full-rigged
airship such as the Parseval, for instance, may present a picturesque
appearance, but it is severely unscientific, inasmuch as if it were
possible to eliminateor to reduce the air-resistance offered by the
ropes, the speed efficiency might be raised by some sixty per cent and
that without any augmentation of the propelling effort. As a matter
of fact Zeppelin solved this vexatious problem unconsciously. In his
monster craft the resistance to the air is reduced to a remarkable
degree, which explains why these vessels, despite all their other
defects are able to show such a turn of speed.

It was this feature of the Zeppelin which induced Great Britain to
build the May-fly and which likewise induced the French Government to
stimulate dirigible design and construction among native manufacturers,
at the same time, however, insisting that such craft should be equal at
least in speed to the Zeppelins. The response to this invitation was the
Spiess, which with its speed of 45 miles per ho