d French dirigible construction
up to 1912. The Clement Bayard was a simple non-rigid having four lobes
at the stern end to assist stability. These were found to retard
the speed of the airship, which in the second and more successful
construction was driven by a Clement Bayard motor of 100 horse-power at
a speed of 30 miles an hour. On August 23rd, 1909, while being tried for
acceptance by the military authorities, this vessel achieved a record
by flying at a height of 5,000 feet for two hours. The Astra-Torres
non-rigids were designed by a Spaniard, Senor Torres, and built by the
Astra Company. The envelope was of trefoil shape, this being due to the
interior rigging from the suspension band; the exterior appearance
is that of two lobes side by side, overlaid by a third. The interior
rigging, which was adopted with a view to decreasing air resistance,
supports a low-hung car from the centre of the envelope; steering is
accomplished by means of horizontal planes fixed on the envelope at the
stern, and vertical planes depending beneath the envelope, also at the
stern end.

One of the most successful of French pre-war dirigibles was a Clement
Bayard built in 1912. In this twin propellers were placed at the front
and horizontal and vertical rudders in a sort of box formation under the
envelope at the stern. The envelope was stream-lined, while the car of
the machine was placed well forward with horizontal controlling planes
above it and immediately behind the propellers. This airship, which
was named 'Dupuy de Lome,' may be ranked as about the most successful
non-rigid dirigible constructed prior to the War.

Experiments with non-rigids in Germany was mainly carried on by Major
Parseval, who produced his first vessel in 1906. The main feature of
this airship consisted in variation in length of the suspension cables
at the will of the operator, so that the envelope could be given an
upward tilt while the car remained horizontal in order to give the
vessel greater efficiency in climbing. In this machine, the propeller
was placed above and forward of the car, and the controlling planes were
fixed directly to the envelope near the forward end. A second vessel
differed from the first mainly in the matter of its larger size,
variable suspension being again employed, together with a similar
method of control. The vessel was moderately successful, and under Major
Parseval's direction a third was constructed for passenger carryin