, and it was
not until the last decades of the nineteenth century, when light
and powerful motors had been constructed, that the problem became
really practical of solution.
During the nineteenth century several airships were built in
France and innumerable experiments were carried out, but the
vessels produced were of little real value except in so far as
they stimulated their designers to make further efforts. Two of
these only will be mentioned, and that because the illustrations
show how totally different they were from the airship of to-day.
In 1834 the Compte de Lennox built an airship of 98,700 cubic
feet capacity. It was cylindrical in form with conical ends, and
is of interest because a small balloon or ballonet, 7,050 cubic
feet contents, was placed inside the larger one for an air
filling. A car 66 feet in length was rigged beneath the envelope
by means of ropes eighteen inches long. Above the car the
envelope was provided with a long air cushion in connection with
a valve. The intention was by compression of the air in the
cushion and the inner balloon, to alter the height of the
airship, in order to travel with the most favourable air
currents. The motive power was 20 oar propellers worked by men.
This airship proved to be too heavy on completion to lift its own
weight, and was destroyed by the onlookers.
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