Jules Verne's Aeronef was merely
an idea, and one that could never be realised while Robur's
mysterious source of electrical energy remained unknown--as it still
does.

"Maxim's Aeroplane is, as you all know, also an unrealised ideal so
far as any practical use is concerned. He has succeeded in making it
fly, but only under the most favourable conditions, and practically
without cargo. Its two fatal defects have been shown by experience to
be the comparatively overwhelming weight of the engine and the fuel
that he has to carry to develop sufficient power to rise from the
ground and progress against the wind, and the inability of the
machine to ascend perpendicularly to any required height.

"Without the power to do this no air-ship can be of any use save
under very limited conditions. You cannot carry a railway about with
you, or a station to get a start from every time you want to rise,
and you cannot always choose a nice level plain in which to come
down. Even if you could the Aeroplane would not rise again without
its rails and carriage. For purposes of warfare, then, it may be
dismissed as totally useless.

"In this machine, as you see, I have combined the two principles.
These helices on the masts will lift the dead weight of the ship
perpendicularly without the slightest help from the side-planes,
which are used to regulate the vessel's flight when afloat. I will
set the engines that work them in motion independently of the others
which move the propellers, and then you will see what I mean."

As he spoke, he set one part of the mechanism working. Those watching
saw the three helices begin to spin round, the centre one revolving
in an opposite direction to the other two, with a soft whirring sound
that gradually rose to a high-pitched note.

When they attained their full speed they looked like solid wheels,
and then the air-ship rose, at first slowly, and then more and more
swiftly, straight up from the table, until it strained hard at the
piece of cord which prevented it from reaching the roof.

A universal chorus of "bravas" greeted it as it rose, and every eye
became fixed on it as it hung motionless in the air, sustained by its
whirling helices. After letting it remain aloft for a few minutes
Arnold pulled it down again, saying as he did so--

"That, I think, proves that the machine can rise from any position
where the upward road is open, and without the slightest assistance
of any apparatus. Now it