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 this wonderful man who has such a wonderful scheme?'

'Oh, I forget his name,' I said. 'But the theory, as far as I can gather, is rather a good one. He can rise so quickly.'

'How?'

'Well,' I replied. 'From what I can hear, there is a kind of rotary wing—not a propeller and not a thing which can be classed as a helicoptic.'

Lionel Eastwell grew intensely interested in the new invention which everybody at the aerodrome was discussing.

'Yes,' he said. 'I follow. Go on, Claude. Tell me all you've heard about it. The whole thing sounds most weird and wonderful.'

'Well,' I said, 'from what I can find out, the machine is not designed to screw itself through the air in the direction of its axis, or, by pushing the air downwards, to impart upward motion to the structure, as a screw propeller in water imparts a forward motion to the vessel by pushing the water backwards. The biplane is designed to obtain by a rotary motion the same upward thrust in opposition to the downward pull of gravity as the flapping wings, and the passive outspread wings of birds, and to obtain it by the blades being projected through the air in such a manner as to extract and utilize the practically constant energy of the expansive force of the air.'

'By Jove!' my friend exclaimed, stirring himself in his bed. 'That theory is very sound indeed—the soundest I've ever heard. Who's invented it?'

'As I've told you, I've forgotten,' I replied. 'But