"What?" asked Tom with a smile.
"It's a Whizzer," said the eccentric man. "Bless my gold tooth! but that is the best name I can think of for it. And, really, the propeller I'm thinking of inventing does whiz around."
"But are you going to use a tractor or pusher type?" Tom wanted to know.
"It's a combination of both," answered Mr. Damon. "As it is now, Tom, you have to get an aeroplane in pretty speedy motion before it will rise from the ground, don't you?"
"Yes, of course. That's the principle on which an aeroplane rises and keeps aloft, by its speed in the air. As soon as that speed stops it begins to fall, or volplane, as we call it."
"Exactly. Now, instead of having to depend on the speed of the aeroplane for this, why not depend on the speed of the propeller—in other words, the whizzer?"
"Well, we do," said Tom, a bit puzzled as to what his friend was trying to get at. "If the propeller didn't move the airship wouldn't rise—that is, unless it's of the balloon type."
"What I mean," said Mr. Damon, "is to have an aeroplane that will move in the air the same as a boat moves in the water. You don't have to get the propeller of a boat racing around at the rate of a million revolutions a minute, more or less, before your boat will travel, do you? If the engine turns the screw, or propeller, just over say fifty times a minute you would get some motion of the boat, wouldn't you?"
"Why, yes, some," admitted Tom.
"And what causes it?" asked Mr. Damon, anticipating a triumph.