"Make it!" said Mr. Damon promptly. "Air pumps are cheap. Just carry one or two on board the aeroplane, and condense the air as you go along. That's a small detail that can easily be worked out. I leave that to you."
"I'd rather you wouldn't," said Tom. "That's the whole difficulty—compressing your air. Wait! I'll explain it to you."
Then the young inventor went into details. He told of the ponderous machinery needed to condense air to a form approximating water, and spoke of the terrible pressure exerted by the liquid atmosphere.
"Anything that you would gain by having a slow-speed motor and smaller propeller blades, would be lost by the ponderous air-condensing machinery you would need," Tom told Mr. Damon. "Besides, if you could surround your propellers with a strata of condensed air, it would create such terrible cold as to freeze the propeller blades and make them as brittle as glass.
"Why, I have taken a heavy piece of metal, dipped it into liquid air, and I could shatter the steel with a hammer as easily as a sheet of ice. The cold of liquid air is beyond belief.
"Attempts have been made to make motors run with liquid air, but they have not succeeded. To condense air and to carry it about so that propellers might revolve in it, would be out of the question."
"You think so, Tom?" asked Mr. Damon.
"I'm sure of it!"
"Oh, dear! That's too bad. Bless my overshoes, but I thought I had a new idea. Well, you ought to know. So Damon's Whizzer goes on the scrap heap before ever it's built. Well, we'll say no more about it. You ought to know best, Tom. I wasn't thinking of it so much for myself as for you. I thought you'd like some new idea to work on."
"Much obliged, Mr. Damon, but I have a new idea," said Tom.