This time there was absolutely no doubt as to the result. There
was a roar like a fifty-foot wind tunnel, and a mighty blast of cold air
swept out of that coil like a six-inch model of a Kansas cyclone. Every
loose piece of paper in the laboratory came suddenly alive and whirled
madly before the blast of air that had suddenly leaped out. Dr. Arcot
was forced back as by a giant hand; in his backward motion his hand was
lifted from the relay switch, and with a thud the circuit opened. In an
instant the roar of sound was cut off, and only a soft whisper of air
told of the furious blast that had been there a moment before.

The astonished physicist came forward and looked at the device a moment
in silence, while each of the other men watched him. Finally he turned
to his son, who was smiling at him with a twinkle in his eye.

"Dick, I think you have 'loaded the dice' in a way that is even more
lucrative than any other method ever invented! If the principle of this
machine is what I think it is, you have certainly solved the secret of a
sufficiently absorbing area for a solar engine."

"Well," remarked the elderly Morey, shivering a bit in the chill air of
the room, "loaded dice have long been noted for their ability to make
money, but I don't see how that explains that working model of an Arctic
tornado. _Burr_ it's still too cold in here. I think he'll need
considerable area for heat absorption from the sun, for that engine
certainly does cool things down! What's the secret?"

"The principle is easy enough, but I had considerable difficulty with
the application. I think it is going to be rather important though--"

"Rather important," broke in the inventor's father, with a rare display
of excitement. "It will be considerably more than that. It's the biggest
thing since the electric dynamo! It puts airplanes in the junk heap! It
means a new era in power generation. Why, we'll never have to worry
about power! It will make interplanetary travel not only possible, but
commercially economical."

Arcot junior grinned broadly. "Dad seems to think the machine has
possibilities! Seriously, I believe it will antiquate all types of
airplanes, prop or jet. It's a direct utilization of the energy that the
sun is kindly supplying. For a good many years now men have been trying
to find out how to control the energy of atoms for air travel, or to
release the energy of the constitution of matter.

"But why do it at all? The sun is d