plain a little bit to the poor goon who's
designing this flying battlewagon? How did you get a heat beam?"

Arcot grinned. "Simple. We use a small atomic cavity radiator at one end
of which is a rough relux parabolic filter. Beyond that is a lux metal
lens. The relux heats up tremendously, and since there is no polished
relux to reflect it back, the heat is radiated out through the lux metal
lens as a powerful heat beam."

"Okay, fine," said Fuller. "But stop springing new gadgets on me, will
you?"

"I'll try not to," Arcot laughed. "Anyway, let's get on to the main
power plant. Remember that our condenser coil is a gadget for storing
energy in space; we are therefore obliged to supply it with energy to
store. Just forming the drive field alone will require two times ten to
the twenty-seventh ergs, or the energy of about _two and a half tons_
of matter. That means a whale of a lot of lead wire will have to be fed
into our conversion generators; it would take several hours to charge
the coils. We'd better have two big chargers to do the job.

"The controls we can figure out later. How about it? Any suggestions?"

"Sounds okay to me," said Morey, and the others agreed.

"Good enough. Now, as far as air and water go, we can use the standard
spacecraft apparatus, Fuller, so you can figure that in any way you want
to."

"We'll need a lab, too," Wade put in. "And a machine shop with plenty of
spare parts--everything we can possibly think of. Remember, we may want
to build some things out in space."

"Right. And I wonder--" Arcot looked thoughtful. "How about the
invisibility apparatus? It may prove useful, and it won't cost much.
Let's put that in, too."

The apparatus he mentioned was simply a high-frequency oscillator tube
of extreme power which caused vibrations approaching light frequency to
be set up in the molecules of the ship. As a result, the ship became
transparent, since light could easily pass through the vibrating
molecules.

There was only one difficulty; the ship was invisible, all right, but it
became a radio sender and could easily be detected by a directional
radio. However, if the secret were unknown, it was a very effective
method of disappearing. And, since the frequency was so high, a special
detector was required to pick it up.

"Is that all you need?" asked Fuller.

"Nope," said Arcot, leaning back in his chair. "Now comes the kicker. I
suggest that we make the hull of foot-thick lux met