ffect of gravity and our weight thus becomes approximately the same as
it is on Earth. Such garments are worn by all prospectors and other
visitors to Vulcan."

"How come the neutro-beams?" asked Luke.

They are used only here in the Workshop and they operate the same as the
neutro-broadcast from the bastion, the only difference being that the
broadcast blankets an area of about two miles in all directions. In both
cases vibratory ether waves are sent out and these are of such frequency
and wave form as to neutralize the anti-gravity energies originating in
our capsules. They render our suits useless, but those of the guards are
provided with insulating coverings which block off the waves and thus
permit their own garments to function even when the neutro-broadcast is
in operation."

"Smart guys," commented Luke. "Too smart. How the devil we gonna get
away, then? They'll send out the alarm and----"

"Ah, that is where we fool them, Fenton. With the radium."

"Radium!"

* * * * *

"Yes, didn't you know? This ore we mine here contains a higher
percentage of that valuable element than any on Earth or Mars. Its
emanations, together with certain atmospheric gases of Vulcan, are what
cause X.C.--a swift destruction of tissue in the lungs and other vital
organs. And this concentrate"--Fuller waved his hand toward the rows of
tubes before him--"is most highly radioactive of all the products of the
Workshop. That is why the sealed cell is so very dangerous to work in.
But it is this radioactive salt that gives us the means for escape----"

Both men turned quickly to their labors on hearing the footsteps of the
guard.

"My suit is already prepared," continued Fuller, when the eye had gone
from the peephole. "Now to prepare yours. I discovered that this
radioactivity can be used to defeat the purpose of the neutro-rays as
well or better than the regular insulation, which, of course, we can not
obtain. That is why I wanted to be in the sealed cell for a time. We
merely pack a quantity of the radioactive salt around the capsules in
the lining of our garments, and the radium emanations continue the
excitation of the tiny atomic generators even under the influence of the
neutralizing vibrations. Do you follow me?"

"Yes."

Luke did comprehend, even though the technical explanation was beyond
his understanding. They would be able to defy this terrible gravity of
Vulcan. They could