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 fight unhampered; walk, or run--to meet these mysterious friends of Fuller's. The flashlights and the broadcast would be useless against them. The lanky scientist outlined the further details of his plan in swift whispers while he worked with the energizing capsule of Luke's garment. * * * * * Actual escape was surprisingly easy. They waited until the labor period was finished, when Chan Dai, the yellow-skinned guard, came to unlock the door. As agreed, Tom Fuller came out first and Luke held back, dragging his feet and cursing softly to himself. "What'd you say?" the guard snarled.