His exploring fingers contacted a fragment of some sort--a pebble or hardened lump of clay. Detaching it from the surface, he fingered it exploringly. When his fingers relaxed, the lump escaped and instantly snapped back to the plate, as if held by a taut rubber band. He recovered the fragment and tried the same thing experimentally, with the same result. There was no mistake. Objects released below the anti-gravity plates dropped toward them, just as did objects released from above. If anything, the attraction of the underside was stronger. In point of fact, the supposed anti-gravity plates were gravity plates. Convinced of something he had vaguely suspected, Marlin retired to his usual vantage point--the observation scaffold--to think matters out. He was vaguely disturbed when Sally clambered up the ladder and joined him. "You're up to something?" she accused. "Tell Sally what it's all about." "I'd only bore you." "What's the difference? I'm bored anyway." She sat beside him on the edge of the platform, bare feet protruding from her threadbare slacks. Marlin was quite certain that she wouldn't resist if he put his arm around her, but he squelched any such impulse. Too many times he had seen DuChane's arm occupying that position. "All right," he observed. "You asked for it." He told her what he had discovered. "Well," she asked, "what of it?" "This is the way I'd explain it. I think the criticism of Thornboldt's principle, advanced by orthodox scientists, was probably justified. Such an enormous application of energy would be needed to effect the stress required for anti-gravity polarization, that it was a practical impossibility. Yet somehow this enormous power was generated for the brief moment which marked the plunge of our vessel into outer space." "I think we ought to christen the old ball," she remarked irrelevantly. "How about calling it what Bart suggested--the Thornboldt?" "I suppose the inventor is entitled to some credit," Marlin agreed absently. "But to figure this out: Let's assume a generator or storage battery capable of delivering current of one ampere strength for a hundred hours. Suppose it should release the same amount of current within a single hour. The strength of the current would obviously be multiplied a hundred times, wouldn't it? Suppose the same current were released in a single minute. It would be multiplied six thousand times. Suppose it were released in a second, what would be its strength?" "I'm no good at figures," replied Sally, fidgeting.