"Thirty-six thousand amperes!" Marlin told her impressively. "That's a lot of stepping up. Eli claims his batteries are capable of supplying current for several months, and while I don't know their capacity, it must be considerable. Suppose most of this potential current was drained off by the shell of our vessel, acting like a Leyden jar or accumulator, and then released in one titanic discharge. Don't you see? This must have accomplished the near-impossible--the polarization of the repulsion plates, resulting in the anti-gravity reaction." "You sure deal out jawbreakers when you get started," Sally shrugged. "All right," he went on imperturbably. "The intense discharge probably lasted only a moment--but that was sufficient. It shot our sphere away from the earth as if it had been fired from a cannon--sent it with an initial momentum which took us far beyond Earth's attraction and must still be continuing undiminished in the vacuum of space." Sally yawned and rose. "What you need is a classroom," she said. "I'll pass the word along in case any of the rest feel the need of brushing up on their education." * * * * * Her departure scarcely disturbed Marlin's train of thought. His theory, of course, gave birth to other perplexing problems. How account for the fact that neither sphere nor passengers were crushed by the enormous acceleration? He had an answer for that one. Logically, he reasoned, they owed their salvation to the fact that they, too, were subject to the momentary repulsion of the activated plates. Repulsion hurled them violently away--acceleration pressed them back. The two forces practically cancelled out. Possibly the insulation on the upper surfaces of the plates gave acceleration a slight edge, causing the crushing sensation Marlin had felt at the onset of their flight. But the anti-gravity force was no longer in effect--probably had lasted not more than a few seconds. What had caused the plates to become imbued with an opposite force--an attractive force akin to gravity? To answer this, Marlin found himself seeking analogies in the realm of electrical phenomena. A magnet, he reflected, is a bar of iron in which the movements of the molecules are so organized as to keep the lines of their magnetic axis parallel--all the molecular north poles pointing toward the same end of the bar. It is accomplished by placing the bar in a larger magnetic field, and it is made permanent by tempering--which fixes the molecules in permanent alignment.