He was busy for some time with his levers, and the smell of ozone reached Mrs. Baker's nostrils as she stared with horrified eyes at the animals. She blinked. The sparks crackled madly, the monkey mewed, the cat chattered. Were her eyes going back on her? She could see neither animal distinctly: they seemed to be shaking in some cosmic disturbance, and were but blurs. This illusion--for to her, it seemed it must be optical--persisted, grew worse, until the quaking forms of the two unfortunate creatures were like so much ectoplasm in swift motion, ghosts whirling about in a dark room. Yet she could see the cages quite distinctly, and the table and even the indicators of the scales. She closed her eyes for a moment. The acrid odors penetrated to her lungs, and she coughed, opening her eyes. * * * * * Now she could see clearly again. Yes, she could see a monkey, and it was climbing, quite naturally about its cage; it was excited, but a monkey. And the cat, while protesting mightily, acted like a cat. Then she gasped. Had her mind, in the excitement, betrayed her? She looked at Professor Burr. On his lean face there was a smile of triumph, and he seemed to be awaiting her applause. She looked again at the two cages. Surely, at first the cat had been in the right-hand cage, and the monkey in the left! And now, the monkey was in the place where the cat had been and the cat had been shifted to the left-hand cage. "So it was with Smith, when the alloys burned out," said Burr. "It is impossible to extract the ego or dissolve the atoms and translate them into radio waves unless there is a connection with some other ego and body, for in such a case the translated soul and body would have no place to go. Luckily, for you, madam, it was the man Smith who was killed when the alloys failed me. It might have been Allen, for he was the second pole of the connection." "But," she began faintly, "how can this mad experiment have anything to do with saving my boy?" He waved impatiently at her evident denseness. "Do you not understand? It is so I will save Allen, your son. I shall first switch our egos, or souls, as you say. Then switch the bodies. It must always take this sequence; why, I have not ascertained. But it always works thus." Mrs. Baker was terrified. What she had just seen, smacked of the blackest magic--yet a woman in her position must grasp at straws. The world blamed her son for the murder of Smith, a man Professor Burr had made use of as he might a guinea pig, and Allen must be snatched from the death house. "Do--do you mean you can bring Allen from the prison here--just by throwing those switches?" she asked. "That is it. But there is more to it than that, for it is not magic, madam; it is science, you understand, and there must be some physical connection. But with your help, that can easily be made." * * * * *