[Illustration: Mr. Tedder felt an embarrassed flush coloring his cheeks as the figure of the girl undulated before his eyes....] Mr. Tedder yelped, and immediately regretted it. He'd had two beers three days before; could that bring on hallucination at this late date? But Honey had gone, taking the Ziegler coils with her. One terminal of the telegraph key was still connected to the plate on the spark coil, the other wire ended in a little knot of fused silver. No, this wasn't the effect that Doctor Ziegler had reported, not at all! * * * * * To cover his confusion Mr. Tedder began to talk. "There, you've just seen the Ziegler effect in action. Explain what you've just seen and you'll be famous among men." Indeed, the cerium-iron alloy bar had disappeared; but so had 20,000 cm. of No. 40 silver wire, silk-insulated. But the boys--except, of course, Stetzel and Guenther--hadn't noticed. Mr. Tedder glanced over his shoulder to the clock, saw that it would be fifteen minutes before the class would end, and made a quick decision in the interest of his sanity. "Class dismissed!" he said. There was a stupefied second while the news soaked into dormant nervous systems. Then the boys were shouting across the room, grabbing up books, and hurrying out into the hall to take noisy advantage of their moment of freedom. Stetzel and Guenther, as behooved the top pupils of the Class of '95, hurried up to Mr. Tedder to check their notes. "The symbol for cerium is 'Ce,' isn't it?" Stetzel asked. "Yes. But now...." "How did you do that, Mr. Tedder?" Guenther interrupted. "Do what?" Mr. Tedder glanced suspiciously at Guenther. Perhaps it hadn't been those two beers. "You had a woman dancing, right up where those solenoids were," Guenther said. "That's what I saw," Stetzel substantiated. "What a movie! She sure looked three-dimensional to me. Wow!" "Yes," Mr. Tedder said, canceling his decision of a moment before, to lay off beer. "That was just a little stunt I thought up to see how many of you were paying attention. New optical principle, you know. Now if you'll excuse me, I've got to get things ready for the next class. And wake up Norcross on your way out, will you?" Stetzel jarred Norcross from unconsciousness and walked out into the hall, talking and gesturing significantly with Guenther. Norcross unfolded himself slowly, glanced with a furtive eye toward Mr. Tedder and the empty bench-top, and walked rapidly out of the room, down the stairs, and into the school physician's office. Alone, Mr. Tedder frowned at the bereft lithium battery and telegraph key. He had pressed the key, closing the circuit, and there'd been a spurt of flame. A strange girl had appeared, dancing on the marble top of the demonstration bench. He'd never seen the woman before; a tall blonde wearing very little.... What the devil! There she was again.