a tall, hawk-nosed man Don classified on no evidence at all as a Shakespearean actor. All had been on the train. He didn't see Geneva Jervis anywhere.

An improvised speaker's table had been set up at one end of the room, near the door to the kitchen. A heavy-set man sat at the table talking to Mrs. Garet, the professor's wife.

"The stoutish gentleman next to Mother is the president of Cavalier," Alis said. "Maynard Rubach. When you talk to him be sure to call him Doctor Rubach. He's not a Ph.D. and he's sensitive about it, but he did used to be a veterinarian."

They sat down near the big table and Mrs. Garet smiled and waved at them. Mayor Civek came in through the kitchen door, licking a finger as if he'd been sampling something on the way, and sat down next to Mrs. Garet.

At that moment Don's stomach gave a hop and he felt blood rushing to his head. Others also had pained or nauseous expressions.

"Ugh," Alis said. "Now what?"

"I'd guess," Don said when his stomach had settled back in place, "that we've stopped rising."

"You mean we've gone as high as we're going to go?"

"I hope so. We'd run out of air if we went much higher."

Professor Garet came in presently, looking pleased with himself. He nodded to his wife and the men next to her and cleared his throat as he looked out over the room.

"Altitude 21,500 feet," he announced without preamble. "Temperature sixteen degrees Fahrenheit. From here on out—" he paused, repeated "out" and chuckled—"it's going to be a bit chilly. Those of you who are inadequately clothed will see my wife for extra garments. I believe you have been comfortably housed and fed. There will, of course, be no charge for these services while you are the guests of the Cavalier Institute of Applied Sciences. Thank you. I now present Mr. Hector Civek, the mayor of Superior, who will answer any other questions you may have."

Don looked at Alis, who shrugged. The conductor stood and opened a notebook which he consulted. "I have a few questions, Mr. Mayor. These people have asked me to speak for them and there's one question that outweighs all the others. That is—are you going to take us back to Earth? If so, when? And how?"

Civek cleared his throat. He took a sip of water. "As for the first question—we certainly hope to take you and ourselves back to Earth. I can't answer the others."

"You hope to?"

"Earnestly. I turn blue easily myself, and I'm as anxious as you are to get back. But when that will be depends entirely on circumstances. Circumstances, uh, beyond my control."

"Who's controlling them, then? Your friend with the whiskers?"

Professor Garet smiled amiably and patted his beard. The portly Maynard Rubach got up and Civek sat down.

"I am Dr. Maynard Rubach, president of Cavalier. I must insist that in common decency we all refrain from personal references. Mr. Civek has done his best to give you an explanation, but of course he is a layman and, while he has many excellent qualities, we cannot expect him to be conversant with the principles of science. I will therefore attempt to explain.

"As you know, science has been aware for hundreds of years that the Earth is a giant magnet...."

Don saw Geneva Jervis. She was at the kitchen door beyond the speaker's table.

"... the isogenic and the isoclinic ..."

The red-haired Miss Jervis saw Don now and put her finger to her lips.

"... an ultimote, which is simultaneously an integral part of ..."

Now the redhead was beckoning to him urgently. He excused himself to Alis, who frowned when she saw the other girl; then he went back of the speaker's table ("... 1,257 tenescopes to the square centimeter ...") into the kitchen. Jen Jervis was by now at the far end of it, motioning him to hurry up.

"I've found something," she said. She was wearing a shapeless fur coat, apparently borrowed.

"Come on. You'll have to see it."

"All right, but why me?"

"Aside from myself you seem to be the only one from the train with any gumption. I know you've been spying around doing things while everybody else sat back and waited for deliverance. Though I can't say I admire your choice of companions. That tawdry blonde—"

"Now, really, Miss Jervis!"

"Tawny, then; sometimes I mix up my words."

"I'll bet."

She led him out the back door and across the frozen ground past several buildings. They reached what once must have been an athletic field.

"At the far end," she said. "Come on."

"Where were you when your boy friend and his daredevil aces came over?"

"I saw them."

"Did they see you?"

"None of your business."

He shrugged. They were at a section of the grandstand at the end of the field. Jen Jervis indicated a door and Don opened it. It led to a big room under the stands. "What does this remind you of?" she asked.

Don looked blank. In the dim light he could see some planking, a long-deflated football, ancient peanut shells and an empty pint bottle. "I don't know. What?"

"Stagg Field? At the University of Chicago? Under the stands where they first made an atomic pile work?" She looked at him with the air of an investigator hot on the scent.

He shrugged. "Never been there. So what?"

"It's a pattern. This is where they've hidden their secret."

"It looks more like the place a co-ed and her boy friend might go to have a little fun. In warmer weather, of course."

"Oh!" she said. "You're disgusting! Look over there."

He looked, wondering what made this young attractive woman hypersensitive on the subject of sex. This was the second time she'd blazed up over nothing. What he saw where she pointed was a door at a 45-degree angle to the ground, set into a triangular block of concrete. "Where does that go?" he asked.

"Down," she said as they walked toward it. "And there's some machinery or something down there. I heard it. Or maybe I only felt the vibrations. It throbs, anyway."

"Probably the generator for the school's lighting system. Did you go down and look?"

"No."

"All right, then." He opened the door. "Down we go."

At the bottom of a flight of steps there was a corridor lit by dim electric light bulbs along one wall. The corridor became a tunnel, sloping gradually downward. They had been going north, Don judged, but then the tunnel made a right turn and now they were following it due east. "I don't hear any throbbing," he said.