"It just doesn't look that much like the future," she said. "It's recognizable. I always thought the future would be so different, it wouldn't be recognizable. Particularly a thousand years in the future. But there are buildings, subways—I mean, why not matter transmitters?"

"Alexandria and this rail system are a lot older than other parts of the Stone. When you get around and see things in more detail, you'll notice big differences between our technology and this. Beside. . .” He paused. "There's history to consider. Delays. Handicaps. And holdovers."

"Which I'll know about soon enough."

"Right," Lanier said. "Did you feel any motion just now? Acceleration?"

She frowned. "No. But maybe we started out slowly—"

"The trains accelerate at four g's."

"Wait." She turned to a window and looked at the passing bars of white, then frowned. "Alexandria. . . I mean, it wasn't designed right."

Lanier regarded her patiently. She was supposed to be brilliant, but in many ways she was so young. Struggling to maintain her decorum as if she were a schoolgirl.

"The Stone has to accelerate and decelerate, right? Just like this train. But I don't feel any motion now, and. . . the chambers should have angled floors, to compensate for the thrust, for the wash of water in the lakes and ponds—higher walls on one side. Acceleration slosh. Angled walkways to compensate."

"There aren't any provisions for acceleration in the chambers," Lanier said.

"So they accelerated slowly?"

He shook his head.

"They had some way to compensate?"

"The sixth chamber," Lanier said. "But that's part of the big picture, too."

"You're making me sort everything out for myself."

"Whenever possible."

"As a test."

"No," Lanier said emphatically. "The Advisor said you can help us. I don't doubt that. But if this were a test, you'd be doing just fine." Though he had reservations.

The tunnel walls passed behind them and the train rushed into light. They passed over water, doing at least two or three hundred kilometers an hour. "In the elevated stretches, there are three rails under the cars, magnetic induction," Lanier said.

"Oh." She turned her attention to the sea, a uniform expanse of rippling blue-gray, stretching north to a bank of fog against the cap. Above the gray expanse she could see the chamber's arch, and to the northwest and northeast the distant edges of the fog bank, and a shoreline at three o'clock high.

About seven kilometers from the train, its lower extremity hidden in white mist, was the hexagonal top of an upright tower, perhaps fifty meters tall and half as broad. Another tower appeared only a kilometer or so distant, fully visible and mounted on a slender round pylon.

The fog rushed up to meet them, and suddenly, they were over land. Rich pine forest blurred beneath, appearing healthy—if slightly blue—in the tubelight.

"Fourth chamber was a recreation center, as near as we can tell," Lanier said. "And of course, a reservoir and air-purification system. There are four distinct islands here, each with a different habitat. There were underwater habitats, too—coral gardens, freshwater ponds and river systems. Resort, wildlife preserve, fish farm—it's all returned to an untended state, a bit wild but prospering."