Lanier raised his eyebrows and nodded. "Please don't take it personally."

So he's under strain, she thought. Well, so am I. Only he's had time to get used to it. If you can ever get used to something like the library. . . or the Stone itself. Then again, there's almost certainly more. . . .

She had the sudden vision of a maze of chalkboards waiting for her in the seventh chamber, filled with wandering mathematicians working on some grand, unified problem. Over them all, on a huge video screen, the Advisor watched patiently, like God. Lanier was her avatar.

"Rimskaya's half Russian," Lanier continued. "His grandmother was a widower and an immigrant and her name was applied on the U.S. entry papers to her son, as well. He speaks Russian like a native. Sometimes he acts as interpreter between the Russians and us."

The train's hum increased in pitch and they plunged into the fourth chamber's northern cap.

The fifth chamber was darker than the previous sections she had visited. A canopy of flat gray clouds painted the cylinder's upper atmosphere, cutting out half the tubelight. Beneath the clouds was a Wagnerian landscape of barren mountains, resembling ragged lumps of anthracite mixed with dark-rainbowed hematite. Between the mountains were rusty abyssal valleys, cut by waterfalls feeding into quicksilver rivers. The mountains toward the middle of the chamber floor were startling in their contortions—arches, giant rugged cubes, broken-tipped pyramids and causeways of irregular slab steps.

"What in hell was this?" she asked.

"A kind of open pit mine, we think. Our two geologists—you met Robert Smith, he's one—speculate that when the chambers were hollowed out, the fifth wasn't finished off. They left it for raw material. And the Stoners used it. These are the scars."

"Perfect for fans of old horror movies," Patricia said. "Can't you just see Castle Dracula here?"

They said nothing throughout the short trip down the next tunnel into the sixth chamber. As the train's hum decreased in pitch and the tunnel dark brightened, Lanier stood and said, "End of the line."

The lower terminal was a cavernous construct of unpainted slabs of reddish concrete and mottled gray-and-black asteroid rock. The platform was marked with faint lines, as though long winding queues had once formed there.

"This was a worker's station once," Lanier said. "When they modified the sixth chamber, this served as a debarkation point. Six hundred years ago, perhaps."

"How long has the Stone been deserted?"

"Five centuries."

They walked up a ramp into a building constructed mostly of thick transparent panels, giving an excellent view of the sixth chamber.

The valley floor was layered with gigantic inert mechanical forms, cylinders and cubes and stacks of circular plates laid on edge, resembling a monstrous circuit board. Just outside the terminal building, a row of spherical tanks marched off to a distant wall. The wall was at least a hundred meters high, and the tanks half that in diameter. Below this level of the terminal, between the spheres and a parallel row of cylinders resting on their sides, was an immense gully filled with glistening water. The channel was lined with pipe ends and cyclopian pumping apparatus. Over it all, thick black clouds floated in clumps, dropping curtains of rain and flurries of snow. Somewhere was a constant pulsing, less heard then felt, like the infra-sound beats of moving mountains or the grinding of distant sea bottoms.