Heineman had limited the tuberider's speed to nine kilometers per second. Something in the tuberider's construction caused a violent shudder beyond that.

Lanier lay awake, restless, strapped to his reclined seat and staring up at the softly glowing orange light overhead. Heineman was breathing steadily across the aisle from him; the women slept behind a curtain Carrolson had rigged across the middle of the cabin. Carrolson snored faintly. From Farley he heard nothing.

Sexual passion had seldom dominated Lanier; his drives were normal enough, but he had always been able to ignore them, or control them in inappropriate situations. His two-year celibacy on the Stone had been less a hardship for him than it might have been for others. Nevertheless, he had never been hornier in his life than he was at this peaceful moment.

Despite the advantages, he had always felt faintly shamed of his lack of masculine anguish, as if it made him some sort of cold fish. Now the passion was upon him with a vengeance. It was all he could do to keep from stealing back through the curtain and fondling Farley. The desire was both funny and agonizing. He felt like a pubescent teenager, sweaty with need and unsure what to do about it.

The psychiatrists in his head worked overtime. Death, said the Freudian, only strengthens our desire to procreate—

So he lay sleepless, erect, unable to think clearly and refusing to masturbate. The very idea was ridiculous. He hadn't masturbated in well over a year, and never except in complete privacy.

Did the others feel this way? Heineman certainly never let on. Not once, in fact, had Lanier ever heard Heineman make a sexual comment except in the most isolated and theoretical sort of joking.

Did Farley feel this way?

Just as a test, one hand reached up to pull aside the thin thermal blanket covering him. He forced the hand to pull it back. Madness.

Finally, after an eternity, he slept.

At 100,000 kilometers, the V/STOL's forward-looking radar reported a massive obstruction ahead in the corridor. Heineman searched the corridor bore-hole science records for any echoes from such a distance and found none. "Looks like the physics people just shot a radar beam along the singularity," he said. "And what we're looking at now is a circular wall with a gap in the middle."

The wall obstructed passage to a height of twenty-one kilometers, leaving a hole in the middle about eight kilometers across. The plasma tube and singularity were not interrupted.

"Let's pass through and see what's on the other side," Lanier suggested. "Then we'll decide where we want to come down."

At a mere six thousand kilometers per hour, Heineman eased the tuberider down the singularity. The wall was a dirty bronze color, smooth and featureless. As they approached the hole, Carrolson trained a telescope on the wall's upper surface—with some difficulty.