“To our camp. Then I think I must take a few women and scout the edges of the sea.”

“We can do that now.”

The king giant laughed. “Our thanks, Louis, but my warriors will be in an ugly mood when they return. Naked, hungry, defeated. It may go better for them when they learn that I am gone for a few days. I am no god. A hero must have warriors happy with his rule. He cannot be fighting every waking hour.”

The lander cruised five miles up at just under sonic speed.

Thirteen thousand miles was no great distance for the lander. Louis’s caution irked the kzin. “Two hours and we can be dropping onto the floating city, or rising from underneath! One hour, without serious discomfort!”

“Sure. We’d have to go out of the atmosphere with the fusion drive blazing like a star, but sure. Remember how we reached Halrloprillalar’s floating jail? Upside down in midair, with the motors burned out of our flycycles?”

Chmeee’s tail thumped the back of his chair. He remembered.

“We don’t want to be noticed by any old machinery. The superconductor plague doesn’t seem to have got it all.”

Grassland gave way to patterns of cultivation, then to a watery jungle. Vertical sunlight reflected back at them from between the trunks of flowering trees.

Louis was feeling wonderful. He wouldn’t let himself see the futility of his war on the sunflower patch. It had worked. He had set himself a task; he had accomplished it with intelligence and the tools at hand.

The swamp seemed to go on forever. Once Chmeee pointed out a small city. It was difficult to see, with water half drowning the buildings, and vines and trees trying to pull them down. The architectural style was strange. Every wall and roof and door bulged outward a little, leaving the streets narrow in the center. Not built by Halrloprillalar’s people.

By midday the lander had traveled further than Ginjerofer or the king giant would travel in their lifetimes. Louis had been foolish to question savages. They were as far from the floating city as any two points on Earth.

The Hindmost called.

Today his mane was a swirling rainbow, dyed in streamers of primary colors. Behind him puppeteers flickered along lines of stepping discs, clustered at shop windows, brushed against each other without apology or resentment, all in a murmur of music with flutes and clarinets predominating: puppeteer language. The Hindmost asked, “What have you learned?”

“Little,” said Chmeee. “We have wasted time. There was certainly a great solar flare seventeen falans ago—about three and a half years—but we guessed that much. The shadow squares closed to protect the surface. Their guidance system must operate independently of the Ringworld’s.”

“We could guess that too. No more?”

“Louis’s hypothetical Repair Center is certainly inactive. This swamp below us was not designed. I imagine a major river silted up to block the outflow of a sea. We find a variety of hominids, some intelligent, some not. Of those who built the Ringworld we find no trace, unless they were Halrloprillalar’s ancestors. I am inclined to think they were.”

Louis opened his mouth … and glanced down at a threshold pain in his leg. He found four kzinti claws just resting on his thigh. He shut his mouth. Chmeee continued, “We have not met any of Halrloprillalar’s species. Perhaps they were never a dense population. We hear rumors of another race, the Machine People, who may rise to replace them. We go to seek them.”

“The Repair Center is inactive, yes,” the Hindmost said briskly. “I have learned much. I have put a probe to work—”

“You have two probes,” Chmeee said. “Use both.”

“I hold one in reserve, to refuel Needle. With the other I have learned the secret of the spill mountains. See—”

The far right screen showed a probe’s-eye view. It raced along the rim wall; passed something, too quick for detail; slowed, turned, moved back.

“Louis advised me to explore the rim wall. The probe had barely started its deceleration routine when it found this. I thought it worth investigating!”

There was a swelling on the rim wall—a tube hooked over the lip. It was molded, flattened against the rim wall, and was made of the same translucent gray scrith. The probe eased toward it until the camera was looking up into a pipe a quarter-mile across.

“Much of the Ringworld’s design shows a brute-force approach,” the Hindmost was saying. And the probe moved alongside the pipe, over the lip, and down the outer face of the rim wall to where the pipe disappeared into the foamed material that formed a meteor shield for the Ringworld’s underside.

“I see,” Louis said. “And it wasn’t working?”

“No. I tried to trace the pipe and had some success.”

The scene jumped. Now it showed dark racing motion as the probe cruised a good distance outward from the Ringworld. Inverted landscape passed above, seen by infrared light. The probe slowed, stopped, moved upward.

If a meteor struck the Ringworld, it had to fall first from interstellar space; and it struck with that velocity plus the Ringworld’s own seven hundred and seventy miles per second. A meteor had struck here. The plasma cloud had drawn a savage gouge across hundreds of miles of sea bottom, vaporizing the protective foam. There in the gouge was a length of pipe a few hundred feet in diameter. It led up into the sea bottom.

“A recycling system,” Louis murmured.

The puppeteer said, “Without some counterbalance to erosion, the Ringworld’s topsoil would all be in the sea bottoms in a few thousand years. I expect the pipes ran from the sea bottoms along the underside and up over the rim wall. They deposit sea-bottom sludge on the spill mountains. Much of the water would boil away in the near vacuum at the peak, thirty miles high. The mountain gradually collapses under its own weight. Material moves from the rim walls inward, carried by winds and rivers.”

Chmeee said, “Mere supposition, but plausible. Hindmost, where is your probe now?”

“I intend to bring it out from under the Ringworld and reinsert it into the rim transport system.”

“Do that. Does the probe have deep-radar?”

“Yes, but the range is short.”

“Deep-radar the spill mountains. The spill mountains are … perhaps twenty to thirty thousand miles apart? Thus we may find on the order of fifty thousand spill mountains along both rim walls. A handful of those would make a fine hiding place for the Repair Center.”

“But why should the Repair Center be hidden?”

Chmeee made a rude noise. “What if the subject races should revolt? What of an invasion? Of course the Repair Center is hidden, and fortified too. Search every spill mountain.”

“Very well. I will scan the starboard rim wall in one Ringworld rotation.”

“Scan the other rim afterward.”

Louis said, “Keep the cameras going too. We’re still looking for attitude jets … though I’m starting to think they had something else going.”

The Hindmost clicked off. Louis turned to the window. It had been tickling at his attention all along: a pale thread that curved along the edge of the swamp, straighter than a river. Now he pointed out the barely visible pair of dots moving along its length. “I think we need a closer look at that. Why don’t you take us down?”

It was a road. From a hundred feet up it was rough-surfaced, stony stuff: white stone poured in a stream. Louis said, “The Machine People, I presume. Shall we track those vehicles?”

“Let us wait until we are closer to the floating city.”

Giving up a present opportunity seemed silly, but Louis was afraid to object. The kzin’s tension was thick enough to smell.

The road avoided the low, wet areas. It seemed in good repair. Chmeee followed it at low speed, a hundred feet up.