“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.
Once they passed a handful of buildings, the biggest of which seemed to be a chemical plant. Several times they watched boxy vehicles pass below them. They were seen only once. A box stopped suddenly, and humanoid shapes spilled out, ran in circles, then produced sticks which they pointed at the lander. A moment later they were out of sight.
There were great pale shapes in the wet jungle. They couldn’t be glacier-scoured boulders; not here. Louis wondered if they might be tremendous fungi. He stopped wondering when he saw one move. He tried to point it out to Chmeee. The kzin ignored him.
The road curved away to antispinward as it approached a range of craggy mountains; it jogged through a notch in the range, rather than carving its own path, then jogged right to run alongside the swamp again.
But Chmeee swerved left and accelerated. The lander streaked along the portward side of the range, trailing a plume of fire. Abruptly the kzin spun the lander around, braked, and set down at the foot of a granite cliff.
He said, “Let us step outside.”
The scrith shell of the mountain would block the Hindmost’s microphones, but they’d feel still safer outside the lander. Louis followed the kzin.
The day was bright and sunny — too bright, as this arc of the Ringworld approached its nearest point to the sun. A stiff warm wind was blowing. The kzin asked, “Louis, were you about to tell the Hindmost of the Ringworld engineers?”
“Probably. Why not?”
“I assume we’ve come to the same conclusion.”
“Doubtful. What would a kzin know of Pak protectors?”
“I know everything in the records of the Smithsonian Institute, what little there is. I have studied the testimony of the asteroid belt miner, Jack Brennan, and holos of the mummified remains of the alien Phssthpok and of the cargo pod from his ship.”
“Chmeee, how did you get hold of that stuff?”
“Does it matter? I was a diplomat. The existence of the Pak has been a Patriarch’s Secret for generations, but any kzin who must deal with humans is required to study the records. We learn to know our enemy. I may know more of your ancestry than you do. And I surmise that the Ringworld was built by Pak.”
Six hundred years before Louis Wu’s birth, a Pak protector arrived in Sol system on a mission of mercy. It was through this Phssthpok, via the Belter Jack Brennan, that historians learned the rest of the story.
The Pak were native to a world in the galactic core. They lived their lives in three stages: child, breeder, protector. The adults or breeders were just intelligent enough to swing a club or throw a stone.
In middle age, if they lived long enough, Pak breeders developed a compulsion to gorge on the plant called tree-of-life. A symbiotic virus in the plant triggered the change. The breeder lost its gonads and teeth. Its skull and brain expanded. Lips and gums fused into a hard, blunt beak. Its skin wrinkled and thickened and hardened. Its joints became enlarged, offering a larger moment arm to the muscles, increasing their strength. A two-chambered heart developed in the groin.
Phssthpok came tracking a Pak colony ship that had reached Earth more than two million years earlier.
The Pak were in a constant state of war. Previous colonies to nearby worlds in the galactic core had always been overrun by subsequent waves of ships. Perhaps that was the reason this ship had come so far.
The colony was large and well-equipped, and guided by beings tougher and smarter than humans. It had failed nonetheless. Tree-of-life grew in Earth’s soil, but the virus didn’t. The protectors had died out, leaving a lost population of Pak breeders to fend for themselves… and leaving records of a cry for help that had crossed thirty thousand light-years to the Pak home world.
Phssthpok found those records in an ancient Pak library. And Phssthpok crossed thirty thousand light-years, all alone in a slower-than-light craft, seeking Sol system. The resources that built that craft, in knowledge and minds and materials, were resources Phssthpok had conquered and held by war. His cargo pod was jammed with tree-of-life roots and seeds, and bags of thallium oxide. His own research had discovered the need for that unusual soil additive.
It might have occurred to him that the breeders would mutate.
Among the Pak a mutant stood no chance. If the children smelled wrong to their protector forefathers, they were killed. On Earth — perhaps Phssthpok counted on a lower mutation rate, this far from the savage cosmic-ray density among the core suns. Perhaps he took his chances.
The breeders had mutated. By Phssthpok’s time they showed little resemblance to the Pak breeder — barring certain changes at middle age, when the production of eggs stopped in females, and when both sexes showed wrinkling of skin, lost teeth, swelling of joints, and a restlessness and dissatisfaction that was all that remained of the hunger for tree-of-life. Later in life, heart attacks would result from the lack of the second heart.
Phssthpok learned none of this. The rescuer died almost painlessly, with no more than a suspicion that those he intended to rescue had become monsters, and had no need of him at all.
Such was the tale that Jack Brennan told to United Nations representatives before his disappearance. But
