The Ringworld Engineers

high enough to rise above the water; undersea canyons showing as ridges five and six miles high.

What was above them now — a pebbled roof, dark even under light amplification, that seemed obtrusively close even though it was three thousand miles above — should be the Map of Kzin. The computer said it was. Kzin must have been tectonically active when the Map was carved. The sea beds bulged strongly; the mountain ranges were deep and sharp of outline.

Louis could identify nothing. Foam-shrouded contours weren’t enough. He needed to see sunlight patterns and yellow-and-orange jungle. “Keep the cameras rolling. Are you getting a signal from the lander?”

From his post at the controls the Hindmost turned one head back. “No, Louis, the scrith blocks it. Do you see the nearly circular bay, there where the big river ends? The great ship is moored across its mouth. Nearly across the Map, the Y-shape where two rivers join — that is the castle where the lander now rests.”

“Okay. Drop a few thousand miles. Give me an overview… or underview.”

Needle sank beneath its carved roof. The Hindmost said, “You made this same tour in the Lying Bastard. Do you expect to find changes now?”

“No. Getting impatient?”

“Of course not, Louis.”

“I know more than I did then. Maybe I’ll pick up details we missed. Like — what’s that, sticking out near the south pole?”

The Hindmost gave them an expanded view. A long, narrow, utterly black triangle with a textured surface, it dropped straight down from the center of the Map of Kzin. “A radiator fin,” the puppeteer said. “The antarctic must be kept refrigerated, of course.”

The Ringworlders were utterly bewildered. “I don’t understand,” Harkabeeparolyn said. “I thought I knew some science, but… what is it?”

“Too complicated. Hindmost—”

“Luweewu, I am not a fool or a child!”

She couldn’t be much over forty, Louis thought. “All right. The whole point is to imitate a planet. A spinning ball, right? Sunlight falls almost level at the poles of a spinning ball, so it’s cold. So this imitation world has to be cooled at the poles. Hindmost, give us more magnification.”

The fin’s textured surface became myriad adjustable horizontal flaps, silver above, black below. Summer and winter, he thought; and he heard himself say, “I can’t believe it.”

“Luweewu?”

He spread his hands helplessly. “Every so often I lose it. I think I’ve accepted it all, and then all of a sudden it’s too big. Too tanj big.”

Tears were brimming in Harkabeeparolyn’s eyes. “I believe it now. My world is an imitation of a real world.”

Louis put his arms around her. “It’s real. Feel this? You’re as real as I am. Stamp your foot. The world is as real as this ship. Just bigger. Way way bigger.”

The Hindmost said, “Louis?”

A bit of telescope work had found him more fins, smaller ones, around the Map’s perimeter. “Naturally the arctic regions must be cooled too.”

“Yah. I’ll be all right in a minute. Take us toward Fist-of-God, but take your time. The computer can find it?”

“Yes. Might we find it plugged? You said that the eye storm has been plugged or repaired.”

“Plugging Fist-of-God wouldn’t be easy. The hole’s bigger than Australia, and clear above the atmosphere.” He rubbed his closed eyes hard.

I can’t let this happen to me, he thought. What happens is real. What’s real, I can manipulate with my brain. Tanj, I should never have used the wire. It’s screwed up my sense of reality. But… cooling fins under the poles?

They were out from under the Map of Kzin. Deep-radar showed nothing of pipes beneath the contoured sea bottoms. Which must mean that the meteor shielding was foamed scrith. The pipes had to be there, or else flup would fill the ocean beds.

Those ridges on the Ringworld’s underside — those long, long undersea canyons. A dredge in each of the deepest canyons, an outlet at one end: you could keep the whole ocean bed clear.

“Veer a little, Hindmost. Take us under the Map of Mars. Then under the Map of Earth. It won’t take us too far out of our way.”

“Nearly two hours.”

“Risk it.”

Two hours. Louis dozed in the sleeping field. He knew that an adventurer snatches sleep when he can. He woke well ahead of time, with sea bottom still gliding past above Needle’s roof. He watched it slow and stop.

The Hindmost said, “Mars is missing.”

Louis shook his head violently. Wake up! “What?”

“Mars is a cold, dry, nearly airless world, isn’t it? The entire Map should be cooled, and desiccated too, somehow, and raised nearly above the atmosphere.”

“Yah. All of that.”

“Then look up. We should be beneath the Map of Mars. Do you see a fin far larger than that beneath the Map of Kzin? Do you see a nearly circular cavity bulging twenty miles inward?”

There was nothing above their heads but the inverted contours of a sea bottom.

“Louis, this is disturbing. If our computer memory is failing us… ” The Hindmost’s legs folded. His heads dipped downward, inward.

“The computer memory is fine,” Louis said. “Relax. The computer’s fine. See if the ocean temperature is higher above us.”

The Hindmost hesitated, half into fetal position. Then, “Aye, aye.” The puppeteer busied himself at the controls.

Harkabeeparolyn asked, “Do I understand you? One of your worlds is missing?”

“One of the smaller ones. Sheer carelessness, my dear.”

“These aren’t balls,” she said thoughtfully.

“No. Peeled like a round fruit, the peel spread flat.”

The Hindmost called, “The temperatures in this vicinity vary. Ignoring the regions around fins, I find temperatures from forty to eighty degrees Fahrenheit.”

“The water should be warmer around the Map of Mars.”

“The Map of Mars is not in evidence, and the water is not warmer.”

“Wha… at? But that’s weird.”

“If I understand you — yes, there is a problem.” The puppeteer’s necks arched out and curved around until he was looking into his own eyes. Louis had seen Nessus do that, and wondered if it was puppeteer laughter. It could be concentration. It was making Harkabeeparolyn queasy, but she couldn’t seem to look away.

Louis paced. Mars had to be refrigerated. Then where?…

The puppeteer whistled an odd harmonic. “The grid?”

Louis stopped in midstride. “The grid. Right. And that would mean… futz! That easy?”

“We make progress of sorts. Our next move?”

They’d learned a good deal, looking at undersides of worlds. So — “Take us on to the Map of Earth, basement level, please.”

“Aye, aye,” said the Hindmost. Needle continued to spinward.

So much ocean, Louis thought. So little land. Why had the Ringworld Engineers wanted so much salt sea in two single bodies? Two for balance, of course, but why so large?

Reservoirs? Partly. Preserves for the sea life of an abandoned Pak world? A conservationist would call that praiseworthy; but these were Pak protectors. Whatever they did was done for the safety of themselves and their blood descendants.

The Maps, Louis thought, were a superb piece of misdirection.