The Harbor supervisor spread his empty hands, speaking only to Muub. "My idea is straightforward and I don't need to send pigskins flying around to describe it. I say we stick to what we know. I say we extend the Spine... but build it as long as we need it to be, down into the underMantle."

Seciv Trop rubbed his chin. "Well, that has the merit of familiarity, as you say. The wooden Spine would need protecting against dissolution in the underMantle, but we could use superconducting coils to achieve that, as we do now... But what an awesome undertaking it would be. I doubt if such a Spine could sustain its structural integrity on the lengthscale required. And it might affect the stability of the City itself. Could the anchor-bands sustain our position, here at the Pole, with such a counterweight?"

Muub was shaking his head. "Hosch, we can't conceivably spare the resources for this. You must know the timber convoys from the Crust have dried up since the Glitch, so we're not getting the wood. And we haven't the manpower to spare, in any case..."

"Besides," Dura said, "what if a Glitch hit? The Spine would be so fragile it would be destroyed in moments."

Hosch folded his arms and crossed his legs, turning his wiry body into a ball of finality. "Then it's impossible. We may as well stop wasting our time and tell Hork so."

Muub turned to him. "Frankly, Hosch, I won't be sorry if that is our conclusion. I'd rather not waste any more time and effort on this fool's errand than I have to."

"Oh, no." Seciv Trop's creased face showed irritation. "We haven't reached such a conclusion at all. We've merely eliminated possibilities. And we do, perhaps, have some of the elements of a workable solution."

Muub looked sour, and he pulled at a thread in his robe. "Go on."

"First, we know that this hypothetical device - this new, free-floating Bell - will need a protective magnetic field, to keep it from dissolution, and some means of propulsion. It will have to be self-sustaining; our traditional methods cannot be extended to such depths, so we've ruled out supply from the City. So the device would have to carry a simple turbine to generate a protective field."

"How would it move?" Dura asked. "I thought you said that jetfarts couldn't work."

"And so they couldn't," said Seciv. "But there are other means of propulsion..."

"Waving," said Farr, his round face animated. "What about that? Maybe we could make a Bell that could swim freely, a Bell that could Wave."

"Exactly." Seciv nodded, looking pleased. "We could haul ourselves along the Magfield, exactly as we do when we Wave in the Air. Well done, young man."

Muub pulled at his lower lip. "But maybe the Magfield doesn't penetrate the underMantle."

"We believe it does," Seciv said. "The underMantle and the Sea are permeated by charged particles - protons, electrons and hyperons - which sustain the Magfield."

Hosch sneered. "What would we do, attach a pair of false legs to the back?"

Farr - whose imagination seemed to have been caught - said excitedly, "No, you'd Wave using coils of superconductor. Like the anchor-bands. You could move them from inside the Bell, and..."

"Good thinking once more," Seciv said smoothly. "But you could go a little further. It wouldn't be necessary to move the coils themselves, physically; it is the movement of the current within them that could generate forward motion."

Muub was nodding slowly. "I see. So you'd make the current flow back and forth."

"Have it alternate. Exactly. Then the coils could be fixed rigidly to the hull. And, of course, this design would have a certain economy: the craft's propulsion system would be one and the same as the magnetic shielding system." He frowned. "But we would still face the problem of the excessive heat in the interior of the craft generated by a nuclear-burning turbine in an enclosed s.p.a.ce..."

Hosch looked reluctant to speak, as if, Dura thought, he genuinely hated to contribute anything positive. "But you wouldn't need to use nuclear burning," he said at last. "Anything to power the turbine would be sufficient... maybe even human muscles."

"No, I fear our muscles would be too feeble for such a task. But we could could use the power of animals - a team of pigs, harnessed to some form of turbine - yes, indeed!" He laughed and clapped Adda on the back, sending the old man spinning slowly like a bandaged fan. "So it seems after all that we will be riding pigs to the Core!" use the power of animals - a team of pigs, harnessed to some form of turbine - yes, indeed!" He laughed and clapped Adda on the back, sending the old man spinning slowly like a bandaged fan. "So it seems after all that we will be riding pigs to the Core!"

Adda steadied himself, grinning widely.

Muub looked around the group. "I don't believe it." He sounded disappointed. "I think we've come up with something we could build... something that might actually work."

Seciv pulled at his chin; Dura had never seen hands so bony and delicate. "We should build a prototype - there may still be unforeseen problems with the design. And, of course, once the descent begins the craft will encounter conditions we can only guess at."

"And then," Dura said, her spine p.r.i.c.kling and cold, "there are the Colonists. In fact, the mission will be a failure if it doesn't encounter the Colonists. What then?"

"What indeed?" Seciv echoed gravely.

Muub ran a hand over his bald head. "d.a.m.n you. d.a.m.n all of you. You've succeeded too well; I can't justify reporting to Hork that this idea of his is impossible." He eyed the Harbor supervisor. "Hosch, I want you to take charge of the design and construction of a prototype."

Hosch glared back resentfully, his thin face livid.

Muub said icily, "Call on these upfluxers, and you can have some of Seciv's time. As for labor, use some of your workers from the Harbor. But keep it simple and cheap, will you? There's no need to waste more of our energy on this than we have to." He turned in the Air, dismissing them. "Call me when the prototype's ready."

The Human Beings, arms loosely linked, followed Muub and the others slowly out of the Stadium.

"So," Adda said. "A chance to confront G.o.ds from the past."

"Not G.o.ds," Dura said firmly. "Even the Xeelee aren't G.o.ds... But these Colonists could be monsters, if they exist. Remember the Core Wars."

Adda sniffed. "This d.a.m.n fool expedition will never get that far anyway. This Waving Bell will be crushed."

"Perhaps. But you needn't be so stuffy, Adda. I know you enjoyed playing with ideas, back there. You have to admire the imagination, the spirit of these City folk."

"Well, what now?" Adda asked. "Do you want to find your friend Ito?"

"Later... I have something to do first. I need to find someone - the daughter of a friend, from my ceiling-farm. A friend called Rauc."

Adda thought about that. "Does the girl know what's become of her mother?"

"No," Dura said quietly. "I'm going to have to tell her."

Adda nodded, his crumpled face expressionless, seeming to understand.

And one day, Dura thought, Dura thought, I will have to go to the upflux forests, and tell Brow... I will have to go to the upflux forests, and tell Brow...

She glanced at Farr. The boy's eyes were fixed on an indefinite distance, and his face was blank. She felt as if she could read his mind. Humans were going to build a ship to find the Colonists. Humans were going to build a ship to find the Colonists. It was indeed an idea full of wonder... deep inside herself, too, she found, there was a small spark of awe. It was indeed an idea full of wonder... deep inside herself, too, she found, there was a small spark of awe.

And Farr was young enough to relish a ride.

But Adda was right. It was an utterly deadly prospect. And surely, she thought, as Hork's "experts" on the Xeelee, at least one of the three Human Beings would be a.s.signed to the voyage, if it were ever made...

She held Farr's arm tight and pulled herself closer to him, determined that Farr should never make the journey he was dreaming of.

18.

WAKEFULNESS INTRUDED SLOWLY on Mur.

Slowly, in shreds and shards, he became aware of the rustle of the Crust-trees, the tired stink of his own body, the endless yellow glow of the Air pushing into his closed eyecups. He'd used a few loops of frayed rope to bind himself loosely to a branch of an outlying tree, and now he could feel the undeniable reality of the ropes as they dug into the thin flesh of his chest and thighs.

Then the pain started.

His stomach, empty for so long, seemed to be slowly imploding, filling the center of his body with a dull, dragging ache. His joints protested when he began to stir - stiff joints were a wholly unexpected side-effect of hunger, reducing his movements on bad days to those of an old man - and there was a sharp sheet of pain stretched around the inside of his skull, as if his brain were pulling away from the bone.

He jammed his eyes closed and wrapped his arms around himself, feeling his own bony elbows digging into his ribs. How strange it was that he had never slept more deeply in his life than in these impossibly difficult times. While waking life had become steadily more unbearable, sleep was ever more comfortable, seductive, a different realm in which his physical pain and mental distress dissolved.

If only I could stay there, he thought. he thought. How easy it would be never to wake up again... How easy it would be never to wake up again...

But already the pain had dug too far into his awareness for that option to be available today.

With a sigh he opened his eyes and probed at the cups with one finger, working at rims sharp with crusty sleep deposits. Then he clambered slowly out of his loose sling of ropes. The rest of the Human Beings - the other fourteen - were scattered across the lower rim of the forest, bound by similar loops of rope. Dangling there half-asleep they looked like the pupae of insects, deformed spin-spiders perhaps.

Mur dropped out of the forest, avoiding the eyes of those others who were awake.

He stretched, his muscles still aching from yesterday's Waving. He pulled a handful of leaf-matter from the tree, and then flexed his legs and Waved stiffly down into the Mantle. Perhaps twenty mansheights below the fringe of the forest ceiling he lifted his tunic and raised his legs to his chest. His hips and knees protested, but he grabbed his lower legs and pulled his thighs close to his stomach. At first his bowels failed to respond to this prompting - like the rest of his system his digestive and elimination processes seemed to be failing, slowly - but he persisted, keeping his arms wrapped around his legs.

At last his lower bowel convulsed, and - with a stab of pain which lanced through the core of his body - a hard packet of waste was expelled into the Air. He glanced down. The waste, floating down into the Mantle, was compact, too dark.

He cleaned himself with his handful of leaves.

Dia, his wife, came drifting down from the impromptu camp in the forest. As she descended, he saw how she was blinking away the remnants of sleep and compressing her eyecups against the brightness of the Air; but she was already - just moments after waking - squinting along the vortex lines into the South, toward the distant Pole, trying to a.s.sess how far they had come, how much further was left of this huge odyssey.

When she reached Mur she looked into his face, kissed him on the lips, and wrapped her arms around his chest. He folded his arms around her and rubbed her back. Through her shabby poncho he could feel the bones of her spine. They had nothing to say to each other, so they clung to each other, hanging in the silent Air, with the Quantum Sea spread below them.

Since Dura and the City woman had left in their Air-car - taking away the children, including their own Jai - the fifteen abandoned Human Beings had trekked across the Mantle toward the Pole. The slow pulsations of the vortex lines marked out the endless days of the journey. With no stores of food, the Human Beings were forced to follow the fringe of the Crust-forest; the leaves of the trees were scarcely nutritious, but they did serve to fool the body into forgetting its hunger for a while. Every few days their food ran out and they were forced to interrupt the march. There was some game to be had but the forest was unfamiliar, and the animals, still scared and scattered after the most recent Glitch, were wary and difficult to trap.

Without their own herd, the Human Beings were slowly starving to death. And on this hopeless trek, with its endless days of slow, painful Waving, the Human Beings were probably burning off their energy faster than they could replace it. Mur couldn't forget the richness of the "bread" Dura had brought to them, when she had come Waving out of the sky so unexpectedly with her startling stories of Cities in the Air.

Their progress around the Mantle's curve was imperceptible, a crushingly discouraging crawl. Every time he woke to another changeless Mantlescape Mur felt discouraged. And, even when the Pole was neared, the Human Beings would still have to cross the hinterland, the cultivated belt around the Pole. How would the inhabitants of those regions - themselves suffering after the Glitches - welcome this band of starving refugees as they came drifting beneath their ceiling-farms?

The logical thing for the Human Beings to do would be to give up this trek. Their best chance of survival would be to stay here, or even retreat a little further into the upflux, and try to establish a new home on the edge of the Crust-forest. Stop wasting their energies on this trek. They could build a new Net, establish a new herd of Air-pigs. They could even, he'd thought dizzily as he Waved across the silent Air, experiment with maintaining flocks of rays. The flesh of the ray was tough and not as palatable as Air-pig, but it softened when broiled using nuclear-burning heat; and the eggs were fine to eat and easy to store.

...But, of course, that wasn't possible; for their children had been taken from them, by well-meaning Dura, and transported to the South Pole. When he stared into the dull crimson glow of the Pole, in the far downflux, Mur felt as if a chain as long as a vortex line connected him directly to his child, a chain which dragged inexorably at his heart. Dura's action had surely been in the best interests of the children. But it left Mur knowing that his only chance of meeting his son again was to stay alive and to complete this trek, all the way to the City at the Pole.

He squeezed Dia once, and then they broke and prepared to return to the Crust-forest, to face the others and begin the day's work.

"Dia! Mur!" The voice, drifting down from the Crust-forest, radiated excitement.

Dia and Mur slowed their ascent, confused, and looked up. Philas was dropping toward them, her skinny legs pumping at the Air. When she reached the couple, she grabbed at their arms to stop herself.

Dia held Philas's shoulders. "What is it? What's wrong?"

Philas, panting, the bones of her face prominent under her tied-back hair, shook her head. "Nothing's wrong. But... look. Look down there." She pointed, down past their feet into the Mantle.

The three of them separated and tipped forward in the Air. Mur peered down, trying to follow the direction of Philas's gesture. He saw the orderly array of vortex lines, the dull purple bruise of the Quantum Sea beyond the crystalline Air. There seemed nothing unusual, except...

There. A small, dark knot in the Air, a hint of motion.

He turned to Dia. "Your eyes are sharper than mine. What is it?"

"People," she said, squinting down. "A group of them. Twenty or thirty, maybe. It looks like an encampment. But there's something at the center..."

"What?"

Philas thrust her face forward at Dia. "Do you you see it?" see it?"

"I think so," Dia said slowly. Her eyes narrowed. "But it might not mean anything. Philas..."

Mur was baffled. "What is it? What do you see?"

Uncertainty and fear creased Dia's small, pretty face. "It's a tetrahedron," she said.

The fifteen Human Beings gathered on the lower edge of the forest and debated what to do. Dia, fearful, uncertain, thought they shouldn't waste time on this chance encounter; she wanted simply to continue with the slog to the Pole. Mur sympathized. The Human Beings were already divided, listless, growing steadily more apathetic. It was becoming ever harder to maintain the momentum of this trek across the Mantle; and once that momentum was gone, it might be impossible to regain.

They would be stranded, wherever they stopped. And that, of course, would be unbearable for those with children at the Pole.

Philas and others argued strongly for doing something. "Think about it," she said vehemently, her thin arms raised over her head as she spoke, her fingers spread wide. "What if that really is a wormhole Interface, left over from the past? What if it's still working?"

"That's impossible," Dia said. "The Interfaces were taken down into the Core, by the Colonists after the Core Wars."

"The Mantle is a big place," someone said. "Maybe some of the Interfaces were left functioning. Maybe..."

"Yes," Philas said eagerly, "just think of that. We know that in the days before the Wars Human Beings could cross the Mantle in huge bounds, using the wormholes. If that is a working Interface down there we might complete this impossible journey in a heartbeat!"

Mur looked around at faces rendered sharp by hunger and exhaustion. Philas was weaving a dream of abandoning this ghastly journey, to reach their goal in moments with the aid of magical ancient technology. It was seductive, compelling, all but irresistible.

Despite his loyalty to Dia, he felt himself falling under the spell of that dream.

"There are already people there," he said slowly. "Around the Interface. If it is an Interface. Who's to say how they will react to us? Will they simply let us walk up and wander through?"

"Maybe they're Colonists," Philas said.

"Anyway," said someone, "we won't know unless we go to find out..."

There was a murmur of agreement. Dia dropped her head.

Philas and Mur were named as scouts, to go ahead to the artifact and investigate, leaving the rest of the Human Beings in the forest until their return.

Mur tried to comfort Dia. "It won't take us long. And perhaps..."

"Perhaps what?" She stared at him bitterly. "Perhaps there are wizards there who can restore little Jai to us. Is that what you expect?"

"Dia..."

She seemed to slump, as if the Air was collapsing out of her. "We're going to spend the rest of our lives here. Right here. Dying off one by one. Aren't we, Mur?"

Philas and Mur dived away from the forest and into the Mantle. The tetrahedral artifact might be as much as a half-day away, so they each carried a bag containing a little of the tribe's precious, and dwindling, supply of pig-meat.