Incandescence

14

“Thirty-three,” Roi counted, vigorously waving her back left leg, followed by her front left leg.

“THIRTY-THREE!” the hatchlings replied in unison, mimicking her actions precisely.

“Thirty-four.” Roi waved her back left leg, then her middle left.

“THIRTY-FOUR!” echoed the hatchlings.

“Thirty-five.” Back left leg once, then once again.

“THIRTY-FIVE!”

“Thirty-six.” Roi leaped off the floor as high as she could, struggling to wave her front right leg twice, clearly and distinctly, before she touched the ground again.

“THIRTY-SIX!” The hatchlings couldn’t jump as high as she had, but they were all nimble and energetic enough to repeat her gestures before they had even begun to descend.

Roi rolled over on to her back, exhausted. The hatchlings, of course, copied even this unintended flourish. They really were infuriating sometimes.

“I’m getting too old for this,” she rasped to Gul.

“You just need to spend less time at the Null Line.”

“Maybe.”

While she rested, Gul took over the class, pouring a fine colored powder on to the floor and scraping furrows in the shape of simple words. As Roi watched the hatchlings copy him, her tiredness and irritation faded. She knew it would be a joy to teach these children, to bring them to an understanding of the world.

It was also a daunting responsibility, but she believed she had grown better at the job. She had tutored seven groups of hatchlings so far, and from the last three groups she was sure that everyone had left her class with a clear understanding of the basic facts about the Splinter. They would carry that knowledge with them throughout their lives, and spread it among their team-mates.

The great tunnel that Bard had planned, to unbalance the force of the wind and drag the Splinter to safety, remained unbuilt. While Bard, Neth and a few dozen others continued to survey, and recruit, and try their best to explain the tunnel’s purpose to the people of the sardside whose factories, storerooms and grazing areas they wanted to turn to rubble, so far they had failed to recruit a workforce large enough to make a scratch in the rock, and the locals remained largely hostile to the whole idea. Roi couldn’t see the situation changing while the threat of the Splinter descending into an unstable orbit around the Hub remained an incomprehensible notion to most people. She suspected that it would take at least two generations for Zak’s vision to permeate the culture to the point where everyone could understand the danger, but at least she and Gul, and a dozen other teams, were nudging things in the right direction. Move the people, and the rock might follow.

The hatchlings completed tracing the words for “left” and “right” and began smoothing the powder into its blank state again, ready for the next word. Suddenly the weight changed, and Roi, Gul, hatchlings and powder were flung high into the chamber. An instant later, the Incandescence brightened, sixfold, thirty-six-fold, searing everything into invisibility.

Roi thought: This is the end. So soon. No warning, just death—

She struck the floor, right way up. After a moment she flexed her legs cautiously; she was sore from the impact, but she had not been injured. She heard the hatchlings mewling in distress beside her; still blinded, she instinctively chirped out words of comfort and reassurance. “Everything is fine! We’re safe! Don’t worry!”

As her vision began to return, she could see that the walls around her still bore an afterglow from the burst of light, a lingering radiance far stronger than anything she’d witnessed before, even at the garm-sharq edge. She could feel the rock creaking ominously beneath her. Was the Splinter about to be broken in two? Or was it on the verge of plummeting into the Hub? This was not how she’d imagined either disaster beginning. As far as she could judge, once the disturbance that had tossed them from the floor had passed the weight had returned to normal.

Gul limped over to her. “Any idea what’s happening?”

“None at all.”

“Do you think we should head sardwards?” That was one plan that had been mooted as a response to an impending division: head for the sardside, in the hope that the sardwards fragment of the Splinter would end up further from the Hub.

“We’re a long way from the Calm,” Roi pointed out, “and the hatchlings can’t move as quickly as adults. It would take us two shifts, at least. If we’re breaking up, we might be heading into danger.” If the Splinter divided symmetrically, the Calm was the last place you’d want to be when the halves violently parted company.

“That’s true,” Gul said. “And if we’re going to get thrown around again, travel is probably unwise unless we’re sure our lives depend on it. Let’s wait and see if we can make sense of the situation.” The hatchlings were milling around them making plaintive sounds, but their small bodies were resilient and none of them appeared to have been harmed by the fall. Gul chirped soothing words to them at his most reassuring pitch.

The walls around them were growing darker now. At first, Roi had thought it was just the afterglow from the flash continuing to fade, but as she increased the sensitivity of her vision to compensate, she realized that she was straining at the edge of her ability.

“Am I going blind?” she asked Gul. “Or is the Incandescence fading?” Maybe the flash had damaged her sight.

He said, “Either we’re both going blind, or it’s fading.”

The hatchlings fell silent, as if the darkness itself was a source of tranquility for them. Perhaps it was lulling them to sleep, just as the voluntary cessation of vision induced drowsiness. Roi could think of no other experience with which to compare it; the Incandescence might penetrate the rock more weakly in the depths of the Splinter than it did at the edge, but for the all-pervading glow to change before her eyes was unprecedented.

As the darkness grew deeper, Roi tried to stay calm. Whatever was happening to the Splinter was not a fate that anyone had predicted, but it was better to be perplexed and alive than to face those long-anticipated cataclysms.

“Can there be a hole in the Incandescence?” Gul wondered. “A gap, a void?”

“If there is, why did we never pass through it before?”

“Perhaps it moves, perhaps it wanders around,” he suggested. “And that flash of brightness was. a concentration of the Incandescence at the edge of the void, heaped up like the rubble dug from a hole.”

Roi had no idea if that made sense; she had never thought of the Incandescence as something you could make a hole in by any method. “Can you feel the wind?” It was a measure of how disoriented she was that she had to ask, that she couldn’t trust her own senses.

“No. There’s nothing. The rock is making a sound I’ve never heard before, but it’s not from the wind.”

Roi was relieved by this small sign of consistency. “I suppose that means we’re not simply going blind. Wind and brightness, gone together.” With the Incandescence gone, how would they eat? How would they survive? If the hole they had entered was not too large they should emerge from it soon, as the Splinter continued its orbit around the Hub. If it enclosed their whole orbit, though, they would remain in darkness until it moved away of its own accord.

Roi said, “How long do you think it’s been, since the darkness started?”

Gul rasped amusement. “My mind’s not that clear. I wouldn’t like to guess.”

“Less than half a shomal-junub cycle, I’d say.” Roi had watched the cycling stones so many times, the rhythm of it was stamped into her mind. “We don’t know for sure that the Splinter’s orbit has the same period, but that’s what the simplest geometry implied. So if there’s a gap in the Incandescence that’s smaller than our orbit, we ought to emerge from it in less than one shomal-junub cycle.”

“That sounds reasonable,” Gul said cautiously. “The gap itself might be moving around, complicating things, but if it’s moving slowly then everything should repeat about once every orbit.”

Just a few heartbeats later, the walls began to brighten. Roi tensed, preparing herself for a recurrence of the violence that had preceded the onset of darkness, but the light from the rock climbed calmly and steadily back to its normal strength, and the wind resumed its usual susurration, unaccompanied by any sudden shifts of weight or blinding flashes.

The strange creaking and rasping from the rock did not abate, though.

“Half a shomal-junub cycle,” Roi said. “Almost exactly half.”

Some of the hatchlings began to stir. Gul made soothing noises and drew them close to his body. “Why would a void in the Incandescence be half the size of our orbit?” he said. “That seems like too much of a coincidence.”

Roi took advantage of the normal light to survey the chamber. All the hatchlings were accounted for, and the basic structures around her were intact—the entrances to the chamber were clear, the ceiling hadn’t fallen—but there were some cracks in the walls that she was sure she’d never seen before. The rock continued its maddening groan. If she could feel no change in weight, what was tormenting it?

She could hear people in the distance, calling to each other, fearful and confused. “Where should we go for safety?” she asked.

Gul said, “We’re as safe here as anywhere. There’s nowhere to go.”

The light and the wind began to fade again. Why were some things repeating themselves, while the flash and the jolt had happened only once?

Roi said, “We were pushed.” The pattern was unmistakable; she’d tossed enough stones in the Null Chamber to know how to set things cycling back and forth. “That’s what threw us off the ground. It wasn’t the fact that we entered the void that did it: the push came first, the disturbance came first. Whatever struck us changed our orbit slightly, enough to knock us into the void.”

“Why is the void half as big as our orbit, though?” Gul protested.

The darkness thickened, the wind fell away. Roi pictured the orbit of the Splinter, and the motion of the stones in the Null Chamber. What happened twice in every shomal-junub cycle? The “falling” stone passed by the “fixed” one. First it passed it on its way shomal, then it did so again on its way junub. Twice in each cycle, the stones were close together. And twice, they were far apart.

“The void’s not half as big as our orbit,” she said. “It’s far bigger than that. And it hasn’t wandered up to us by chance; it hasn’t moved at all. It’s been right beside us all along.”

Gul was silent for a while, contemplating her cryptic remarks. Then he said, “If the Incandescence isn’t everywhere, but we never left it before, then maybe it’s confined to a thin layer around the plane of our old orbit. Now something’s disturbed the Splinter, and we’re moving shomal and junub—above and below that plane—for the first time.”

“Exactly!” Roi said. “Out of the Incandescence, then back. Twice every shomal-junub cycle. The whole Splinter has become the falling stone.”

She waited, picturing the stones in her mind’s eye. As one imaginary stone ascended from its low point and approached the other, the walls began to brighten.

Gul said soberly, “We’re lucky we survived this. And lucky we can understand it.” Then he let out an ecstatic chirp that woke half the hatchlings. “We’re not going to die!” He scooped up two bewildered children and tossed them on to his back, then started running around in a circle. “Darkness, light, it doesn’t matter! We’re safe, we’re fine. Everything is perfect!”

Roi watched him, dizzy with relief herself, if not so exuberant. This was not the end of the Splinter, not the plunge into the Hub that Neth had foretold. The crops would suffer, though. There would be food shortages, and everyone would struggle to complete their work as the darkness came and went.

The strange event had shown them something new about the Incandescence, even as it had confirmed Zak’s picture of the Splinter orbiting the Hub. It might even persuade some people to accept his ideas and agree to the tunnel. The loss of crops was a hard price to pay, but in the end it might change things for the better.

The one thing that worried Roi most was that she still had no idea what dazzling thing had flown past and knocked them out of their orbit. Where had it gone? To the Hub? Into the void? Could it cross their path again?

And if it did return, which way would it push them next?

Zak stretched his legs out across the wall of his chamber, trying to ease the pain in the joints. “I have a plan,” he said. “But I’m going to need your help.”

“Whatever you want from me, just ask.” Roi had left the hatchlings in Gul’s care to travel to the Null Line and check on Zak’s condition. He had survived the Splinter’s Jolt and the aftermath, with members of the theorists’ team still bringing him food regularly, in spite of their own problems and distractions. His health had been fading for a long time before the event, though, and Roi suspected that his death was close now.

Zak said, “When I was working in the library, I heard about a crack in the wall at the junub edge. Some people had climbed right through it and reached the Incandescence.”

Roi was skeptical. “Are you sure that’s not just a story?”

“I have a map.”

“You always have a map. Did anyone come back?”

“Of course not. The Incandescence killed them; nobody has ever walked into it and survived. It’s not just the strength of the unfiltered wind: even at the Calm, there’s something fatal, something that the rock protects us from.”

Roi could see where this was heading. “You think it might be possible to survive there, now? In the times when our orbit takes us right out of the Incandescence?”

“It’s worth trying,” Zak said. “We don’t know how long the new orbit will last. This might be our only chance to look into the void.”

There had already been measurable changes in the orbit. Although the period of the complete light/dark cycle remained the same, with Ruz’s clock it had been possible to detect a small reduction in the time the Splinter spent in darkness. This suggested that the total distance they were traveling away from the old orbital plane had diminished slightly.

Other experiments in the Null Chamber had shown that the Null Line had, strictly speaking, vanished; although the weight throughout the chamber remained very small, there was no longer a line of perfect weightlessness running through the Splinter. The small weights that were present now were difficult to measure, but they seemed to undergo cyclic changes. Tan had suggested two possible explanations for this: either the Splinter’s rate and axis of spin had been disturbed in such a way that the spin weight no longer canceled the rarb-sharq weight, or the rarb-sharq weight itself was no longer constant throughout each orbit, and hence could no longer be canceled by any constant spin.

In either case, the ceaseless groaning of the rock was probably due to the fact that the weights throughout the Splinter were no longer fixed; the precise forces were always shifting, repeatedly tightening and relaxing their grip on the rock. Tan believed that the price to be paid for this restlessness would be a gradual return to a state of alignment, whether that meant a change in the Splinter’s spin, its orbit, or both.

Roi said, “This journey will be hard for you. Someone younger and healthier should go instead.”

“Someone younger and healthier might climb out through the crack in the wall and never come back. It makes far more sense for me to risk the last few shifts of my own life than to allow someone else to throw away the best part of theirs.”

“You can barely walk,” Roi protested. “How are you going to reach the junub edge?”

“I’ve arranged for some couriers to bring me a cart.”

“Are they going to deliver you to your destination as well?”

Zak said, “I want you to pull the cart. You and Ruz. Ruz has already made some instruments for me, to allow me to take measurements of whatever’s there to see.”

“So you want Ruz along to fix them if they break?”

“Yes.”

Roi didn’t ask what her own purpose would be, apart from sharing the load. She said, “You should have peace and ease at the end of your life, not a dangerous journey like this.”

Zak rasped irritably. “If I knew that the Splinter was safe, I’d have peace. But I’m sure that it’s not, so the best I can do is keep struggling to make that happen.”

Roi made a sound of acquiescence. “What do you think it will tell us? Looking into the void?” The thing that had lit up the rock when it touched them seemed to have vanished, but then, from inside the Splinter the whole Incandescence seemed to vanish when they were no longer immersed in it.

Zak said, “We’ve been half right about a lot of things, but there’s something missing from our theories, something whose nature we haven’t even guessed yet. If we don’t learn to understand it, it will kill us.”

When Roi returned to the hatchlings’ chamber to explain her plans, she found Gul in pain, full of ripe seed packets. She had helped him dispose of them many times before, but she was surprised that he hadn’t found someone else while she was gone.

“I’ve been busy with the hatchlings,” he said. “What was I supposed to do? Walk the tunnels begging for a mate, with the children lined up behind me copying every move?”

The hatchlings were asleep, so there was no danger of that now, but Roi had no contraceptive leaves. She was too tired to go hunting for the stupid weed, but she couldn’t bear to see Gul in so much pain.

“Open your carapace,” she said. “I’ll take them.”

“Are you sure?”

“Quickly, before it gets dark. If I can’t see what I’m doing you’ll be sorry.”

As she snipped the seed packets free and loaded them into her egg cavities, the pleasure that spread through her body felt muted. Without the contraceptive to compete with them, the packets were producing far weaker secretions than she was accustomed to. She had never been entirely sure why it had always seemed right to keep her eggs from being fertilized; she had understood that the Splinter could only feed so many mouths, but other people made hatchlings all the time. Now, with the crops diminished, that should have been a stronger reason than ever, but even as the rush of contentment faded she felt no regret for what she’d done.

She had planned to stay for less than a shift before returning to the Calm to meet up with Zak and Ruz, but she found herself lingering, waiting for her eggs to be ready to lay. Six had been fertilized, and when their cases finally hardened she found a snug crevice close to the chamber where Gul worked, and she packed the eggs carefully into the gap in the rock.

She was aware of how strange it was that she was arranging for these hatchlings to be educated by their father, rather than leaving it to chance. The job itself was the thing, and every member of every work team, not to mention every hatchling, was supposed to be interchangeable. Still, in these dangerous times everyone’s children needed to learn what Gul could teach them. She would have counselled any stranger to do the same.

Although Roi was late returning to the Calm, when she arrived she found that the cart Zak had hoped to receive several shifts before had only just been delivered. That the metalworkers, couriers and depot operators had managed to fulfill Zak’s strange request at all—while the food around them became ever more sparse, and the world of constant brightness they had known all their lives flickered in and out of existence—was testimony to the robustness of the work teams. Some people, Roi suspected, would not miss a shift even if the Splinter itself was torn apart.

The cart was big enough to hold Zak, the instruments Ruz had built for him, and a reasonable amount of provisions. Roi had already collected some food on her way back from visiting Gul, but she spent another shift foraging until she had as much as they could carry. Although the Calm supposedly became less barren as you moved away from the Null Line, and so in theory they’d be traveling into a more bountiful region, Roi had spent so long around the Null Chamber that she knew a dozen places where the seeds that drifted in tended to settle and grow. She would not have the same local knowledge once the journey was under way.

There were two harnesses for the cart, strung together one behind the other, so she and Ruz could share the load if they wished, but the cart would not be unbalanced if they chose to take turns pulling it instead.

The whole team of theorists came to bid them farewell; Tan addressed Zak on behalf of everyone. “We wish you a safe journey, and clear observations,” he declared. “Our frames are ready for your numbers and templates. You built this team from nothing; perhaps you will return to us with the knowledge that will make our work complete.” Zak replied simply with a murmur of thanks, but the send-off seemed to lift his spirits.

Roi took the harness first, leaving Ruz free to walk ahead of her, checking for hazards and clearing obstacles. The Jolt had left debris almost everywhere, and the less-traveled the tunnel the more chance there was that nobody had yet moved it aside.

Their journey would take them rarb and junub, uphill all the way, but it would be a while before their weight made much difference. Even in near weightlessness the cart was unwieldy, but by far the greatest irritation was the darkness. In her earlier trips between the hatchlings and the Null Chamber, traveling alone with no burden, Roi had found it impossible to make progress once the light fell away and her vision failed. The path ahead could be clear for dozens of spans and she could declare to herself that nothing terrible would befall her if she simply advanced at a leisurely pace through the darkness, but her body would still refuse to obey her after the first few halting steps. Attempting the same thing with Zak swaying on the cart behind her was inconceivable, even if Ruz had been in the harness to remove him as an unknown. The periods of enforced rest might have been welcome if not for the fact that they came so much more frequently than they were needed, making them more frustrating than recuperative.

“What is light?” Roi wondered, waiting for the darkness to end.

“A very fine part of the wind, perhaps,” Zak suggested. “That would explain why it can penetrate more deeply through the rock than any other component. It seems it can penetrate anything but metal.”

“It must be easily scattered, though,” Ruz said, “or there’d be no light at all here in the Calm. The rock can’t block it completely, but still manages to change its direction.”

“Yes.” Zak seemed intrigued by this observation, but unsure how to pursue it further.

Roi said, “If light is part of the wind, how can we hope to see anything at all once we’re out of the Incandescence?”

“Some light might be scattered up to us from the Incandescence,” Zak replied. “But the void itself might contain a faint wind.”

“Including light?”

“Let’s hope so,” Zak said. “All we know for sure about the void is that it’s a thinning of the Incandescence, to the point where nothing can reach us through the rock. That need not mean that there’s absolutely nothing there.”

The tunnel began to brighten again. It always took a while for the walls to begin glowing with their full intensity, though how much of that was due to the time it took for the light to penetrate the rock, and how much might be the product of a gradual transition between the void and the Incandescence, was hard to say. From outside the rock it might be possible to judge how sharp the border between the two regions was, though it would be risky to stay outside beyond the periods of full darkness.

It was only after they’d been traveling for nearly a shift and a half, according to Ruz’s clock, that they decided to stop and sleep. Before the Jolt, most people had more or less agreed on the length of a shift, growing tired after a similar period of wakefulness. The stretches of darkness had led to an increase in that time, but not always an equal one for each person.

When they woke, Ruz was first in the harness. After a dozen light/dark cycles Roi took his place, and this time she finally felt the burden of pulling the cart uphill. The junub weight grew less than half as rapidly with distance as the garm and sard weights—and they were also traveling rarb, which contributed nothing—but beyond those excuses it was a measure of how slow their progress had been that it had taken so long to reach the point where they really cared which way was up.

The Calm appeared more sparsely populated than ever; apart from occasional couriers that Roi glimpsed in the distance, their role made obvious by carts of their own, the tunnels seemed deserted. The expeditioners passed the time with light-hearted speculation, eschewing any grim predictions about the fate of the Splinter. By the end of the journey’s second shift, Roi and Ruz were dragging the cart together, with the lead harnessee also keeping a lookout for obstacles. It was hard work now, and Roi was beginning to feel that their enforced breaks didn’t come a moment too soon.

Halfway through the third shift, as they slowed for the onset of darkness, Roi noticed a flicker of light ahead. At first she thought it was merely a lode in the rock that was dimming more slowly than its surroundings, but as the darkness deepened the contrast only grew stronger. A reddish patch of light stood out against the blackness; it was an unsteady glow, but it never failed entirely. It was moving slightly, with a rhythm that reminded her of a person’s gait, as if someone was carrying the source of the light toward them.

Ruz said, “Can you hear footsteps?”

Roi listened carefully. “Yes.”

“There are five people,” Ruz declared. “And some kind of machine.”

“I’ll take your word for it.” A dozen heartbeats later, she could make out two people in the front of a small group. The light was coming from an object strapped to one of their backs.

Zak said quietly, “That I lived to see such wonders.”

Roi called out a greeting, unsure if the three of them would be visible by this strange illumination. A reply came back, cautious but friendly.

When the group drew closer, Roi could see that Ruz was correct: there were five people. They made introductions; the light-bearer was called Lud, and the others were Jos, Rud, Cot and Sad.

The light that emerged from the machine on Lud’s back was weak, rendering the group sketchily. Their bodies were merely hinted at by a glimmer of surfaces, as if their carapaces had turned to metal. Seeing your companions’ beating hearts was not the point, though; this modest light would still be enough to allow you to spot obstacles and walk through the darkness with confidence.

“Where are you headed?” Ruz asked politely. Roi was sure that he was twice as eager as she was to hear how the light machine worked, but it would be discourteous to raise the matter immediately.

“We have no destination yet,” Jos replied. “We want to know what’s happening to the Splinter, so we’ve left our teams to search for answers.”

Roi could hardly believe what she was hearing. They’d left their teams? How? Had the Jolt shaken them free, like the rubble it had torn from the solid walls?

She said, “We have some ideas about what’s happening to the Splinter. We believe something has pushed it, and now it’s falling back and forth, in and out of the Incandescence.”

Lud said, “Falling back and forth?”

“If you throw something shomal from the Null Line,” Ruz explained, “it will reach a certain distance, fall back to the Null Line, go past it some way junub, fall back again, and so on. We think the Incandescence ends if you go far enough shomal or junub, and that’s why the light comes and goes.”

The group talked this over among themselves, then asked to hear more. Zak remained quiet, which usually meant that he was tired or in pain, so Roi explained his idea of the Splinter orbiting the Hub, and the experiments in the Null Chamber that seemed to support it.

While they were talking the light from the machine faded, and its whirring sound died away. But the walls were already beginning to brighten, and soon Roi had a normal view of everyone. They had a small cart with them, full of metal parts.

Cot climbed on to Lud’s back and began turning a handle attached to the machine. Ruz could no longer contain himself. “It’s spring driven, isn’t it?”

“Of course,” Lud said. “Trying to crank it smoothly and walking at the same time would be impossible.”

“But what makes the light?” Ruz’s tone was drenched with such longing that he might have been a starving child begging for food.

Lud chirped with amusement. “Just two rough surfaces scraped over each other, under pressure. Rough enough to make a disturbance, but not so rough that they’ll stick.”

Jos added, “I found the effect completely by luck. I was grinding plants into a powder between two stones, and I grew tired of stopping work every time it grew dark. When I ground stone against stone with nothing between them, a faint light seemed to come from the point of contact. At first I thought I was just going mad from the darkness, but the more effort I applied, and the less of the mush there was to smooth the stones, the stronger the light became.”

Roi said, “So you’ve left your old teams now? You’ve formed a new one, and you’re looking for recruits?”

“Not exactly,” Cot replied, working briskly to ensure that the spring was fully wound before the darkness returned. “We still don’t know what’s the best thing to do. We’ll form a team if that’s necessary, but we’re willing to join an existing one if they can make a good case that they know what’s going on and that they’re doing something useful about it.”

Every time Roi thought she could no longer be shocked, these people outdid themselves. It had taken a great struggle for her to tear herself free of her work team to join Zak. On that first journey to the Null Chamber she had never been able to admit her intentions, even to herself. Now here were five people roaming the Splinter, challenging every passing stranger to make a reasoned bid for their labor, as if the whole idea of recruitment had been turned inside out.

Zak spoke softly. “Some people are trying to build a tunnel that will change the way the wind pushes on the Splinter. If they succeed, they hope it will carry us to safety. I’m sure they could use your skills.”

Lud said, “I can make no promises, but we’d be happy to talk to them, to hear their case.”

Ruz said, “We can draw you a map, give you directions.”

“You’re not going there yourself?” asked Sad.

“We have another task.” Roi explained about the crack in the wall, and the observations that they hoped would clarify both the Splinter’s ordinary motion and the nature of the Jolt.

The idea struck a chord with the light-makers, and they seemed torn between joining Zak’s expedition and heading for the sardside and the tunnel-makers. Zak, however, explained that he would be making the observations alone and that his two assistants were all that he needed.

Cot said, “Then at least take this with you to help you on your way.” He opened the cart and produced a second light machine. “We brought two spares, and plenty of parts. If you take this one, we will still have no trouble reaching the sardside.”

Zak said, “Thank you.” Roi would have preferred an extra body or two to help pull Zak’s cart; this was more weight to carry, and now they’d have no excuse to rest when darkness came. Still, at least this way they could choose their own pace.

Roi drew a map for the light-makers showing the way to Bard’s team, and the two groups parted. Ruz agreed to carry the light machine on his back; he took the rear harness so as not to obstruct Roi’s view ahead.

They toiled on toward the junub edge, resting as they wished and using the machine to enable them to travel through the darkness. At first Roi found the strange, shallow illumination it cast disorienting, but after a dozen cycles she was accustomed to it, her mind switching easily between the two ways of seeing.

It was hard work winding the spring, though. “I want you to improve on the design,” she told Ruz.

“In what way?”

“I want a version that works unattended, filling itself with light when there’s light to spare, then releasing it in the darkness.”

As they approached the edge the tunnels became increasingly strewn with rubble and the walls ever more fractured. Some of this might have been due to the Jolt, but Roi had heard descriptions of the area that long predated that event. It was easy to believe in a crack in the outer wall here, if not so easy to reach it.

Ruz, who had been timing the lengths of each stretch of light and darkness, reported that he’d finally started to detect a small asymmetry between successive times spent in the dark. Now that they were a significant distance away from the Null Line, when the Splinter moved junub of the Incandescence the darkness came earlier, and lasted longer, than when it moved shomal. Roi had already noticed a difference in the way the light penetrated the rocks, with the onset of brightness coming faster when it started from above than from below, but every sign that confirmed their guesses about the Splinter’s motion through the Incandescence was important. Apart from anything else, they would be relying on the rock of the Splinter to protect Zak from any dangerous emanations; they did not want to misidentify the phases of the cycle and send him out in the wrong period of darkness, to find the Incandescence looming directly above him.

Shifting enough rubble to allow them to steer the cart through the tunnel became an impossible task. Roi helped Zak pack the instruments into his cavities, then had him climb on to her back. According to Zak’s map they did not have far to go, but the map contained no annotations about the ease of travel along the tunnels it portrayed—let alone an up-to-date account that included the damage wrought by the Jolt.

Roi noticed a slight thickening in the sparse vegetation on the walls before she felt the faint hint of a wind, rising and dying with the light. This close to the Calm, that could only mean that the feeble wind had almost no rock to penetrate. She moved ahead cautiously, afraid that they might all be caught by surprise with no roof above them, but as they approached the intersection marked on the map as lying directly beneath the crack, the onset of light brought no blinding revelation. If anything, this place seemed less bright than the garm-sharq edge.

Still, the vegetation on the roof was the thickest Roi had seen since they’d set out from the Null Chamber. She set Zak down and clambered up the wall to explore it. She hadn’t walked upside down in weight like this for a long time, and the encrusted surface didn’t make it any easier.

She probed the surface gently with her claws. “The rock feels strong,” she reported. “No gaps, no cracks.”

Ruz said, “Maybe the vegetation’s repaired it.”

“All my maps are too old,” Zak lamented. “We should have brought tools to cut our way out.”

“Tools, and a very large work team,” Roi suggested. She’d heard it said that the outer wall was at least a dozen spans thick, though like much common knowledge that claim might not have had much grounding in solid information.

Ruz said, “If there’s a system of cracks, there might be other openings. Even if the vegetation got to all the old ones, the Jolt might have broken a way through somewhere else.”

Roi climbed down to the floor. “Stay here with Zak,” she said. “I’ll take a look around.”

She continued along the tunnel by which they’d reached the intersection. When the darkness came she froze and looked back, but there was no faint glow in the distance; she hadn’t bothered to rewind the light machine, and apparently Ruz hadn’t either.

As the light returned she advanced slowly, listening to the wind. The sound had an odd, resonant beat that she’d never heard before, and as she approached the next intersection it grew louder.

She turned right into the cross-tunnel, pursuing the sound. The floor of the tunnel was piled high with rubble, and it reached the point where it became easier just to climb on to the ceiling and stay there. When darkness fell once more it hardly seemed to matter; there might be cracks here, but at least she couldn’t slip on a loose stone. She inched her way forward through the blackness.

When the wind rose up again, Roi could hardly believe that she was in the Calm. Even at the garm-sharq edge she’d felt nothing like this; her carapace tingled beneath the assault as if she was being pelted with fine sand.

The light now was brighter than she’d ever seen it. Brighter everywhere, but ahead, opposite the mouth of a side tunnel, a patch on the wall was almost blinding.

She dimmed her vision as much as she could, and approached the intersection cautiously. As she turned to peer into the side tunnel she saw the floor ahead awash with radiance, blazing too brightly to bear. She retreated, her heart racing.

When the next cycle of darkness came and the light ebbed from the surrounding rock, the intersection did not lose its strange radiance entirely. Roi approached the entrance to the side tunnel again, and looked toward the place that had been intolerably bright before. She could see a hole in the ceiling, with a ragged patch of the floor illuminated beneath it. The Incandescence was far away now, but it seemed that a part of its light was still reaching through that hole.

No doubt remained in Roi’s mind: this was a crack in the Splinter’s edge, leading out to whatever lay beyond. The next time darkness fell the Incandescence would lie safely on the other side, and the secrets of the void would be rendered visible to whoever dared step outside.