Incandescence

When the first creature had finished cleaning the wall, the other one punched a hole in the bladder with the tip of one claw, and began squeezing the fluid on to the wall in a slow, painstaking fashion. As Rakesh manoeuvred himself into a better vantage point, he saw that a complex pattern of intersecting lines was already present, marked on the wall with a thinner, paler version of the bladder's dark contents. Line by line, this Arkdweller was repainting a faded sign.

Parantham caught up with him, then hovered beside him, watching in silence. When the signwriters had finished the two travelers remained, gazing at the strange symbols.

16

Zak called out, "Just a few more spans, and I'm there!"

He sounded exhausted, but utterly determined to complete the arduous climb. Roi circled anxiously around the edge of the crack. When she'd helped him up to the entrance, he'd struggled to maintain his hold on the steep, jagged surface, and she had doubted that he would make it all the way through the outer wall. She had underestimated his reserves of strength. He hadn't taxed himself needlessly on the journey; he hadn't even forced himself to stay awake to make polite conversation with his bearers when he'd felt like resting instead. He had been saving everything for this moment, and now it seemed that his strategy was about to prove its worth.

The light machine stopped chugging but it was out of reach, so Roi left the darkness undisturbed. On Zak's instructions she and Ruz were clinging to the ceiling, the idea being that if whatever had killed those who'd ventured out before was present in the void as well as the Incandescence, they would be less exposed to it here than anywhere on the floor nearby. In fact, as Roi had helped Zak into the entrance, she had seen by the glow of the light machine that the crack was twisted in a way that allowed no direct line of sight. Still, during the shomal dark phase some light from the Incandescence had nonetheless made its way right down to the floor, so she couldn't fault Zak's logic.

Zak exclaimed suddenly, "I'm outside!" A moment later he added, "There's an arc of light. I don't understand this."

"An arc?" What did he mean? "Zak?"

There was a long silence, then he replied in a labored voice, "I need to take some measurements. I'll explain everything when I get back down."

"All right." Roi was desperate to hear exactly what he'd witnessed, but she knew it was unfair to expect a running commentary. Zak didn't have much time, and he needed to concentrate on setting up the instruments and collecting the crucial data.

Whatever else there might be to discover in the void, the one possibility in which they had invested the most hope — and planning — was that Zak would be able to locate a distant object that he could track for a while, in order to obtain an independent measurement of the Splinter's motion. From inside the Splinter, there were really only two distinct numbers that could be measured: the ratio of the garm-sard and shomal-junub weights, and the ratio between the periods of the shomal-junub cycle and the turning of the plane of the Rotator's spinning bar. Those numbers were in agreement with Zak's principle, but beyond that they revealed nothing about the geometry through which the Splinter was moving. If the simple geometry that the team had found in their calculations was the right one, then the time it took the Splinter to orbit the Hub would be identical to the period of the shomal-junub cycle. If all orbits at a given distance from the Hub were the same, regardless of their angle of inclination — the assumption of symmetry on which the simple geometry was based — then a stone moving shomal and junub of the Null Line would take the same time to complete its orbit as the Splinter itself, and so it would return to its greatest distance shomal of the Null Line after exactly one orbit for both.

How could you mark a fixed point on an orbit, though, in order to measure the time it took to return to it? The idea that two orbits at an angle to each other always intersected at the same two points was the very assumption they were trying to test, so it could not provide the signposts. The only method anyone on the team had been able to come up with was to rely on a different assumption — that objects far from the Hub moved on slower orbits — and then to hope that, with the Incandescence out of the way, it would be possible to observe something in the void so distant that it was as good as fixed. The apparent motion of that distant beacon would then be due — in the most part — to the Splinter's motion around the Hub.

While Roi had paced, Ruz had been still, but now she heard him shifting, consulting his clock. "Zak?" he called. "It's halfway through the dark phase!"

A few heartbeats passed, then the reply came back, "I know."

Roi said, "We should have tied a rope around him. Then if he cut it too fine we could have just dragged him down."