Incandescence

It seemed that a large piece of rock had sheared off the side of the Splinter. What was gone included the original mouth of the new tunnel, and all six of the first set of plug chambers. The next set, downwind from that, remained intact. Many dozens of people had certainly been killed, some of them carried off into the Incandescence inside the fragment that had broken away, others seared by exposure. The ordinary system of tunnels was now open to the Incandescence, but that in itself wouldn't cause any more harm if people kept away from the damaged region.

Roi had sent Haf to search for Neth, but he returned with no news of her. She tried to set aside her fears for her friend, and think through the other ramifications of the disaster. The tunnel was still open, and could still be controlled by the remaining plugs and baffles. If the cracks caused by the construction ran deeper, if more of the Splinter's rock was threatened, it was hard to imagine any easy solution to that now. Leaving this tunnel open, and closing down the other two instead if they needed to adjust the balance of forces, was about the only strategy Roi could think of to minimize the risk; shutting off the flow was just as likely to trigger another failure in the rock.

Haf said, "Why is the wind blowing from rarb-junub?"

"What?" Roi had become disoriented. She looked to the nearest wall sign; Haf was right. She found Neth's student, Sen, huddled against the rock and asked her if she could explain the anomaly in terms of the damage, the local density of the rock, the possibility of a redirection of the flow.

Sen had trouble concentrating; she was still in shock from their brush with death, and Neth's disappearance. She did her best to analyze the problem, but she couldn't rule anything in or out.

Roi asked Bard to send a message to the void-watchers, asking them if they'd noticed any changes in their latest observations. When the reply came back from Ruz, it was exactly as she'd feared:

"The Splinter has gained a spin around the garm-sard axis. Direction is junub to rarb. Period about seventeen times shomal-junub cycle."

The slow spin would be rotating the tunnels in and out of alignment with the wind, slashing their effect to a fraction of what it had been. If it could not be corrected, they would be left with far less speed and manoeuvrability than when the first tunnel had been opened.

Bard said, "If we have to cut more tunnels, we can do that."

"And lose more rock? More people?"

"What choice do we have?" he replied. "Can we pass the Wanderer safely in this state?"

"I don't know. I don't know how much power we will have lost, I don't know how the whole picture will have changed."

Roi sent a message to Kem, to be sure that she knew exactly what had happened, and was thinking about these problems. Then she approached Sen again.

"I need your help," Roi said gently.

Sen still couldn't get out of her flattened defensive posture; she wanted the walls to hide her, to swallow her.

"The Splinter is spinning," Roi told her. "The only way I can think of to correct that is to use the baffles in the tunnels, and try to modulate the flows to provide a torque to bring us to a halt."

Sen struggled to focus. "I think the most stable alignment for the Splinter with respect to the wind would be with the tunnels running rarb-sharq again. In time, we should settle back to that naturally."

"That sounds likely," Roi said, "but we can't rely on it happening in time. We need to get stabilized as soon as we can."

"We never planned for this," Sen replied. "Neth and I. We never did the calculations."

"But you understand her ideas? You can work it out?" Roi had only the crudest notion of Neth's work herself. Even if she found the written notes, it would take her thirty-six shifts to begin to master the theory of wind flow.

"Perhaps I can do it," said Sen. "Perhaps."

Bard found a chamber for them to work in, close to an existing light-message route, and set up a control post with Roi, Sen, Haf, and a dozen checkers.

As the great tunnels swung around, the wind would strike first one side wall, as they approached rarb, and then the other as they turned away from it. If there was any natural effect that would favor one wall in a manner that could halt the spin, Roi couldn't see it operating on the kind of time scale they needed. They would have to try to take control of the flow, using the baffles to ensure that the wind hit the rock with the maximum possible force when it could retard the spin, but passed through the tunnel as smoothly as possible at all other times. Like the imbalance between the garmside and sardside that had carried them away from the Hub, they could try to break the natural symmetry of the situation to work to their advantage.