The crew chief took the third panel off too, and the fourth, and behind them the recesses went on.
A ring of them. Mara could see it now, with Sen’s lamp held into the passage from its mouth and the crew chief’s cap lamp moving along the wall ten meters in: a row of recesses set into the lattice’s outer skin at regular intervals, curving away along the passage with the curve of the cage. Each one the size of a forearm. Each one cut to a precise curve at its edge. Each one with a groove at its base, deeper, stepped, as if cut to take something with a shaped foot.
“Service sockets,” Sen said.
She said it slowly, as if naming something she had heard of and never seen.
“On the guild’s oldest plans,” she said. “Before the pump hall. There’s a note. Service sockets, cold side, for replaceable ribs.” She looked at the recesses. “Nobody’s seen them. Nobody knew where they were. The plan didn’t say.”
“Ribs,” Mara said.
“The lattice’s ribs,” Sen said. “The struts. The ones that bow.” She looked at the screen across the chamber, where the bow showed. “The Founders built the cage so its ribs could be replaced. From here. From the cold side. Slid out of their sockets and new ones slid in.”
