The name had been there while four generations of keepers called the room the old drain house.
Idri found it on the morning of day 1234, under a plate that somebody had turned against the wall to keep rain out of a broken gauge window. She had taken the cover down to make a measured replacement. On its hidden face, shallow letters ran beside a row of drilled registration marks.
ROOTWELL WESTERN RETURN. LOCAL STOPS RETAINED AT EACH EXCHANGE.
The second line mattered to Lessa as much as the first.
“Copy all of it,” she told Elian. “Not just the part that makes a good heading.”
The old drain house stood at the top of the cooling yard. Its accessible lower room had held spare pipe and a bed of sand used to weight the maintenance platforms. The upper wall contained a stopped instrument connected to the old return gallery by a narrow sampling line. It had not controlled the heating system. No hidden handle inside it had been secretly commanding every town they had visited.
Fen compared the plate with the oldest industrial sheet. The sheet showed a western return, an exchange and a line continuing beyond the quarry. Its edge was torn where a second sheet should have attached. They knew that sort of absence now. It was a reason to look for the next page, not a right to draw whatever would make the first one simple.
