The fourth pair would not agree.
Mara saw it first on the plate, in the columns. The third branch and the fourth branch, side by side round the trunk, joined by an open seam between them. Both modules had passed their own tests. Both had been shaped and folded and lined and tested alone, and each had come out within its range. Their witness marks were on their flanges. Their test records were in the forge record, read aloud before each test, as the schedule required.
But the seam between them read differently at each end.
Mara’s gauge at the seam’s top: one figure. At its bottom: another, a leaf thinner. Eshel’s rack: the same two figures. The seam was not parallel. One face was further from the other at the top than at the bottom, by a hair.
“Did someone bolt it crooked?” Sen said.
“No,” Tavin said. He was looking at the flanges with the lamp. “The bolts are square. The faces aren’t.”
Anwen was on the Lorn link with the thermal probe’s trace.
She had asked for a probe on every seam before the heat came. Eshel had clamped them on as each pair was joined: small thermocouples, one on each face of each seam, feeding the rack. The heat would come when the heart went down and the well’s flow began to move through it. When it came, each face would swell. If both faces swelled the same, the seam’s gap would stay the same.
