She found the groove because she went back for more root, and because she went slowly.
There had not been enough. Six crystals of root iron in the box, small and dense. She had done the arithmetic on the bench, crudely, with Orison’s help: how much of each grade a heart would need, in what proportion, and the answer was more root than crown and more crown than seam, and she had more seam than either. So she went back out along Sera’s rail to the base of the fan, where the thick heavy crystals grew close to the shell, to cut more.
She cut one. It came away humming. She reached for the next, a crystal growing a little apart from the others in a shallow hollow of the shell, and as she cleared the frost from around its base with the file’s flat, she saw the line.
It was under the deposit. Beneath the frost, in the shell’s dark surface. A groove.
She stopped. She brushed away more of the frost, gently, with the side of her glove. The groove ran across the hollow, straight, a hand’s length long and perhaps a finger’s width wide. Its edges were sharp. Clean. They caught the light from the drum and shone, silver against the shell’s dark grey, the way fresh cuts in old metal always shone.
