The command well’s old furnace had plenty of heat and no fine control.
Mara opened its control panel on the morning of day twenty-one. A brass plate on the furnace’s side, held by four screws, behind which a row of setpoint dials sat in a recess, each one stamped in the Founders’ format. She read them. Temperature. Rise rate. Hold time. Fall rate.
One band. One set of dials. One standard run for the whole furnace, from its door to its back wall. Built for uniform Founder stock: a single metal, heated evenly, from end to end.
The composite was not uniform.
Crown iron at the ends. Water-main alloy in the middle. Mirror iron along the inner face. Three metals, each expanding at a different rate when heated, each cooling at a different rate. A standard run would heat the whole rib the same. The water-main middle would expand faster than the crown iron ends. And the mirror lining, laid along the inner face, would be pulled by the middle as it grew and held by the ends as they lagged.
It would pull away from the rib. Before the rib was ever installed.
Mara closed the panel.
“It can’t do zones,” she said.
