Jon did not pull on the wheel a second time.
He held his hands completely still on the hot, rust-scaled iron rim and called over his shoulder into the trench: “Garrick, hand me your wire brush and the small tallow lamp. Nobody touch the spindle yet.”
Garrick Holt passed the stiff iron-bristle forge brush and a narrow brass miner’s lamp through the two-foot breach. Leaning his chest against the warm granite sill of the opening, Jon hooked the lamp onto the upper flange bolt of the conduit and carefully brushed the thick crust of red iron oxide, dry furnace clinker, and calcified lime scale off the six cast-iron spokes and the central hexagonal boss of the wheel.
Behind him on the timber cradle, Alden Bram adjusted his spectacles and leaned in until his gray beard brushed Jon’s shoulder.
As the wire bristles scraped the gray-red scale down to bare metal, both men saw the damage at the same instant.
When the royal sappers had sealed the chamber four generations ago, they had not merely bricked up the arch. Before laying the first course of stone, a sapper had struck the central hub and the rim of the two-foot cast-iron wheel three times with a heavy sledgehammer to disable the mechanism without bursting the pressurized water jacket behind it.
