Inside the square granite chase behind the unbolted hatch, the winding gearwork of the King’s Bench air-powered fire-damper was a masterpiece of late seventeenth-century town building. Mounted between two heavy bronze pillow-blocks was a cast-iron drum eighteen inches long and a foot in width, grooved to receive four parallel wraps of three-quarter-inch wire-cored hemp cable. Suspended from those cables, hanging seventy feet down in the dark upright shaft that paralleled Bay Fourteen, hung an eight-hundred-pound tube-shaped metal bar of solid cast iron.
To the left of the winding drum sat the brass trip-cam. A crescent-shaped casting of solid glowing-bronze four inches thick, secured against accidental release by a forged steel keeper-chain whose final link was padlocked to an eye-bolt set into the granite door post. It was this keeper-chain that Orson Pell had locked before leaving the archives, believing that no one could release the balance weight without the master key from his private belt.
Sile Rook knelt before the open hatch. His horn lantern cast a steady, amber light into the grease-blackened inside of the well. He inspected the keeper-chain with the critical eye of an old artilleryman who had set siege winches on the northern frontier. The chain links were forged from five-eighths-inch charcoal iron, rusted red on the surface but sound and ductile at the core. Prying against the padlock with a crowbar would only bend the eye-bolt and jam the links against the bronze teeth of the drum.
