To balance twelve hundred tons of solid dark rock upon a single bronze lever needed forty thousand gallons of sweet freshwater drawn from the high water tanks of Entry hall 111.
In the high, echoing Balance Vault—situated forty arm-lengths above the clockwork gallery of Sluice Nine—the air was cool. He smelled of wet limestone, crushed slate, and the flat, pure sweetness of limestone-filtered rain. Two huge tube-shaped tanks of hammered sheet-copper, each twenty paces in width and thirty arm-lengths high, hung suspended inside upright shafts cut through the living rock. Above each tank ran four heavy copper delivery chimney pipes, through which water was pouring in twin roaring torrents, foaming white in the darkness as it struck the copper baffles within.
Yan Zhiqiu stood upon the narrow high walkway between the two tanks, her notched hook-blade held ready in her right hand. Beside her knelt eight refugee volunteers from the mining clans, their leather aprons cinched tight, holding heavy bronze drift-pins and wooden mallets.
“Hold the diversion pins!” Yan Zhiqiu shouted over the roar of the rushing water. “Keep the valves open until Caspian gives the sounding! If the east tank fills faster than the west tank by three inches, the balance weight chains will twist on the drums. The whole gearwork will jam!”
