The cold that inhabited the upper halls began to yield to a dry, lingering heat shadow as they crossed the threshold of Entry hall 658. This was the Melted rock Pillar hall, a vast underground cave whose dimensions exceeded any hall they had crossed since leaving the central rows of stone pillars of the First Epoch.
Dominating the center of the hall stood four giant stone blast furnaces, tube-shaped iron monsters towering sixty arm-lengths from the floor plates to the vaulted granite ceiling. Their outer mantles, forged from curved sheets of riveted boiler plate four inches thick, were bound with heavy circumferential bands of forged star-fallen steel. The heat-proof brick linings visible through the blown-out check ports were fused into a nonstop, greenish glaze of glass-fused quartz dust, scarred by the infernal heat of long-extinct smelting cycles.
Qiao Ming climbed the narrow spiral stair of cast iron that wrapped around the flank of Furnace Two. His bare calloused feet gripped the punched holes in treads with practiced, prehensile ease. The metal was pitted and coated in a fine layer of dry hematite dust that stained his soles dark crimson. At forty-eight arm-lengths above the floor plates, he stepped onto the fourth-tier charging narrow high walkway, leaning out over the iron safety rail.
