The ascent from the Primordial Sump was an entirely different journey from the choking descent forty-eight hours before.
Lin Tao and Tie Shan climbed the three-thousand-foot iron spiral stair. Then, the air in the upright shaft was no longer a heavy, sulfur-choked fog of heat and decay. It was cool, crisp, and alive with the refreshing scent of mountain snowmelt and sweet pine, pulled down through the Precursor air-flow ducts by the powerful high-pressure draft of the restored pumping grid.
Along the shaft walls, the ancient copper channels that had been shuddering with chaotic a deep hum bubbling blast tremors were now fully silent. It hummed with a gentle, unified carrier wave that felt like the purr of a well-oiled clockwork engine.
At the top of the stair, the heavy star-iron door of the Seventh Hearth sub-basement stood slightly ajar.
Lin Tao pushed the iron door open with his left hand. He stepped through the threshold onto the dark rock flags of the outer fire gallery.
The roaring torrent of sapphire water thundering through the Seventh Hearth water chutes had washed away thirty years of piled up melted rock waste dust. That left the dark stone channels gleaming with a clean, polished luster. The air in the foundry was so clear that the high window row windows sixty feet above cast bright, clear beams of morning sunlight across the stone floor, lighting up the cheering faces of the laborers in brilliant, warm gold.
