At the exact center of the Eighty Courtyards, buried ninety deep-water lengths beneath the central nave of Entry hall 045, lay the Acoustic Keystone of the Ark.
Here, in a circular chamber carved from a single nodule of dark green jade, the master sounding chimney pipes of all eighty entry halls came together into a single upright sound shaft eight arm-lengths wide. Every breath, every whisper, and every footstep taken upon the forty thousand cut stone terraces above traveled downward through the hollow pale limestone foundation ribs, focusing into this room like the sound chamber of a huge cello.
The chamber was suspended upon forty-eight massive naval bronze tension cables anchored to the land-wide bedrock, isolating it fully from external ground-shaking rumble and clockwork shaking. Only the true internal deep ring of the living structure could reach its polished green jade walls.
It was midnight—the hour of the Slack Water. In the courtyards above, the lamps had been dimmed to tiny green embers, and ten million mortals lay asleep upon their rush mats.
Qiao Ming stood alone upon the central green jade stone stand, barefoot, his body stripped to his linen trousers and oilskin harness. Yan Zhiqiu sat upon the low stone bench beside the entrance archway, her shale slate balanced on her knees, her soapstone pencil poised in total stillness.
