Entry hall 429 deepened the non-Euclidean stonework of the sector, narrowing into a snake-like gallery whose polished hard black rock walls curved in an unbroken S-shaped progression sixty arm-lengths in length.
Here, the sound and sight distortion reached its total peak. A lantern flame held at the southern entrance appeared not as a single amber point, but as six floating yellow crescents that drifted along the curved walls like phantom moons. When Yan Zhiqiu tapped the heel of her boot against the floor flags, the sound echoed as a three-toned chord. Its pitch rising and fell as the sound waves were tightly packed and swelled by the curved surfaces.
Qiao Ming walked five paces ahead, using his twelve-pound lead weight as a sound probe.
He swung the weight gently on two spans of horsehair line, letting the flat lead snout tap the wall every six feet. By the pitch of the returning click, he read the curve of the stone as fluently as a scholar reading a printed book.
“Here is the main focus,” he said, halting at a circular bronze disc eighteen inches across, inlaid flush into the snake-like floor flags.
The disc was engraved with a detailed sharp-angled diagram showing the curved focal lines of the entire gallery. It was marked with sixty-four outward sight-lines that corresponded to the classical trigrams of the First Epoch.
