In Entry hall 135, the floor was not anchored to the earth.
The Causeway of Balanced Slabs stretched two hundred paces across a lightless deep pit of black salt water forty deep-water lengths deep. The path was five paces wide, composed of seventy-two box-shaped slabs of dark phonolite, each three arm-lengths wide and five arm-lengths long, floating upon underground high-pressure pistons filled with dense, stone-rich salt water.
There were no handrails. There were no stone railings. On either side of the raised stone road, the black water of the lower sump vanished into the lightless gloom below, its surface still and silent as molten glass.
Qiao Ming stood at the eastern bridge pillar, his bare feet resting upon the solid bedrock doorstep.
He lowered his horn lantern, shining the beam along the margin of the first slab.
The phonolite slab was floating. It rested half an inch above the next-door rock, suspended upon a thin film of high-pressure fluid that hissed softly through micro-tiny blood vessel relief valves drilled into the outer edge seams. As the draft from the western chimney pipes brushed across the raised stone road, the slab tilted by a fraction of a tiny fraction of an inch. Its bronze dampers murmured with a low, metal hum as they corrected the balance.
