To understand why the House had endured when the stars themselves had burned out, one had to examine the mathematics of its outer shell.
After the afternoon meal, Qiao Ming led Yan Zhiqiu to the eastern wall of Entry hall 003. There, the smooth soapstone met a massive upright pilaster of dark, crystal-clear dark rock three arm-lengths wide.
On the face of the dark rock, ancient stonemasons had carved a building cross-section of the sector, rendered in the precise intaglio relief of the First Epoch. Beside each stone-built layer, ancient tally marks recorded the thickness of the stone, the crushing strength of the mortar, and the maximum water-pressure load the inner wall could sustain before developing deep wear.
“Look closely, record-keeper Yan,” Qiao Ming said. He held the small animal fat lamp near the stone face so that the golden light caught the incisions. “Your pursuer carries void-borers with diamond heads. But how thick does he believe our walls to be?”
Yan Zhiqiu stepped closer, her bare soles cold against the flat stone slabs, her fingers tracing the carved diagram of the seawall.
Her eyes, trained to read stone-built schematics with royal speed, followed the nested layers of defense.
“In the outside world,” she said, her voice filled with mounting shock, “the thickest castle walls in the royal capital were twenty arm-lengths of heavy granite. A standard void-borer could chew through twenty arm-lengths in four hours.”
