The three-thousand-foot coil of star-thread line was carried into Entry hall 729: The Knotting Floor. This was a huge metrological gallery whose floor was composed of a single, nonstop runway of polished white Pentelic marble, sixty arm-lengths long and four arm-lengths wide. Embedded in the marble was the Master Land-mapper’s Rule: a nonstop bar of gold-trimmed bronze, graduated in feet, arm-lengths, and deep-water lengths.
The Primordial Fathom of the First Mapmakers was exactly six feet. The natural armspan of an adult water mapper with his shoulders squared and his fingers extended. To mark this line was a sacred metrological ceremony. Each fathom had to be measured under standardized tension, knotted with the traditional maritime knot. Then he sealed with colored thread and thick tar to ensure zero drift under deep-sea deep water pressure.
Qiao Ming and Yan Zhiqiu began at the zero-mark. The running end of the cord was fitted with a heavy bronze thimble—a teardrop-shaped eyelet lined with glowing bronze, designed to receive the mid-air loop of the eight-sided lead line-weight. Qiao Ming seized the thimble into the cord with sixteen turns of waxed sailmaker’s twine, using his True-Sight Needle to tuck the ends through the core of the braid.
