Entry hall 442 was the care toolroom of the Fifth Century, an intimate vaulted chamber whose walls were lined with cabinets of dark, stone-hard bitter pine-resin wood whose drawers still held hundreds of fine slate files, agate burnishers, and bone polishing sticks.
In the center of the room stood an ancient lapidary treadle lathe carved from a single block of white Carrara marble.
The lathe was powered by a heavy wooden flywheel weighted with lead plugs around its rim, connected by an oiled leather belt to a bronze chuck that could hold small metal components with zero run-out. The bed of the lathe was fitted with an adjustable bronze tool-rest, notched with hair-thin division marks that allowed a workman to advance a cutting tool by a thousandth of an inch with a single turn of a knurled thumb-screw.
Qiao Ming sat upon the low ash stool before the lathe, his bare feet resting lightly upon the wooden treadle.
He placed the first glowing-bronze gear wheel—a four-inch idler with thirty-six teeth—into the bronze chuck. He tightened the three clamping jaws with an iron key until the wheel was centered to within the thickness of a spider’s thread.
Beside him, Yan Zhiqiu set her lantern on the tool-rest, its focused amber beam lighting up the bronze teeth in sharp relief against the dark marble bed.
