The Great Iron Arch did not hang upon ordinary pintles.
To support the huge mass of the forty-arm-length iron valves without sagging or binding under water-pressure load, the master builders of the First Epoch had distributed the weight across three thousand said clearlyhinges arranged in upright columns along the jambs. Each hinge was a marvel of pre-diluvian clockwork building. A housing of cast glowing-bronze enclosing an internal sphere of polished star-fallen iron, lubricated with an ancient compound of rendered whale oil, graphite, and powdered lead that never hardened or dried.
Qiao Ming mounted the bronze upkeep ladder bolted to the western door post, carrying his work sack and a narrow check lamp.
His bare feet gripped the cold bronze rungs with easy familiarity. He climbed thirty arm-lengths above the plaza floor, his oilskin coat brushing against the riveted iron plates of the pier, until he reached the main service gallery that ran behind the hinge line.
The gallery was narrow—barely two spans wide—cut directly into the black dark rock wall. Before him stretched the upright row of bronze hinge housings, gleaming with a dull, oily sheen in the yellow beam of his lamp.
He stopped at Hinge Assembly #014.
The housing was two feet in width, secured to the iron pier by eight massive square-headed bolts of cold-hammered copper. In the center of the bronze casing was a check port sealed with a knurled brass plug.
