Dropping twelve arm-lengths beneath the artillery gallery, Qiao Ming and Yan Zhiqiu entered Entry hall 736: The High-Pressure Accumulator Vault. This was a low-ceilinged, fortified chamber blasted out of solid gabbro bedrock, designed to contain the huge air-powered potential that powered the clockwork systems of the Submerged Bastion.
Arranged along the centerline of the vault were three huge tube-shaped storage tank tanks of forged iron, each twelve arm-lengths long and four arm-lengths in width. The iron vessels were banded with heavy hoops of hammered bronze every two spans, bolted to massive stone granite cradles set deep into the foundation stone. A network of heavy copper spreading pipes branched from the tank headers, padded with tar-soaked hemp canvas to prevent heat water drops.
Qiao Ming walked between the massive iron cylinders, his bare horn-hard feet sensing the subtle, high-hum sound hum shaking through the bedrock floor. The air in this chamber was dry and charged with the faint, crisp scent of tightly packed ozone and stone oil. He approached the master pressure gauge mounted on the main pipe hub.
The gauge was a masterpiece of First Epoch instrumentation: a circular dial of white fine china sixteen inches in width, protected by a domed lens of rock crystal and bound in a heavy glowing-bronze bezel. The bronze pointer rested steadily upon the red line: one hundred and eighty bar of static air-powered pressure.
