Entry hall 427 was a cavernous drainage castle wall whose floor was dominated by six massive circular scupper-wells, each four arm-lengths in width, covered with heavy grates of forged glowing-bronze.
The air here was foul, choked with the acrid stench of burned sulfur, boiled away burning acid, and scorched stone grease drifting through the southern portal from the ruined machines in the last hall. On the floor flags, thin streams of black machine lubricant and yellow acid-water were beginning to trickle southward, threatening to seep into the lower domestic vaults if left uncontained.
Qiao Ming walked to the eastern inner wall of the castle wall, where a massive cast-iron sea-valve wheel eight feet in width was mounted flush against the living hard black rock.
The wheel was connected to an ancient high-pressure high-pressure water gate that tapped directly into the external sea-chest at Fathom 120. Above the wheel, a stone carving was carved into a bronze plate: The Cleansing Siphon of the Fourth Keel. Turn three revolutions to purge the floor.
Qiao Ming set his reed basket upon a dry cut stone ledge and turned to Yan Zhiqiu.
“Climb to the upper narrow high walkway,” he commanded. He pointed his boxwood measuring rule toward an iron overhead frame bolted twelve feet up the western wall. “When I trip this sea-valve, sixty thousand gallons of high-pressure deep-sea salt water will erupt from the overhead flushing chimney pipes. The water will sweep across this floor at hip height, scouring every trace of…
