Beyond the silent ranks of the iron sentries, the floor of the Fourth Century dipped sharply downward into a humid, roaring cave chosen as Entry hall 423.
Here, the quiet, dry cold of the upper galleries was replaced by the ear-splitting, physical fury of active water. The hall was a titanic high-pressure channel twelve arm-lengths wide, carved through the solid hard black rock bedrock of the lower hull, its walls lined with curved plates of dark green bronze clamped with six-inch copper studs.
Down the center of this hall ran the Great Siphon of the Fourth Sector.
It was a tube-shaped bronze channel eight arm-lengths in width, suspended four feet above the floor flags by massive iron cradles anchored into the bedrock every six paces. The metal skin of the channel was weeping—sweating cold water drops that dripped steadily onto the floor with a nonstop, drum-like patter that mingled with the roaring rush of seawater within the pipe.
Qiao Ming stopped at the entrance doorstep, his bare feet planted wide upon the wet hard speckled rock flags. He inhaled deeply, savoring the familiar, sharp bite of raw deep-sea salt water and cold iodine that filled the air.
“The Fourth Siphon,” he announced, raising his voice to carry over the underground roar of the water. “It draws water directly from the outer trench at Fathom 120, circulating forty thousand gallons of high-pressure salt water per minute through the lower cooling drain pits of the Ark’s dormant engines before discharging into the…
