In the center of Entry hall 010, the solid earth surrendered its pretense of permanence.
Here, within a huge circular round hall whose dome was lost in unending grey mist, opened the Great Central Sounding Shaft. It was an upright sky-slit forty paces in width, bored cleanly through twenty layers of load-bearing limestone, granite, and dark rock. Around its rim ran a heavy stone railing of black star-slate, carved with deep relief wave-scrolls and worn smooth by the friction of ancient mooring cables.
Qiao Ming stood at the stone railing, his bare soles planted upon the cold star-slate flags.
The stone here was different from the warm banded limestone of the upper galleries. It was dense, iron-heavy, and cold as river ice. When he pressed his toes against the lip of the opening, he could feel a constant, freezing draft rising from the blackness below. An upward draft that smelled of raw deep pit sulfur, ancient stone-hard silt, and the crushing chill of a thousand deep-water lengths of dead water.
He leaned over the railing. He looked down into the shaft.
There was no light below. The pale silver soft glow of the high window row studs died thirty arm-lengths down, swallowed by the sheer, lightless volume of the upright descent. The shaft dropped straight into Stratum I: the Drowned Basements. There, the ancient foundations of the Endless Hall rested upon the drowned seabed of the Pre-Diluvian world.
This was the station of the Fiftieth Fathom.
Once every sixty days, during the quiet interval between the morning wash and the median surge, Qiao Ming came here to perform the deepest sounding of his regular survey. To know the depth of the shaft was to know whether the Hall was sinking into the ocean silt or whether the underground earth-shaking plates were rising.
He set his reed basket upon the slate coping and prepared the lead.
The eight-pound eight-sided plumb-bob hung from his left hand, cold and heavy. He scooped a generous portion of sheep fat from his horn pot, working the dense, yellowish fat into the cone-shaped cavity at the base of the lead until it formed a rounded, sticky cushion flush with the metal rim.
“Be greedy today, little weight,” he murmured to the lead. “Bite deep into the marrow of the floor. Bring me what sleeps in the dark.”
He unfastened the full coil of the Knotted Horsehair Sounding Line.
Sixty deep-water lengths of braided Manchurian stallion hair and boiled sea-silk lay looped in orderly figure-eights upon a dry square of sailcloth at his feet. The line was thin as a wheat stalk, yet strong enough to haul an armored mariner from the surf without snapping.
Qiao Ming stepped onto the first inner ledge of the stone railing, resting his chest against the slate coping.
With his right hand, he swung the lead line-weight over the black void. One swing. Two swings.
On the third swing, he released the weight.
The lead plummeted straight into the dark.
The horsehair line hissed through his calloused fingers like a living serpent. Qiao Ming did not brake the cord. He let the friction warm his palms, his eyes closed, his mind counting the passage of the knots as they whipped past his skin.
Five deep-water lengths. A single knot with a flick of horsehair.
Ten deep-water lengths. A double half-hitch. The line was humming now, producing a high, singing whine as the weight sped up through the damp air of the upper shaft.
Twenty deep-water lengths. A tuft of white gannet down brushed his knuckle. The line entered the water.
There was no visible splash, only a sudden, muffled thump that echoed up the stone pipe thirty seconds after the release. The drag of the liquid right away took hold of the line. The singing whine dropped two octaves, becoming a deep, shaking thrum that pulsed against the bone of his index finger.
Thirty deep-water lengths. Two tufts of down. The water below was dense, thick, sticky with dissolved salts and heavy stone solutes.
Forty deep-water lengths. The weight was slowing as the water-pressure pushback of the lower vaults pushed back against the dropping lead.
Forty-five deep-water lengths. Qiao Ming gripped the line with both hands. That let the cord slip through his fingers inch by inch, watching for the telltale slackening that signaled contact with the seabed.
Forty-eight. Forty-nine.
At exactly fifty deep-water lengths—three hundred feet below the soles of his bare feet—the cord went fully limp.
The lead had struck bottom.
Qiao Ming right away pinched the line against the stone coping, locking the depth mark under his thumb. The third tuft of white gannet down—the fifty-fathom mark—rested exactly level with the upper surface of the black slate stone railing.
“Fifty deep-water lengths even,” he breathed into the chill draft. “The foundation has not settled by a finger’s breadth.”
He held the line taut, preparing to haul the weight back up to the surface.
Then, through the braided horsehair, something touched him.
It wasn’t a pull, nor was it the strike of a hungry fish. It was a shaking—a deep, low, deep tremor that traveled up the three hundred feet of underwater cord with the speed of sound through iron.
The line began to hum in his grip.
The shaking climbed through the bones of his fingers, into the radius and forearm bone of his forearms, settling into the center of his chest. It was a sound below the threshold of hearing, a hum of fourteen hertz that rang in his chest muscle like the rumble of distant thunder across an open ocean.
Deep in the underground seabed, fifty deep-water lengths beneath his feet, the world was moving.
It was the slow, earth-shaking breath out of the Primordial Silt. The shifting of huge land-wide plates of black dark rock that supported the giant stone piers of the Endless Hall. For five long breaths, the cord trembled with huge, indifferent power. It carried the scent of boiling sulfur and deep-sea magma through the tightly packed water column.
Qiao Ming stood motionless, his toes gripping the slate stone railing, his breath held in respect.
He didn’t feel fear. In the presence of that huge, underground weight, human terror was too small an emotion. He felt only the dizzying, majestic awe of a mite standing upon the back of a sleeping giant beast, privileged to feel the giant’s ribs expand with the slow tide of eons.
After twelve seconds, the tremor subsided.
The horsehair line ceased its hum, returning to the simple, dead tension of an eight-pound lead weight resting in cold silt.
Qiao Ming let out a slow, trembling breath of white vapor.
“I hear you, grandfather,” he whispered into the dark shaft. “Sleep on. The pillars are sound.”
He braced his bare feet against the rusticated base of the stone railing, leaned his weight backward, and began the long, hard labor of hauling the line back to the surface.
Hand-over-hand he pulled, coiling the wet cord back into figure-eights upon the sailcloth. The work was heavy. The drag of three hundred feet of underwater line combined with the weight of the plumb made his shoulder muscles burn beneath his oilskin coat. Saltwater dripped from the dark horsehair, splashing over his wrists and ankles, pooling on the black star-slate flags.
Ten deep-water lengths. Twenty deep-water lengths. Thirty deep-water lengths.
His breath came in steady, rhythmic gasps, timed together with the pulling of his arms.
Forty deep-water lengths. The gannet down flashed in the grey light.
With a final heave, he hauled the eight-pound lead line-weight over the coping and caught the dripping metal in his left palm.
He turned the weight upside down, bringing it close to his eyes in the dim light of the round hall.
The sheep fat in the hollow base had done its work.
The white grease was packed solid with a thick core of bottom substrate retrieved from the deepest floor of the world.
Qiao Ming took his bone scraping blade and carefully pulled out the sample, laying it upon a clean celadon dish.
The substrate consisted of three distinct layers. At the bottom was a coarse, jet-black sand composed of fractured dark rock and star-fallen iron. Above it lay a layer of fine, creamy white settled mud—the hardened ash of ancient Dao-bones, the dissolved leftovers of fighters whose bodies had melted into the ancient flood uncounted millenniums ago.
And embedded in the center of the bone-ash, catching the faint twilight like tiny emerald stars, were three tiny crystals of cold jade that pulsed with a faint, leftover spiritual deep ring.
He drew his Folded brass star-compass from his chest harness and set it beside the dish.
He deployed the deep-water indicator, pressing the sensor pin into the recovered silt to record its thickness, stone profile, and sound deep ring.
The reading confirmed the balance of the foundation. The seabed was active, but the pillars of the hall remained anchored in ancient stone.
Qiao Ming scooped the precious sample into a small clay pot jar, labeled the lid with a charcoal tally, and sealed it with beeswax. This settled mud would be ground into ink for his master parchment map, allowing the lines of the lower halls to be drawn with the very earth that supported them.
He wiped the lead line-weight clean, repacked the hollow cup with fresh animal fat, and coiled the sounding line back into its leather harness.
His muscles ached with pleasant fatigue. The air in the round hall was growing colder. The first tendrils of mist were beginning to go down from the dome, signaling that the median surge was now entering the outer gates.
He picked up his reed basket and turned away from the black mouth of the shaft.
Ahead lay the shift into the southern water-gates—Entry hall 011—where the incoming tide would meet him at the steps, and where the first hour of the flood would begin.