The brazing pots burned with a clear, hissing green flame.
Along the crest of the granite dyke, four charcoal fire bowls heated heavy iron irons to a dull cherry red. Master Borin Bronze-Lung wiped a smudge of sharp flux salt across a glowing copper joint, the pungent white smoke puffing into the cold morning air.
“Steady on that sleeve,” Borin barked. He tapped a three-foot length of tubing with a wooden mallet. “If there’s so much as a pinhole in the solder, air will bleed in and kill the draft. A dwarf knows how to seal a pipe against water, but sealing against the sky is another matter.”
Giles Croft stood on the highest shoulder of the hard speckled rock ridge, his wooden ruler extended across the summit bend.
“The maximum theoretical lift for a drain tube at this height is about twenty-nine feet,” Giles said, not looking up. “Our crest is twenty-two feet above the basin water surface. That leaves us seven feet of pressure margin against air-pressure fluctuation. As long as the solder holds, bubbling blast won’t occur.”
Borin grunted, applying a stick of lead-tin wire to the heated joint. The silvery alloy flowed smoothly into the socket, drawn inward by tiny blood vessel action around the entire outer rim.
“Seven feet of sky to spare,” Borin muttered. “I’d rather have three inches of good dwarven bronze.”
Below them, stretched across the face of the dyke, lay three hundred yards of eight-inch copper tubing.
The short intake leg plunged into the foul, yellow-green broth of the sunken basin. It ended in a punched holes in brass strainer basket to keep out weeds. The long discharge leg wound down the northern slope, dropping thirty-four feet into the dry head of the newly excavated drainage canal.
Lady Millicent Croft stood at the base of the work frames, checking the tally of used charcoal sacks against her ledger.
“Each fire bowl has burned through three bushels of hardwood charcoal,” Millicent said. He looked up with her pencil poised. “And the copper billets were valued at forty-two silver sovereigns before Borin started hammering them into tubes. If this pipe doesn’t move water, Giles, you have built the most expensive musical horn in the province.”
“It isn’t a horn, Millicent,” Giles replied evenly. “It’s a passive shifted weight channel.”
Master Caleb Thorne-Wood was bolting the primer pump to a timber cradle at the highest point of the ridge. The pump consisted of two cedar cylinders lined with greased calfskin, fitted with lead-weighted flap valves. A heavy wooden rocker arm connected the twin pistons to an ash running lever.
“It feels like drawing an empty bucket from a dry well,” Caleb said. He tested the rocker with both hands. “No water in the box, no water in the barrel. How can wood pull water up twenty feet of dry copper?”
“The pump doesn’t pull water,” Giles explained, climbing up beside him. “The pump evacuates air. Each stroke removes three cubic feet of air from the crown of the loop. As the internal air pressure drops toward empty pocket, the fourteen pounds of pressure of surrounding air pressing on the basin pushes water up the intake pipe to replace it.”
Caleb shook his head, his hand resting on the ash lever. “Words from a scholar’s book. But if it fails, forty yards of copper are ruined.”
“If it fails,” Giles said calmly, “then Isaac Newton and Evangelista Torricelli were unfit modders. Pump the handle, Caleb.”
Caleb took a deep breath, braced his boots against the granite ledge, and hauled the lever down.
THWACK-CHUG.
The leather seals hissed inside the cedar barrels. A jet of warm, stale air puffed from the top discharge flapper.
Down on the levee, two hundred laborers stood in silence. Toby Karr gripped his chalk-reel, leaning forward so far that Kenneth Drake had to catch him by the collar of his tunic to keep him from tumbling into the canal.
Mistress Pippa held her glass phial with both hands. Her runic heat spindle was tucked behind her ear. Beside her, Master Duncan Stone-Splitter leaned against his sledgehammer, his jaw set in stubborn doubt.
“Nothing,” Duncan called out. “Not a drop.”
“Pump,” Giles repeated.
Caleb hauled the lever again. THWACK-CHUG.
Three strokes. Five strokes. Ten strokes.
The pushback on the wooden handle began to stiffen. On the twelfth stroke, Caleb had to throw his entire body weight onto the bar to force the piston down.
“She’s taking hold,” Caleb gasped, veins standing out on his neck. “The lever feels like it’s hooked to an ox team!”
From deep inside the copper tubing came a hollow, metal gurgle.
It wasn’t the sound of rushing water. It was the sound of air under tension. A long, shuddering whine that shook through the metal brackets bolted into the granite.
“Look at the intake,” Toby shouted, pointing toward the basin.
Around the underwater brass strainer, the dark green scum began to swirl. A smooth, concave depression formed in the water, pulling leaves, twigs, and rotting foam toward the copper pipe.
GLUG.
The sound echoed through the metal. Then, at the summit, the check cock gave a high, piercing whistle as the last pocket of trapped air was drawn out.
“Close the valve, Caleb,” Giles commanded.
Caleb threw the brass petcock lever shut.
For two heartbeats, the entire hillside was dead quiet.
Then, down at the canal outfall thirty feet below, something slammed into the iron flap gate with the weight of a dropped anvil.
KABOOM.
The heavy iron flap blew open on its hinges.
A solid, eight-inch metal tube of black swamp water burst from the mouth of the pipe. It didn’t trickle. It erupted in a roaring, high-pressure jet that shot twenty feet through the air before crashing into the canal trench with an ear-splitting roar.
Yellow foam sprayed forty feet across the clay banks. The water tore into the dry ditch, gouging out silt and churning down the straight canal hall toward the southern riverport.
Duncan Stone-Splitter took one step back, his sledgehammer slipping from his hand and clattering into the grass.
“By the anvil of the world,” Duncan whispered. “The mountain is bleeding uphill.”
Mistress Pippa let out a shrill laugh, dancing three steps in the mud while clutching her glass phial. “Look at it climb! No wheel! No mule! No fire! The water walks over the cliff like a goat on a ridge!”
The assembled laborers didn’t laugh. They backed away from the canal bank, staring up at the gleaming copper pipe with white, scared eyes.
A young ditch-digger from the second gang dropped to his knees, pressing his palms against the mud. “He laid a copper wire upon the stone, and the mountain opened its throat. The Lord Master builder commands the rivers of the sky!”
“Nobody is commanding the sky,” Giles called down from the narrow high walkway, his voice dry and thoroughly annoyed. “It’s a standard drain tube balance. The speed head is twelve feet per second, and discharge is about fourteen hundred gallons per minute. Stop praying to the gravel and clear the downstream silt bars.”
* * *
By late afternoon, the roar of the drain tube had settled into a steady, shaking hum that set the teeth on edge.
Giles stood on the dyke crest with Toby, checking the level marks chalked against the granite face. Water drops ran down the outer surface of the copper pipe in cold, shimmering rivulets. It was drawn from the humid air by the freezing heat of the deep spring water coursing through its belly.
“Fourteen inches,” Toby reported, crouching on the wet stone to read the rule. “The basin has dropped fourteen inches since noon, Lord Giles!”
“The flow rate will decrease slightly as the intake head drops,” Giles said, jotting the numbers into his notebook. “Bernoulli’s theorem dictates that effective head is measured from the basin water surface to the discharge doorstep. As the surface falls, total head declines. But we should drain the upper twelve feet within four days.”
Kenneth Drake walked the lip of the canal, his pacing rod measuring the depth of the new stream.
“The current is running six miles an hour,” Kenneth said, looking back over his shoulder. “If Baron Cedric sends men up the canal bed to harass our diggers, they’ll have to wade against a mill-race. A ditch with water moving this fast is as good as a wooden wall.”
“Better than a wooden wall,” Giles noted. “A wooden wall needs sentries and rots in the rain. Moving water provides passive defense and flushes the bottom silt at the same time.”
Across the sunken basin, the transformation was already visible.
The wide, oily expanse of green water was shrinking away from the rocky margins. Mud flats coated in grey silt and rotting pondweed were baking in the afternoon sun. It cracked into broad six-sided tiles. The stench of decomposing marsh vegetation was thick. But Sister Teresa’s crews were already moving along the banks with spray lances, laying down a white carpet of burning lime powder to suppress the odor.
“Look there,” Torvald Dune-Strider said, stepping up beside Giles.
The desert chieftain was pointing toward the center of the receding lake. There, the water had cleared from a shallow shelf.
Beneath the swirling silt, something massive was emerging from the deep.
It wasn’t a ridge of natural stone. Rising through the receding water were two huge parallel walls of dressed, dark green red stone, twenty feet apart and curving gracefully toward the northern mountain pass.
Between the walls stood a majestic series of stone arches, underwater for hundreds of years beneath the marsh, their keystones carved with deep, sharp-angled linked knotwork.
“That’s not natural,” Toby whispered, lowering his chalk-reel. “Look at the joints. They’re straight. Dead straight.”
Giles took his sighting scope from its tripod and sighted down the line of the arches.
“Sixteen-foot span,” Giles muttered. “Three-centered basket-handle arches. That’s not medieval frontier work. The stone is dressed to a sixteenth of an inch. The piers are laid with high-pressure volcanic cement mortar.”
Borin Bronze-Lung pushed his way through the scrub, his brass fire gauge swinging against his chest. He stopped at the edge of the granite ridge, his eyes locking onto the underwater stonework.
His mouth fell open. His braided copper beard began to tremble.
“The Sunken Way,” Borin choked, his voice cracking into a dry croak. “The High Gate of Khaz-Drak. By the seventy ancestors of the mountain... It was never crushed. It was only drowned.”
Kenneth Drake squinted into the shadowy cave opening beneath the central arch. “If that road leads under the mountain, my lord, anyone holding the other end can walk an army right into our back garden.”
“An eighteen-foot vaulted underground highway,” Giles said, closing his notebook with a decisive snap. “Solid rock foundation, covered transit, zero snow buildup, and a direct grade into the stone basin. If an army wants to march down it, they will find it much easier to pull wagons of kaolin clay and coal instead.”
He turned toward Borin.
“Borin, sharpen your pry-bars and bring up the fish grease. We have a gate to unstick.”