Master Borin Bronze-Lung was sweating through his copper-braided beard. His patience was at an end.
He stood before his brick forge, pumping the hand-lever of a double-chambered leather bellows with wild, jerky strokes. Across the anvil, two High Timber apprentices held an eight-pound bloom of forged iron in heavy gang-tongs. It waited for the metal to reach welding heat.
The coal bed glowed a furious orange. But as Borin’s arm began to tremble with fatigue, the blast slackened.
The orange dimmed to a sullen, smoky red.
“Blast take it,” Borin growled, throwing the bellows handle against the timber post with a dull thump. “My arms are turned to boiled pudding. You can’t weld heavy plate with hand-leather. It takes three men pumping until their lungs burst just to heat one axle bloom. The blast dies the second you reach for the hammer.”
Giles Croft leaned against the forge shop top door beam, sipping a cup of hot parsnip broth.
“Hand-pumped bellows have an effective duty cycle of thirty-five percent,” Giles observed calmly. “Pawn stamina degrades faster and faster under sustained manual hard effort. You’re trying to run a heavy-duty forge on living muscle power.”
Borin wiped a mixture of sweat and coal dust from his bald scalp, his small dark eyes blazing in the gloom.
“And what else am I supposed to run it on, Lord Giles?” the dwarf demanded. “A captured wind demon?”
“High-pressure head pressure,” Giles said, walking into the shop. “We have the River Skell running forty feet away at seven feet per second. We have the timber water chute from the fish weir. We’re installing an undershot water wheel and a twin-metal tube double-acting wooden box bellows.”
Borin stopped, his mouth hanging slightly open. “A water bellows? Wood doesn’t pump air, Giles. It leaks through the seams.”
“It doesn’t leak if you machine the piston faces true and pack the rubber rings with animal fat-soaked wool felt,” Giles replied, unrolling a blueprint across the cold anvil. “A six-foot undershot paddle wheel mounted in the water chute channel. A wooden camshaft with two offset lobes. As the wheel turns, the cams drive two box-shaped pine pistons in alternating set.”
Caleb Thorne-Wood, who had followed Giles with his framing square, leaned over the sketch.
“Two pistons?” Caleb asked, tracing the push-rods. “Like two men taking turns on a saw?”
“Exactly,” Giles said. “Double-acting. Piston A is on the squeezing stroke. Then, piston B is drawing fresh air through leather flapper valves. The air feeds into a common high-pressure surge chamber weighted with flat stones. That delivers a nonstop, non-pulsing blast of four hundred and fifty cubic feet per minute. Zero dead time. Zero arm fatigue.”
Borin’s beard bristled with sudden understanding. “A blast that never sleeps... Ancestors above. What about the nozzle? The iron tuyere pipe melted last Tuesday when we hit twenty-one hundred degrees.”
“No iron tuyere,” Giles said. “We fire a custom heat-proof nozzle from high-alumina kaolin clay, mixed with twenty percent crushed quartz grog to resist heat shock. Angle the nozzle fifteen degrees downward directly into the center of the carbon bed. That directs the forced oxygen into the burning core, maximizing carbon monoxide rusting.”
Borin stared at the drawing for three long seconds. Then he slapped his massive, calloused palm against his leather apron.
“Caleb,” the dwarf rumbled, his voice filling the shop. “Fetch the clear white pine planks and your sharpest planes. Giles, where do we dig the clay?”
* * *
The search for kaolin clay took Toby Karr and four tunnel diggers half a mile up the river gorge.
They found a clean white deposit exposed along the eroded undercut of the northern bluff, beneath a bed of decomposed granite. The clay was smooth as cold butter, free of iron staining, with a soapy texture that promised high plasticity.
Back at the forge, Borin dried the clay on iron plates over the slack fire, crushed it into powder with an iron pestle. Then it sifted it through fine brass wire cloth.
Giles supervised the grog mixture. Eighty parts dried kaolin, twenty parts crushed white quartz sand calcined at red heat.
“The grog prevents shrinkage cracking during the firing cycle,” Giles explained to Toby, who was kneading the stiff paste on a flat slate slab. “Pure kaolin shrinks fourteen percent during dehydration. The quartz grains maintain space-folding balance. Shape the nozzle with an inside venturi taper, two inches at the inlet, necking down to three-quarters of an inch at the orifice.”
Borin molded the heavy clay cone with thick, gentle fingers, smoothing the bore with a peeled animal fat dowel. He set the nozzle into a small annealing box packed with warm charcoal embers. That let it bake slowly into glassy fine china over twelve hours.
Meanwhile, Caleb’s carpentry crew transformed the timber water chute.
They built an undershot water wheel six feet in width, fitted with sixteen outward ash paddles braced with oak splines. The wheel was mounted on an eight-inch square oak axle. That turned inside two heavy pillow blocks lined with cast bronze metal sleeves salvaged from Skag’s wagon.
Inside the forge shop, Caleb erected the wooden box bellows.
The dual box-shaped chambers stood four feet high, built of two-inch white pine planks jointed with tight tongue-and-groove seams sealed with hot pine pitch. Inside each box, a pine piston faced with thick sheepskin fleece moved smoothly along the planed walls.
* * *
Lady Millicent arrived at the water chute platform with her tally-book tucked securely under her cloak. She stood beside Giles. She watched the steady, hypnotic rotation of the oak axle. Water surged over the ash paddles.
“The labor reallocation is already reflecting in the morning ledger,” Millicent remarked, checking her notes. “Earlier, four adult laborers were assigned to eight-hour shifts pumping hand-levers. That was thirty-two man-hours expended daily merely to maintain draft. By replacing human muscle with high-pressure striking force, those four men are reallocated to the charcoal clamp and the quarry.”
“High-pressure power has an uptime reliability of ninety-six percent,” Giles replied. He watched the bronze journal boxes. “Water doesn’t suffer from muscle fatigue, muscle burn buildup, or shift handover delays. Provided the water chute doesn’t freeze solid, the river delivers two and a half clockwork horsepower continuously.”
Caleb was leaning over the camshaft with an oil-can made of hammered sheet copper. He squirted warm animal fat mixed with fine graphite powder directly onto the friction surfaces of the ash cam lobes.
“Listen to that wood slide,” Caleb said proudly. “Seasoned hickory followers riding on oil-soaked ash. The graphite prevents galling. As long as Borin remembers to grease the cams every dawn, this gearwork will turn until the river dries up.”
Borin grunted from the doorway, wiping grease on his apron. “I’ll grease it, wood-carver. Any gearwork that saves my back from pumping leather gets a cup of animal fat every morning and a prayer to the Ancestors at night.”
Outside in the water chute race, Bram and Captain Kroll knocked away the temporary timber cofferdam.
The cold, frothing water of the River Skell surged down the water gate channel.
Creak... Grooosh... Creak...
The water struck the ash paddles with a heavy roar. The massive oak axle turned, gathered driving force. Then he settled into a steady, majestic rhythm of twenty-two turns a minute.
Inside the shop, the offset wooden cams engaged the push-rods.
Hiss-CHUG. Hiss-CHUG. Hiss-CHUG.
The leather intake valves slapped rhythmically against the metal tube ports. The weighted surge box rose four inches on its guide rails. A howling torrent of cold mountain air blasted through the heat-proof clay tuyere.
Borin shoveled three baskets of pure clamp charcoal into the hearth, touched a brand to the coal, and stepped back.
The fire caught with a deep, fiery roar.
Within sixty seconds, the sullen orange glow vanished. The charcoal bed erupted into a blinding lemon-yellow incandescence, then into a pure, shimmering white core that washed the shop rafters in daylight bright glare.
Borin raised his sight disappearing-filament fire gauge to his eye. That turned the brass shift dial with trembling fingers.
“Twenty-four hundred degrees,” the dwarf yelled, his voice cracking with skilled ecstasy. “Twenty-four hundred and twenty! The filament is fully swallowed by the light. It’s the white heat of the great hall of Karak-Thurn.”
He seized a three-inch bar of solid forged iron in his tongs and thrust it into the heart of the flame.
In less than two minutes, the iron emerged glowing semi-clear yellow-white, throwing showers of brilliant sparks like a child’s firework. Borin swung his eight-pound hand-hammer down with a ringing blow.
The two iron bars fused together under his hammer like warm modeling clay. Not a seam. Not a cold shut. A flawless forge weld in a single heat.
“Look at that,” Borin yelled, holding the glowing bar high. “We can forge armor. We can forge giant crossbow axles. We can forge anything the mountain demands.”
Giles nodded, checking the heat reading in his ledger. “The heat-powered upgrade is working. We now have the metalworking needed to make up heavy point-defense munitions.”
“Point-defense munitions, my lord?” Kenneth asked, stepping into the radiant warmth of the forge.
“Aimed fragmentation devices,” Giles said. “We’ll need them. If the Frostblight vanguard arrives with armored units, standard arrows will lack the moving penetration needed to shatter their cryo-matrix.”
Before Kenneth could reply, a sudden, urgent clatter sounded from the narrow high walkway outside.
The shop door flew open, letting in a swirl of sub-zero wind and powdered snow.
Maeve Swift-Ear, the vulpine beastkin scout assigned to high sound surveillance, dropped down from the roof ladder. She stumbled into the shop. She grabbed her curved brass ear-trumpet against her chest, her pointed fox ears pinned flat against her copper hair.
Her amber eyes were wide with primal terror.
“Lord Giles,” Maeve gasped, her chest heaving beneath her fur parka. “The... The earth is speaking.”
Giles set his cup down. “Report, Maeve. Did you detect footsteps?”
“Not footsteps,” Maeve whispered, her voice trembling. “Tremors. Underground blast waves. I pressed the sound-cone against the bedrock of the north cliff ten minutes ago.”
She held up the brass trumpet. The polished metal was humming with a faint, high-pitched shaking that made the coal dust dance on the anvil face.
“The northern ice shelf,” Maeve choked out. “Three miles up the gorge. The glaciers have cracked open. Thousands of claws... Thousands of them, Lord Giles. And behind them, something huge is dragging itself out of the frozen dark.”
The heat inside the forge dropped five degrees in a breath, despite the roaring white-hot hearth.
Giles Croft looked at the shaking brass trumpet, then reached into his coat. Then he pulled out a fresh, flawless sheet of drafting thick parchment.
“The raid timer has sped up,” Giles said, his voice flat, quiet, and fully calm. “Borin. Put down the iron bars. We’re drafting the Claymores.”