Ezra arrived at the site of the Blast Furnace early morning. Halvork was finishing up with firing up the kiln.
At the base of the tower, dozens of soot-stained workers moved, carrying iron rods, buckets of sand, and stacks of raw timber.
Men hauled the iron ore into place. They were placed in wheelbarrows. Unlike a similar era counterpart on earth, the Imperium had already developed the concept of a wheelbarrow. Worker upon worker kept on delivering the ore toward a stockpile. Some laborers were on standby waiting for the signal to shovel them into the furnace.
The scale of the operation was massive. The work yard, situated next to the river, had been stripped of grass and brush by the constant march of boots. The blast furnace itself towered over them. Thirty feet of stone, banded at regular intervals by riveted iron straps designed to keep the structure from bursting under its own internal pressure. Imperial concrete had been poured around the structure.
Before approaching the master craftsmen, Ezra walked along the furnace just to perform an visual inspection. He activated AMP. He knew he didn't need to, he did this last week and the week before. But something in him just wanted that visual feedback and complacency. His small boots crunched as he walked toward the staging area.
He stopped at the wooden pens that formed a semicircle around the tower. The iron ore was piled to the left while the charcoal sat in the center, and the crushed limestone was stationed on the right.
The three lead guildsmen who headed the project stood waiting for Ezra.
"Master Surveyor, Master Smith, Kilnmaster," Ezra dipped his head.
The three Masters bowed to Ezra. "Lord Ezra."
Albrecht stepped forward. "Do you find that all is in order?"
Ezra nodded.
"The materials are sorted, Lord Ezra," Albrecht reported, holding up the board. "Everything has been passed through the sizing grates. No pieces larger than a man's fist, just as instructed, to ensure the air can flow through the burden. According to Master Faraday's notes."
One of the reasons this project was greenlighted was because Ezra had mentioned that this was notes from a certain Michael James Faraday. Draffen, Corvin and Kestel were all fond of this "Master" especially that he was the author of the books Fundamentals of Arithmetic and Fundamentals of Accounting. Draffen had also personally endorsed this to Reitz once he understood that it was from "Master Faraday's" notes.
Ezra inspected the grated piles. Once he saw that everything was uniform. He gave a single nod and continued his walk, heading down the sloping bank toward the Nier river.
A colossal waterwheel sat seated deep in the river. Ezra's eyes traced the axle extending from the wheel into the mechanical housing. A standard blacksmith's forge relied on a man pumping a bellows, creating an inconsistent breath of air. A blast furnace required a continuous draft. If the air pressure dropped for even a second, the heat inside the belly would fluctuate and ruin the melt.
To solve this, Ezra had drafted a specific regulating mechanism. Attached to the main axle was a stone flywheel. It was designed to store kinetic energy, smoothing out the stuttering rotation of the river water wheel. As the flywheel spun, staggered wooden cams engaged alternating levers.
The few times Draffen had gone to the site. He could hear Draffen mutter "genius" under his breath. Draffen had inspected the mechanism carefully before the final installation.
Ezra looked past the cams to the twin, leather bellows that were big enough for carriages. Because the cams were perfectly offset, one bellow would compress and blow while the other was lifting and inhaling. The alternating rhythm ensured an unbroken gale of air blowing continuously.
Albrecht caught Ezra's eye which looked at the water wheel and the flywheel.
"Brilliant isn't it? According to Master Faraday in order to make the motion of a wheel stable, we can apply this principle. The potter wheel already does this, he just transferred that knowledge to something broader.
Ezra flared mana just so that he wouldn't blush. He nodded in acknowledgement.
Ezra's eyes traced the iron pipes—the tuyeres—leading from the bellows directly into the lower stone belly of the furnace. Layers of heat-resistant clay sealed the joints made of iron, packing them tightly so the pressure wouldn't bleed out.
Satisfied with the reinforcement Ezra turned and walked up the embankment toward the base of the structure just checking the tolerances and the forces acting on the base.
Ezra looked again at Arran, who after bowing already his sights on the first firing of the kiln. He and the kilnmaster were already at work. Even though Arran's face wore a permanent frown. There was a peculiar shine in his eyes that was child like.
Ezra moved closer. He already hear him shout.
"Is the kiln warm enough? Has it dried?" Arran shouted to the Kilnmaster, so that he could hear him. He looked up at the imposing structure with a certain awe and reverence.
Halvork pointed his thumb toward the bottom of the furnace, where a small, glowing fire had been maintained inside the open taphole. "We've kept a slow fire breathing in the hearth for three days and three nights. The damp is completely burned out of the mortar. The belly is baked through, so the stone won't burst when we feed it the real heat."
"And lighting the main fire?" Arran shouted again as his eyes darted from the ore to the kiln.
"Once the stone is baked through, we feed her," Halvork answered, his arms crossed over his chest and his eyes lightly squinting. "No iron yet. Just charcoal and lime. We let it catch naturally until the belly is hot enough to melt rock. Only then do we drop the sluice and let the river take the wheel. When the flame at the top burns white, we give her the iron."
Ezra listened to the breakdown. It was the correct procedure. They understood the necessity of the alternating air blast, and the danger of thermal shock.
He gave a single, satisfied nod and stepped back to the perimeter.
Arran's face cracked into a grin. "Proceed."
The single word was the trigger the yard had been waiting for.
Halvork immediately signaled a team of men standing near the base of the hearth. They moved quickly, hauling buckets of wet clay. Using long trowels and their gloved hands, they packed the lower taphole, sealing the belly of the furnace to trap the heat. They left only the angled iron tuyeres open.
Up on the spiraling wooden scaffolding that wrapped around the outer stone shell of the tower, the waiting laborers sprang into motion. They gripped the wooden handles of their wheelbarrows, the iron wheels clacking against the timber ramps.
"Blank charge!" Albrecht shouted from the bottom, pointing his stylus. "Charcoal and lime! Move it up!"
The laborers began tipping their wheelbarrows, dumping massive loads of black charcoal and crushed white limestone directly into the open mouth at the top of the tower. Dark dust plumed into the morning sky, coating the sweating workers in a fine layer of gray grime. The hollow, echoing thuds of the materials hitting the deep interior of the furnace rang out across the yard.
It took over an hour of labor just to fill the lower belly. Down in the casting yard, Arran directed a different crew. They prepared the ground where the molten iron would eventually flow. Using specialized rakes made of wood, the men shaped a bed of sand. They dug a central channel leading away from the furnace base. Branching off this main channel at right angles were dozens of smaller, molds pressed into the sand. To the workers, the shape looked like a mother pig nursing a litter of piglets.
Once the belly was sufficiently loaded and the sand beds were prepped, Albrecht waved a bright red flag toward the riverbank.
A specialized crew heaved their collective weight against a heavy wooden lever system. With a grinding groan of wood and iron, the heavy sluice gate lifted.
Water from the Bren river rushed through the diverted channel. It surged forward, catching the broad wooden paddles of the massive undershot wheel. The heavy timber groaned under the sudden torque.
The wheel began to turn, picking up a steady, rhythmic speed. The massive flywheel engaged, storing the momentum and ensuring the rotation was perfectly smooth. The staggered cams rotated upward, pressing down on the alternating levers.
Thwump. Creak. Thwump. Creak.
Because of the offset cams, the twin bellows took turns compressing. The result was exactly as Ezra had designed: a seamless, pressurized, continuous gale of oxygen blasting through the tuyeres directly into the hearth.
The furnace roared to life. A pillar of black smoke, quickly followed by a jet of orange flame, erupted from the chimney at the top of the tower.
The ground literally vibrated beneath Ezra's boots. The low, rumble resonated in the chests of everyone standing in the yard, entirely drowning out the shouts of the workers.
Hours ticked by. The sun climbed higher into the sky, but its heat engulfed by the heat seeping through the stone walls of the tower. The air in the yard warped and shimmered, distorting the shapes of the men working near the base as if you were looking through a hot day in the dessert.
Arran stood close to the structure, his eyes squinted against the glare, keeping an eye on the fire shooting from the top. As the morning shifted into midday, the smoke began to clear. The fire changed. The bright orange shifted into a pale yellow, and then, slowly, into a transparent blue-white.
"Start the load!" Arran barked, his voice barely cutting through the deafening hum of the waterwheel.
The laborers sprang into action. Wheelbarrows came up to the wooden ramps in an endless rhythm. Albrecht stood at the base of the ramp. He didn't have much to do once the structure was finished but he really wanted to see the final result of the new forge. They maintained the strict ratios that were mentioned in "Master Faraday's" notes.
Three barrows of ore. One barrow of limestone. Three barrows of charcoal.
Charcoal, limestone, and jagged iron ore were tipped into the maw.
Inside the stone belly, the temperatures exceeded that of a regular kiln. The limestone melted first, turning into a liquid flux that captured the rock, ash, and all the impurities clinging to the iron ore. A slag formed from the mixture. The iron ore itself, subjected to heat and e gas, was stripped of its oxygen. It liquified into metal, sinking through the lighter slag to pool at the very bottom.
Ezra stuck through the morning and plowed through the afternoon.
By late afternoon, Halvork approached the base of the furnace, holding a long, heavy iron rod. His face and arms were shielded by thick, leather aprons and gauntlets.
"Slag is sitting high!" Halvork shouted over the noise, looking at the glowing seams around the clay plug.
He thrust the heavy rod directly into the upper section of the baked clay seal. He twisted his shoulders, driving his weight into the bar. The baked earth shattered inward.
A glowing, viscous stream of liquid poured out of the upper hole. This was the slag—the melted rock and impurities. It flowed like thick syrup, sliding down the dirt channel and pooling each into a pit. It hissed as it met the cooler air.
Halvork watched the flow carefully. At first, it was thick, but as it drained, the liquid became smoother, running clear.
"Slag is clear!" Halvork yelled, stepping back and tossing his iron rod to the dirt.
Arran stepped forward. He stripped off his leather gloves, preferring the bare hands he had been accustomed to. He picked up a fresh, thicker iron rod and aimed for the bottom of the hearth.
He drove the metal forward with a grunt, smashing the rod into the lower taphole. He hit it once, twice, three times.
The main seal broke.
A blinding river of molten iron erupted from the hole.
It was a staggering sight. It flowed fast, glowing into white. Without mana for reinforcement, the light singed the eyes and hurt the ones looking at it. The liquid metal surged down the main sand trench, filling the cavity, before branching off seamlessly to fill the dozens of smaller rectangular molds waiting in the sandbed.
Ezra's eyes flicked to the numbers in his vision. AMP registered the exact output: 1,480 degrees Celsius. The heat was staggering. The ambient air sent showers of sparks above the casting bed.
Ezra wanted to make sure that for the first firing everything was just right. He didn't want to admit it to himself but he was nervous. This was a make or break even for him. If this worked successfully it would justify more expenditures that Ezra had planned for in the future. He took a deep breath.
The stream began to thin and slow in to a trickle. Sparks flew from the open tap-hole just as the hearth had emptied.
"Plug it!" Halvork shouted over the roar of the waterwheel. "Plug it! Seal it! Seal the hole! Keep the heat in!"
A laborer stepped forward holding a ten-foot iron pole. There was a mass of dark, wet fire-clay the size of a man's head.
The laborer braced himself, aimed the pole, and drove it forward. He rammed the wet clay directly into the spitting taphole.
The furnace hissed. Steam and smoke broke outward as the heat baked the surface of the clay. The laborer leaned his weight into the pole for a few seconds, holding the plug tight, then twisted the iron shaft and pulled it back.
The clay stayed in the wall. The hole was sealed. The furnace roared on, trapping the air and allowing the next batch of iron to pool and separate.
Arran stepped back, slowly lowering his heavy rod. He let the sweat roll down his eyes like the first time he had forged a sword. He just stared silently at the glowing, bubbling ingots.
He was a master of his craft. He had spent decades of his life standing in front of a forge, pumping a hand-bellows, heating blocks of bloomery iron, and striking them with a hammer thousands upon thousands of times just to squeeze the impurities out of a single sword blade.
Now, in a matter of seconds, this monstrous kiln had produced more usable, liquid metal than his entire guild could yield in a month of labor. And it hadn't required a single drop of magic. It only required the river, the stone, and the right proportions.
Arran stared at the glowing iron. For decades, his trade had been bound by the strict rules of the smithing guilds. They passed down the exact dimensions of a bloomery and the exact swings of a hammer. It was a stagnant dogma. Innovation was discouraged. But looking at the sheer volume of metal pooling in the sand, Arran understood the shift. The old limits of his craft were gone. A new, sharp focus took its place.
Arran looked up at the towering blast furnace, then slowly turned his head to look at the small boy standing quietly on the perimeter of the yard.
Ezra watched the liquid fire settle into the casting sand. He remained completely quiet, his expression unreadable.
But in his mind he was ecstatic, this was the first step before mass producing steel. Right now iron would flow. He just needed to make the money back from the Iron Bren would produce.
Arran looked at Ezra. "According to the notes that Master Faraday had said. The Furnace cannot be turned off."
Ezra nodded.
Arran furrowed his brows. "So we need to do it in shifts?"
"Aye," The kilnmaster said as he smiled. "Like soldiers taking turns to stand watch."
Ezra glanced into the burning liquid and sighed. "Yes, the slag must flow."