The Imperial foundries in Solstice were a cathedral of ancient techniques and staggering inefficiency. While Oakhaven's workshops were organized around the flow of material and the logic of the "Deep-Pulse," the Imperial works were a labyrinth of hereditary guilds, each guarding their secrets with a religious fervor that stifled progress. Deacon's "consultants"—a hand-picked team of five engineers led by Miller—were treated like lepers in silk coats, allowed into the inner sanctum only by the direct command of the Emperor.
"They're using sand-casting for the high-pressure cylinders," Miller whispered to Deacon as they stood on the observation catwalk. Below them, a hundred men struggled to pour molten iron into a crude earthen mold. "The cooling rates are all over the place. Half of these blocks will have internal fractures before they even see a drop of steam. The Sovereign isn't a locomotive; it's a bomb waiting for a fuse."
Deacon watched the chaotic scene below. The Lord High Steward wanted the formula for the "Oakhaven Alloy," the heat-resistant steel that allowed for thinner, more efficient boiler tubes. To give it to them purely would be to surrender the North's only leverage.
"We aren't going to fix their casting," Deacon said, his voice barely audible over the roar of the furnaces. "We're going to give them exactly what they asked for—the alloy. But we're going to 'optimize' the boiler design for the Sovereign in a way that requires a specific, high-frequency maintenance schedule."
The plan was a masterclass in Planned Obsolescence. Deacon sat with the Imperial Board of Works engineers for three days, sketching out the new boiler layout. He introduced a "Superior Heat Exchange" system that utilized thinner, more conductant tubes made of the Oakhaven Alloy. On paper, it was a miracle of efficiency, promising twice the speed of the Pathfinder.
In reality, Deacon had designed the thermal expansion rates of the tubes to be slightly out of phase with the Imperial-grade iron of the boiler shell. At low speeds, the engine would perform flawlessly. But at the high pressures required for express travel, the constant heating and cooling would cause the "Creep" of the metal to stress the rivets.
"The alloy requires a 'Catalytic Wash' every thousand miles to prevent scaling," Deacon explained to Chief Engineer Sterling, handing him a sealed flask of a blue-tinted chemical solution. "Without this specific Oakhaven distillate, the tubes will become brittle and crack under the vibration of the standard gauge."
"You're making us dependent on your chemicals," Sterling said, his eyes narrowing as he examined the flask.
"I'm making the Sovereign a precision instrument," Deacon countered. "If you want a machine that runs on coal-dust and prayers, build a mule-cart. If you want the fastest rail-line in the world, you follow the Oakhaven Standard."
The "gritty" work of the consultancy began in the casting pits. Miller and his men oversaw the "Alloy Infusion," a process that required precise timing. The Imperial smiths, resentful of the Northern oversight, attempted to sabotage the pours by "accidentally" introducing impurities. Miller caught a master smith trying to toss a handful of copper-slugs into the vat—an act that would have made the steel too soft for high-pressure use.
"You do that again, and I'll have the Steward put your head in the mold for the next pour," Miller growled, pinning the smith's hand to the workbench.
The tension in the foundries was a physical weight. The Oakhaven team slept in shifts, guarding the alloy vats with their lives. They were in the heart of the enemy's power, building a weapon that would eventually be turned against them.
As the first set of tubes for the Sovereign was successfully cast and fitted, the Lord High Steward returned to the floor. He watched the blue-tinted "Catalytic Wash" being fed into the system, fascinated by the way it seemed to coat the metal in a protective sheen.
"It works," the Steward noted, watching the pressure gauge climb on the test-rig. "The Sovereign will be ready for its inaugural run to the Eastern Front by mid-summer. You've done your duty, Lord Cassian."
"The alloy is only half the battle, Steward," Deacon said, wiping a smudge of soot from his sleeve. "A machine this complex requires an Oakhaven-trained 'Master of the Watch' to oversee the maintenance. I suggest you send your best engineers to our valley for a six-month 'Acclimatization' program."
The Steward smiled, a cold, thin expression. "I think we've had enough Northern 'acclimatization' for one season. We have the formula, and we have the design. You are free to return to your mountains."
As Deacon and his team boarded the ship back to the North, Miller looked back at the smoke-stacks of Solstice. "You think they'll figure it out? The expansion-lag in the tubes?"
"Not until they push the engine to full throttle on a winter night," Deacon said. "By the time the Sovereign starts blowing its seals, we'll have the only factory in the Empire capable of producing the replacement parts. We didn't give them a locomotive, Miller. We gave them a subscription to Oakhaven's mercy."
The "Shadow-Rail" was a threat, but it was now a tether. Deacon had tied the Empire's most prestigious project to the Northern foundries. He had won a season of peace, but he knew the moment the first Sovereign failed, the Steward would come for him—not with a request, but with an army.