The Thermal Flare had successfully shattered the Imperial perimeter, but it had also revealed the fragility of Kael's energy ledger. The basalt accumulators were cooling, and with the surface blocked, the peat shipments were non-existent. To maintain the heat, air, and pressure required to keep 595 souls alive underground, Kael could no longer rely on stored energy. He had to tap into the source. Beneath the limestone strata of Outpost Alpha lay the dormant volcanic veins that gave the Salt-Spurs their name. He initiated the Geothermal Bore.
The grit of the project was the transition from horizontal mining to vertical penetration. Kael needed to drill a four-inch shaft five hundred feet straight down into the crust. To do this, he designed the Diamond-Tooth Rotary Bit. Lacking actual diamonds, he used industrial-grade black garnets and high-carbon steel "shards" embedded into a cast-iron head.
The technical heart of the bore was the Segmented Drill-String. Kael utilized ten-foot lengths of thick-walled iron pipe, threaded at each end. As the drill went deeper, new segments were added. To turn the bit at such depths, he redirected the primary steam piston to a massive horizontal flywheel, which used a leather belt-drive to spin the vertical drill-string.
"We aren't just cutting stone, Hektor," Kael said, his voice straining against the rhythmic clack-clack-clack of the flywheel. "We're fighting friction. If the bit gets too hot, it will weld itself to the bedrock five hundred feet down, and we'll lose the hole."
To prevent this, Kael implemented a Constant-Flushing System. He used the high-pressure water from the aqueduct to pump a thick mixture of clay and pulverized stone—"drilling mud"—down the center of the hollow pipes. This mud cooled the bit and carried the rock cuttings back up to the surface between the pipe and the borehole wall.
Socially, the Geothermal Bore became a focal point of hope and anxiety. The "Mirror-Readers" in the command vault reported that Arch-Magister Vane was bringing up heavy wagons of seasoned timber—likely building permanent barracks to outlast the winter. The citizens knew that if the bore failed, the mountain would eventually go cold. The Tier 0 laborers worked in absolute synchronization, their movements dictated by the "Drill-Song"—a rhythmic chant used to time the addition of new pipe segments.
A technical failure occurred at the three-hundred-foot mark. The drill-string hit a pocket of high-pressure ancient steam—a "micro-vent." The sudden pressure reversal blew the drilling mud back out of the hole like a geyser, showering the crew in boiling silt and nearly snapping the iron pipes.
Kael didn't retreat. He utilized the Blowout Preventer—a heavy iron "gate valve" he had designed for exactly this scenario. He and Drax fought through the scalding spray to crank the valve shut, sealing the pressure within the earth.
"We've hit the heat early," Drax grunted, his arms red from the steam. "Do we stop?"
"No," Kael replied, his eyes on the pressure gauge. "We harvest it. We don't need to go five hundred feet if the vent is here. We're going to case this hole and turn it into a Subterranean Boiler."
The first Clean Steam was drawn from the bore. Kael opened the secondary valve, and a steady, high-pressure jet of natural volcanic steam hissed into the accumulator tanks. It was a victory of pure geology. The barony finally had an infinite, self-sustaining pulse.
Kael stood by the trembling pipe, the heat radiating through the stone floor. He had secured the mountain's survival. But as he looked at the population logs, he realized the ultimate limit of the Vaulted Outpost wasn't energy or stone—it was the biological ceiling of 595 people.
The mountain is alive, Elms, Kael said, feeling the vibration of the volcanic steam. We have the power now. But as long as Vane is up there, we are a closed circuit. Once we break this blockade, we can't just go back to being a barony. We need to become a city. We need thousands, not hundreds. We need to outgrow the Empire's ability to count us.
Kael looked at the blueprints for the next eighty tiers of expansion. "The bore is just the start. We aren't just digging a hole; we're digging the foundation for an empire of our own."