Chapter 23: Calculating the Mine's Profits

Landlord Zhang’s household was in an uproar, but Lin Chuan was naturally oblivious to it all.

At this moment, he was squatting before the blacksmith’s forge, his eyes fixed on the surging tongues of fire within the earthen furnace. Waves of heat, carrying a pungent scent of sulfur, washed over him. Two auxiliary soldiers, stripped to the waist, worked the bellows. With every pull, the charcoal inside the furnace erupted in a shower of sparks.

"Squad Leader, the quality of this batch of ore is better than expected," said Blacksmith Zhao, lifting a piece of ore with iron tongs and tapping it. "Judging by the sound, the iron content must be around forty or fifty percent."

Lin Chuan nodded, picked up a piece of charcoal, and began calculating on the ground. When he was in the mine, he had carefully tallied the excavation status.

"The mine can accommodate twenty strong laborers, producing eighty loads of ore a day. But after screening for usable material, I’m afraid only sixty percent remains. Using the old smelting method, ten catties of ore yield three to four catties of iron."

Blacksmith Zhao turned to look at the mountain of ore. "But we only have three bellows. By my count, we can only fire six furnaces a day."

"Six furnaces?" Lin Chuan calculated rapidly. "If each furnace yields twenty-five catties, that’s one hundred and fifty catties of iron a day."

Blacksmith Zhao grinned, revealing a toothless gum. "The Squad Leader is truly a scholar; you can calculate that without an abacus?"

Lin Chuan smiled and drew a few more lines on the ground. "Subtracting twenty percent for loss, that’s about four thousand catties of pig iron a month. Pig iron sells for sixty wen per catty..." He paused for a moment before continuing, "Four thousand catties means two hundred and forty taels of silver!"

Hu Dayong, who had been staring at the "ghost symbols" Lin Chuan was drawing, was stunned by the figure. "Two hundred and forty taels? That’s more than our monthly military pay!"

"But we have to deduct the costs." Lin Chuan began sketching out a formula. "For the twenty brothers mining, each gets eight qian of silver a month; for the five transporting the ore, six qian each. Plus the charcoal and materials for the forge..." He calculated quickly. "The daily expense is one tael and three qian, totaling forty taels a month."

Hu Dayong fiddled with his fingers, struggling to keep up with the math, but he understood the final result. "Two hundred taels! Squad Leader, can’t we just sell the pig iron instead of forging weapons?"

"No selling pig iron," Lin Chuan shook his head. "We’ll forge them all into arrowheads. One arrow sells for eighty wen at the garrison camp, and one catty of iron can make five arrows. Four thousand catties of iron will make twenty thousand arrows, which can sell for... one thousand six hundred taels!"

Hu Dayong gasped. "What?!"

"But we only have three blacksmiths," Lin Chuan said, calming down. "Uncle Zhao, how many can each person forge in a day?"

"Twenty for now. Once we’re skilled, maybe thirty."

"Hmm... two thousand a month, one hundred and sixty taels of silver..." Lin Chuan frowned. "Too slow. Uncle Zhao, can we recruit more blacksmiths?"

"Where would we find ready-made ones?" Blacksmith Zhao shook his head. "Blacksmithing takes time to master. Without the skill, they can't forge triangular arrowheads."

"Then what if you train apprentices? We'll pay extra!"

"Train apprentices?" When Blacksmith Zhao heard about the extra pay, his eyes lit up. "We can have the miners learn at night! I’ll train them; they should be proficient within three months."

"Good! That’s settled." Lin Chuan stood up. "Hu Dayong, starting tomorrow, the mine will work in three shifts: two for mining, one for learning to forge. Uncle Zhao, you oversee the smelting and forging—ensure the quality is top-notch."

As night deepened, the forge fire burned bright. The dancing flames cast Lin Chuan's shadow against the stone wall, flickering in and out of sight. He squatted by the pile of ore, using the firelight to recalculate the figures. The problem was that while raw materials were abundant, production capacity lagged behind. The daily output of ore was piling up. If the forge could expand to a dozen people and he could find ways to improve smelting efficiency, the profits from this mine alone could exceed two thousand taels.

As it stood, they were only netting a little over a hundred taels a month. This small sum was barely enough to feed a few dozen people. But that was not Lin Chuan’s goal, just as Tielin Fortress would never be his final destination. His mind held the technology of future generations: blast furnace iron smelting, hydraulic trip hammers, and gunpowder formulas that could shatter mountains. In these chaotic times, if he could utilize them properly, he would carve out a world of his own. How could he be satisfied with a mere hundred taels?

"Squad Leader, it’s time to rest." Hu Dayong brought over a coarse cloth cloak and draped it over his shoulders.

Lin Chuan shook his head and drew another circle on the ground. "I haven't finished calculating..."

The ground was already covered in dense symbols: straight counting rods, circled numbers, and crooked diagrams of arrows. Hu Dayong hesitated before sitting down beside him.

"Squad Leader, what are these drawings?" He pointed at the tadpole-like symbols. "I can't understand a single one."

"Mathematics," Lin Chuan said without looking up, drawing a diagonal line through a circle. "The Arab method; it’s faster than our counting rods."

"Arabs?" Hu Dayong scratched his head. He had never heard of such a place.

"They should be... in the west," Lin Chuan said casually. He wasn't sure if Arabs existed in this timeline.

"Are they those blue-eyed barbarians from the west? Can they use an abacus too?"

"It’s not an abacus; it’s numbers." Lin Chuan finally looked up and used the charcoal to write "123" on a blank space on the stone slab. "Look, this is one, two, three. It's much easier than drawing horizontal lines."

Hu Dayong stared at the string of symbols, his eyes gradually brightening. "Really! Three strokes for three numbers? What if you count to a hundred..."

"Just write a '1' followed by two '0's." Lin Chuan smiled and added two circles after the '3'. "See, that’s three hundred."

"Squad Leader! If we learn this, accounting will be ten times faster!" Hu Dayong exclaimed. "But this is a secret skill of the barbarians; how do you know it?"

Lin Chuan didn't answer. Instead, he pressed the charcoal into Hu Dayong’s palm. "Want to learn? I’ll teach you. From tomorrow, come to the forge at the third quarter of the Mao hour every day."

"Re-really?" Hu Dayong’s hand, holding the charcoal, trembled slightly. This was an incredible stroke of fortune. In this world, knowledge was mostly hoarded by noble families and kept secret from outsiders; some families even passed their knowledge to only one person per generation. Before following the General, he had been an apprentice at a grain store. When he tried to borrow a copy of the *Nine Chapters on the Mathematical Art*, the shopkeeper had cursed him, asking what a "mud-legged peasant" wanted with the books of sages. Now, Lin Chuan was offering to teach him personally!

That meant the Squad Leader... was his teacher.

"Squad Leader..." His throat tightened. Not knowing what to say, he clumsily cupped his hands in a salute.

Lin Chuan patted his shoulder, his gaze sweeping over the symbols on the ground before looking out into the distant night. The night breeze carried a scent of rust, but it felt more filled with ambition than usual.

"From now on, the accounts of Tielin Fortress must be kept clearly." He said, "Once you master the Arab arithmetic, I’ll teach you more."

"There's more?" Hu Dayong’s head buzzed.

"Of course!" Lin Chuan laughed. "The world is vast and knowledge is broad; how could arithmetic alone describe it? Once you are proficient in Arab arithmetic, I will teach you the arts of investigation: how to measure time with a copper water clock, how to use the principle of levers to improve trebuchets, and I will even teach you the basics of alchemy—to identify the nature of minerals and sulfur, and to refine the fierce oil that can burn down cities..."

He spoke with great enthusiasm, oblivious to the fact that in Hu Dayong’s eyes, the Squad Leader—no, Master Lin—was already glowing like a saint.

"I—I will definitely learn well!" Hu Dayong suddenly knelt and knocked his head against the ground twice.

Lin Chuan was startled and was about to ask what he was doing when he saw Hu Dayong stand up and turn to walk away. But he wasn't heading toward the barracks.

"Where are you going? Not going to sleep?" Lin Chuan called out.

"No more sleep, Master!" Hu Dayong replied in a muffled voice. "I’m going to train—"