The Great Song Dynasty's Soul-Forging in Progress

In Lüjiachang, the frost wind was like a knife, and snowflakes were flying everywhere.

The newly built workshop is situated in a sheltered spot at the mouth of the bay. The rammed earth walls are covered with white frost, but inside is a completely different scene—three earthen blast furnaces burn day and night, casting distorted and wild shadows of people onto the walls. The air is filled with the smells of charcoal, sweat, and burnt hair, all mixed together to create a unique, oppressive heat that belongs to the workshop.

Qin Tiehua, who has fully recovered, has not been home for seven days.

The blue cloth ribbon that had originally bound her hair was now charred black by the sparks, and was simply tied with a hemp rope, her wet strands clinging to her forehead. Her thin cheeks were reddened by the fire and covered in soot, making her look like a painted face on a theatrical stage. Yet her hammer swings were perfectly steady, each strike sending sparks flying from the anvil and making her arm go numb.

"Splash—"

Another iron billet cracked in the cold water, breaking into seven or eight pieces. This was the third failure of the day.

"Damn it!" Old blacksmith Huang Daniu slammed his hammer on the open ground. "We've added graphite powder, and modified the blower three times, but it still doesn't work! If this keeps up, all the stock in our Lüjiachang will go to waste!"

The young apprentices exchanged bewildered glances, one of them muttering under his breath, "This method is probably just not going to work..."

"Who said that?" Qin Tiehua whirled around, his phoenix eyes wide and his gaze sharp as lightning. "Uncle Da Niu, what did you say when you taught me blacksmithing? — 'If the fire isn't strong enough, don't blame the iron for being disobedient.' Now that the fire isn't hot enough, we should find a way to make it burn brighter, instead of just pounding the hammer here!"

Her voice was hoarse, yet every word was sharp and clear. Huang Daniu's face flushed red, and he stubbornly tried to retort, but he saw Qin Tiehua already bending down to pick up the broken pieces of iron and examining them carefully against the furnace fire. Her fingers were sizzling from the heat, but she seemed completely oblivious.

Wang Zhonghua remained squatting by the furnace, drawing something on the ground with a charred twig. He already knew the problem—modern steelmaking required coke, regenerators, and precise temperature control. But what use was knowing the general direction? He couldn't even figure out how to tighten the leather of the bellows to prevent leaks. All the knowledge he had from Baidu Encyclopedia in his previous life seemed like a joke in front of this makeshift blast furnace.

"Iron painting," he began, his voice hoarse from the smoke, "I'm wondering if this furnace is cooling down too quickly?"

"Hmm." Qin Tiehua didn't look up. "The furnace walls are too thin; the heat can't be retained."

"Then... what if we use refractory mortar to line it with a layer? And then build a reflective arch inside to concentrate the firepower in the center." Wang Zhonghua drew a crooked arc with a twig. "And this bellows, the single-pipe air push is too slow, so we'll change it to a double-action type, so that both pushing and pulling can deliver air, doubling the air volume."

"A double-acting bellows?" Qin Tiedan scratched his head. "What is that? I've never heard of it."

"Well..." Wang Zhonghua gestured for a long time, but he couldn't explain how the piston structure could be implemented.

Just as they were struggling with this problem, a thin young man stood up from the corner of the workshop, brushing the dust off his knees. He wore a faded blue cotton robe, the sleeves rolled up high, revealing a section of his slender forearm. He wore two crystal "glasses"—specially made for him by Wang Zhonghua; though rough, they allowed him to see things up close. At that moment, the lenses were covered in coal dust, but he seemed oblivious, staring intently at the distorted pattern on the ground, his eyes growing brighter and brighter.

"Young master, this painting..." the young man began, his voice still slightly hoarse from puberty, yet unable to suppress his excitement, "Wonderful! Absolutely wonderful!"

It was Shen Kuo.

He crouched down, picked up the twig Wang Zhonghua had discarded, and began to draw again on the ground, explaining as he drew: "Please look, gentlemen, the wonder of the double-action bellows that you mentioned lies in these two words, 'leaving valves.' Ordinary bellows, when pulled, take in air, and when pushed, take out air, only working for half the time. If you add a partition inside the bellows, with valves at both the front and back—" He drew quickly, the lines, though childish, were extremely clear, "When pushed, the front valve closes and the back valve opens, so air comes out from the back; when pulled, the back valve closes and the front valve opens, so air comes out from the front. In this way, with each push and pull, air is sent into the furnace, doubling the air volume!"

Qin Tiehua squatted down beside him, stared at the drawing for a long time, and suddenly slapped Shen Kuo on the shoulder: "Good lad! How did you figure that out?"

Shen Kuo stumbled from the slap, adjusted his glasses which had almost fallen off, and said with a flushed face, "No... it wasn't my idea, it was the young master's drawing. I just... just explained it more clearly."

"Explaining it clearly is no easy feat!" Qin Tiehua's eyes gleamed. "I looked at it for ages and felt it could work, but I couldn't explain how. Now that you've explained it, everything is clear: how to install the trapdoor, how to set up the partitions!"

Shen Kuo rubbed his hands sheepishly, then pointed to the furnace and said, "And this vaulted ceiling, the young master drew an arc shape. If it were built with wedge-shaped bricks that interlock, it would be much more stable than a flat roof and would retain heat better. I... I've been reading the 'Kao Gong Ji' these past few days, and there's a method for 'round tiles' in it, which we can learn from."

Looking at this future scientific giant, Wang Zhonghua felt an indescribable surge of emotion. These past few days, he had kept Shen Kuo by his side, having him learn blacksmithing from Qin Tiehua, identify medicinal herbs from Liu Jueming, and study classical texts with the old scholar. This lad was like a thoroughly dried sponge, absorbing everything he saw, digesting it, and applying it to new situations. Now, he could even combine the ancient methods in the *Kaogongji* (Record of Trades) with his own sketches; his comprehension was simply terrifying.

"Cunzhong," he called Shen Kuo by his courtesy name, "how do you think it's possible to build this vaulted ceiling securely using wedge-shaped bricks?"

Shen Kuo adjusted his glasses, squatted down, and continued drawing: "Young master, you can first use a wooden mold as a base, then lay bricks from both sides towards the middle, and finally wed in a specially made 'locking brick' at the top center. In this way, the entire vault will be interlocked as one, and it will not collapse even if the wooden mold is removed. I saw that the dome of Doctor Liu's medicine hut was built in this way. I asked the bricklayers, and they said it is called 'issuing vouchers'."

Qin Tiehua listened intently, then suddenly slapped his thigh: "I remember now! When I was little, I helped my father build a stone bridge, and the arch was built just like that! That's right, the arch can bear a thousand pounds, so why can't the furnace roof retain heat? Cunzhong, you really are a treasure!"

Shen Kuo blushed deeply from the praise and stood there speechless, at a loss for words.

Wang Zhonghua patted him on the shoulder with a smile: "Don't just be happy, there's still work to do. I have an idea for iron painting—we need to record the details of each batch during this trial firing: when the fire was lit, how much charcoal was added, how much graphite powder was added, how many times the bellows were pushed and pulled, what color the furnace fire was, what the color of the molten iron was... record it all. Cunzhong, I'll leave this to you. You have good handwriting and are meticulous."

Shen Kuo's eyes lit up, and he nodded vigorously: "Don't worry, young master, I'll go get paper and pen right away!"

Qin Tiehua was somewhat puzzled: "Why bother memorizing all this? Blacksmiths rely on feel and eyesight; what's the use of memorizing it?"

"Feel and eye can be forgotten, and it varies from person to person," Wang Zhonghua said earnestly. "Write it down, and it becomes a rule. No matter who is in charge of the furnace in the future, as long as they follow these rules, they can produce good steel. This is called turning experience into knowledge."

"Turning experience into knowledge..." Qin Tiehua pondered these words, his gaze towards Shen Kuo now filled with even more fervor. "Cunzhong, you'd better remember this well. From now on, what you write will be the family heirloom of our Lüjia Village, no, our Sanyi Village!"

Shen Kuo nodded heavily, turned and ran outside, but after a few steps he turned back, carefully pinched the pattern on the ground with his fingernail to make marks, and then ran out to get paper and pen.

In the days that followed, the entire Lüjiachang seemed to be under a spell.

The refractory clay had to be repeatedly pounded to remove all the sand particles until it could be drawn into long threads. Qin Tiehua, along with several women, walked barefoot in the mud piles from morning till night, until her ankles swelled up like radishes. She didn't complain of the pain, but gritted her teeth, sweat mixed with mud dripping down her face, soaking into the mud with each step she took.

Modifying the bellows was even more arduous. If the cowhide wasn't tightly sealed, it would leak air; if the wooden planks weren't joined securely, they would crack. Qin Tiehua didn't sleep for three days and three nights, his eyes bloodshot from exhaustion. He personally sewed seven layers of cowhide with hemp thread and then applied a paste made of tung oil and lime to the seams.

Wang Zhonghua wanted to help, but she pushed him away—"Your fingers are delicate, don't prick them. I'm good at this."

Shen Kuo, like a little shadow, followed Qin Tiehua around every day, holding a notebook made of birch bark, which he filled with charcoal notes:

"On the ninth day of the tenth month, at the third quarter of the morning, the pounding of refractory clay began. The clay was taken from three miles east of Lüjiachang; it was bluish in color and sticky in texture. After pounding it eight hundred times, it could be pulled into an inch-long thread. Sister Tiehua said that it was better when it 'sparkled with oil'."

"On October 11th at noon, the bellows partition was installed and tested, but it leaked air. Sister Tiehua disassembled it and re-sewed it, applying tung oil and lime paste to the seams. After testing again, it did not leak."

"On the thirteenth day of the tenth month, at the hour of Xu (7-9 PM), the arch of the new furnace was joined together. Cunzhong, following the method of 'round tiles' in the Kaogongji (Record of Trades), discussed with the bricklayers the use of wedge-shaped bricks to create the arch. When the last locking brick was driven in, everyone held their breath. Fortunately, it did not collapse."

Every stroke was neat and tidy, with occasional rudimentary diagrams. Wang Zhonghua glanced through it once and nodded inwardly—this kid's observation and recording abilities were simply innate talents.

At dawn on the fourth day, when the first rooster crowed, the new furnace was finally erected.

The inner wall of the furnace was lined with three inches of refractory mud, and the dome-shaped ceiling held the flames in place. The double-acting bellows pushed and pulled, emitting a "whoosh whoosh" sound, like a beast that had just woken up.

"Ignite it!" Qin Tiehua gave the order.

With trembling hands, Huang Daniu fed the embers into the furnace. At first, the flames weakly licked the graphite. But as the bellows rhythmically pushed and pulled, the flames began to swirl and rise, their color changing from red to yellow, from yellow to blue, and finally bursting into a blazing white!

"Retreat! Retreat quickly!" someone exclaimed.