The Gongdan and the Hwaryeok Military Academy (8)
Yi Yeon could not help but worry about Yi I's health.
He was only just past thirty, strong and hale, but he could easily overdo it.
So he asked.
“Are you getting enough sleep?”
But Yi I only smiled as if it were nothing.
“I sleep aboard the ships I sail back and forth on, Your Majesty. You need not worry.”
“What if you collapse on the way?”
“Your Majesty’s medicine is keeping me steady.”
‘Damn it!’
Yi Yeon had been sending Yi I ginseng and dried chicken meat—his own recipe—along with special tonics whenever he could.
Yet he still couldn’t rest easy, so he checked on him every time they met.
And every time Yi I gave the same answer.
Completely ignoring the worries of a king.
“Still, you must get enough sleep. If anything happens, who will build the steam engine?”
“I will try, Your Majesty.”
The moment the words “steam engine” left his mouth, Yi I’s face grew serious.
“Speaking of which, how far along are you with the extrusion process?”
“You said that once we put pig iron into the steel furnace, add powdered limestone and scheelite, and blow hot air underneath, we can obtain an alloy steel with excellent wear and heat resistance. So I have been waiting for the steel furnace to be completed.”
“Really?”
The main component of scheelite, which was easy to find in Gangwon-do or Jeonra-do without much trouble, was calcium tungstate (CaWO₄).
Yi I had not forgotten what the king had said.
“Yes, Your Majesty. And because it must be pressed with great force, we also need a steam engine. Therefore, once the steel furnace and the steam engine are finished, we can begin production immediately.”
“Impressive.”
“It is thanks to Your Majesty’s guidance.”
Yi I folded both hands over his belly and bowed respectfully.
Like a disciple to his master.
“Heh.”
Yi Yeon coughed awkwardly.
‘How could I possibly be his master…’
“Let me see it for myself.”
But Yi I said something else.
“Your Majesty, there is something else you should see first.”
“What is it?”
“It is a method that Captain Kim developed for making porous-cannon barrels with a revolutionary technique.”
“What did you say?”
Seeing the king’s surprised face, Yi I looked at Kim Ji and shouted loudly.
“Captain Kim! What is it? Hurry and show it!”
“Yes! Yes!”
Kim Ji clasped both hands respectfully and pointed to one side.
“Your Majesty, there is a new porous-cannon production factory built on the other side.”
At the end of the track made by joining two rows of steel pipes produced on a rotating line like train rails stood a signpost with the words “No Entry for Non-Authorized Personnel” in bright red letters.
Inside, ten or so steel rods hung from equipment arranged at regular intervals.
The steel-pipe track extended right up to the front of those machines.
‘What is this?’
At first glance it looked like a drill press.
But instead of the solid steel rods, nothing else was attached.
Below was a hole slightly larger than the steel rods.
Kim Ji walked up to the nearest machine and began to speak proudly.
“Your Majesty, the steel pipes produced from the rotating line are much stronger and more solid when made like this.”
“What does that mean?”
Seeing Yi Yeon’s puzzled expression, Kim Ji continued explaining quickly.
After listening for a while, Yi Yeon nodded and asked, “So you coat the steel rods with a mold made from aged soil, pour molten metal into the hole, and press it down like a mortar and pestle?”
“That is correct, Your Majesty.”
“You copied the process used to make cartridge casings?”
“Yes, Your Majesty. The steel pipes made this way are also very easy to finish.”
“Truly impressive.”
“Forgive me, Your Majesty.”
The equipment for making porous-cannon barrels that exploited the difference in melting points between nodular cast iron and steel rods was ingenious.
‘What should I call this?’
It was different from the cartridge-casing process, but pouring molten metal onto the steel rod coated with the mold was nothing like a hot-forging machine.
Yet it had produced steel pipes with the characteristics of hot forging.
‘Truly remarkable people.’
Yi I was a genius everyone knew, but Captain Kim Ji—who had created the victorious-cannon—had not been an easy person either.
“By the way, up to what length can you make them?”
The firmly hanging steel rods looked short.
“Maximum eighty centimeters is possible, Your Majesty. But if it exceeds seventy centimeters, the end becomes problematic, so we are safely producing at fifty centimeters.”
They would be inserted into a lathe connected to a windmill and finished with a whetstone.
Even if the steel rod was firmly fixed, it could sway slightly, so it was not uniform, but not a single one had ever broken or torn.
‘Of course.’
The characteristics of hot forging made the internal metal structure dense and increased fatigue strength.
“How much do they weigh?”
“The front end is 710 grams, the rear end is 410 grams, and the wooden handle is 80 grams—about 1,200 grams in total.”
“1,200 grams?”
Heavier than expected.
Nodular cast iron was lighter than steel, so he had thought it would be under one kilogram.
“Yes, Your Majesty.”
“How thick?”
“About three millimeters. If it is thinner, even after finishing, we cannot make it uniform.”
“Hmm…”
Three millimeters seemed to be the minimum gap the molten metal would need to escape when squeezed against the steel rod.
Still, it was slightly thicker than the 2.5 millimeters of the maximum barrel thickness of a Remington 870 or Mossberg 500, which was acceptable.
Since the porous cannon was pulled by holding the barrel, weight had been a concern, but this seemed just right.
‘Then I can move on to the next thing.’
Yi Yeon folded his arms and fell into thought.
‘With this, I can make sniper rifles.’
Since Yi I was always thirsty for new knowledge, he had not told him anything except when asked.
But there had to be a rifle capable of outranging an arrow.
So that the enemy commander could be taken out first.
Yi Yeon had already thought of one.
A simple sniper rifle that could load a bullet while fixed in place and used only a leaf spring.
‘The rolling-block action will do just fine.’
He had also decided to begin developing revolvers immediately.
Seeing Yi I’s expression, it seemed the steam engine would be finished soon, and the Bessemer furnace, which would be called the “Yi I Furnace,” was being produced without major problems.
‘Then steel will come flooding in.’
Moreover, since copper and iron were already piling up from trade with the Ming and Japanese, long cartridge casings could now be mass-produced.
* * *
—The Heunginjimun is the only gate among Hanyang’s gates that is fortified with a bastion. Please explain the reason.
“Aigoo…”
On the vast training ground, the candidates who had just taken the entrance exam to the Hwaryeok Military Academy sighed after reading the question.
It had clearly said that knowing only the first steps of Korean and mathematics was enough.
So they had studied the two books diligently, solved the example problems, and memorized everything.
But the only question that came up required them to write a full essay.
Many candidates were holding onto the pencils they had been given but could not write a single word.
However, some were still writing their answers with all their might.
Among them was Yi Sun-sin, who had come up from Bosung in Jeonra-do.
‘The Heunginjimun located downstream from Cheonggyecheon has a low elevation and is surrounded by flat land, making it vulnerable to attack. Therefore, they added a U-shaped barbican outside the gate to increase its defensive capabilities.’
After writing his answer, Yi Sun-sin turned to the next question.
It was about naval battles.
—In front of Okpo in Geoje-hyeon, the bay is a wide waterway about four kilometers (ten ri) long. Please write a tactic you can use when facing enemy ships here and explain the reason.
When a naval-battle question he had not expected appeared, some candidates grew angry and threw away their pencils and left.
Unlike them, Yi Sun-sin recalled his childhood war games and wrote his answer.
‘If a naval battle is to be fought in a wide waterway, we must first lure the enemy ships to cluster together. That way it will be easy to form the “hakikjin” formation. By pretending to flee in a straight line, then spreading out to the left and right and turning to concentrate fire on the clustered enemy ships, we can defeat them very effectively.’
“Oof…”
After finishing, Yi Sun-sin grabbed his painful shoulder and groaned.
The practical exam in the morning had tested stamina and endurance more than martial or artistic skills.
Carrying a sandbag weighing over thirty gyeong for nearly thirty ri on a mountain road and back.
But the chubby madman had run down the mountain path like crazy, tripped, and fallen.
As a result, the ones ahead had all been hurt.
He had been one of them.
‘It was Won Ja, the eldest grandson of the Won clan.’
The sound of him crying and screaming that his leg was broken still sounded like a pig’s squeal.
He had not even apologized to the injured people; instead, he had yelled at the proctors who had come running after hearing the news.
‘What kind of idiot are you? Aren’t you ashamed?’
He had performed such a foolish act and then boasted about his family. It was completely incomprehensible.
Yi Sun-sin shook his head and pointed to the next question.
It was to calculate the maximum range of a cannon according to its elevation and depression.
Next came the well-known question about facing cavalry with a porous cannon.
‘A method to effectively deal with charging cavalry…?’
Yi Sun-sin recalled the tactic he had used in his childhood mock battles and wrote his answer.
* * *
In the late Goryeo period, the Cheollyeongwei was established by the Ming as one of their military exercises to resolve disputes between the factions surrounding the Liaodong region.
Now it had become the Ming’s forward base, controlling and gathering information through trade with the Jurchens.
There, Kim Seong-il vented his dissatisfaction to Hwang Yun-gil.
“How is it that those bastards are ignoring us like this?”
“If you are the total general of Liaodong, then it makes sense. So you should just endure it.”
“I cannot endure it. Aren’t those people traitors who betrayed their country and swore loyalty to the barbarian tribes?”
“Huh! How can you say such a thing? What if someone hears it?”
“I said it. Did I say something wrong?”
“It is wrong. Isn’t that the right thing to say?”
“What is wrong about it? Everyone knows I am from the governor of Gyeongsang Province.”
“Aigoo…”
Hwang Yun-gil sighed deeply.
He had come to meet Li Chengliang, the total general of Liaodong, on the king’s special order.
He wanted to persuade him somehow to stop interfering with coal mining in Musun.
But three days had already passed since the request for the meeting, and there was still no news.
Enraged, Kim Seong-il began to curse without restraint.
He wondered if it would reach the general’s ears.
“Why are you sighing like that?”
“Is performing His Majesty’s order more important, or is calming your own feelings more urgent?”
“That…”
Kim Seong-il stopped mid-sentence and clicked his tongue.
He felt he had spoken too carelessly even in his own mind.
“It is too much, isn’t it? The Emperor would not do such a thing.”
“Because it is not the Emperor. And there must be something he is thinking. Didn’t we not return the gifts we gave him?”
“What do you mean?”
“You know as well as I do. Aren’t they all people who fled here after being persecuted in Joseon?”
“What does that have to do with it?”
“Ugh…”
Hwang Yun-gil sighed again.
He had never imagined how difficult it would be when the king had assigned him as his companion.
He had thought a newly appointed official would obey without question, but every single matter was a complaint.
It turned out that his teacher, Yi Hwang, had been expelled by the king without reason.
‘How could he send someone like that?’
He had no choice but to come secretly because he had to keep an eye on the Ming’s gaze.
Yet sending someone who acted impulsively despite trusting the family’s prestige did not match the king’s reputation for having excellent wisdom.
Still, he had to appease him and complete his mission.
That was the duty of a scholar who had studied Seongrihak.
“You should not be like this. You seem sharpened by the journey here—take some rest.”
“It is fine. I have had plenty of rest while waiting.”
“Then shall we drink some tea? There is a good tea here.”
“Why don’t we have a drink of alcohol instead?”
“That is out of the question.”
“Why?”
“Heh, really!”
He was completely at a loss for words.
“Lord!”
A voice came from outside.
“Are you in?”
“What is the matter?”
He opened the door and entered, smiling broadly.
“The total general said he would come here tonight.”
* * *