Late Yuan Dynasty: I am the true emperor

Chapter 166: Gun Test (Part )

Everyone looked at Yang Huan's operation, the strange ruler inserted in the muzzle of the gun, and the conversation between the two people, and they all expressed their confusion.

Feng Guoyong immediately asked, "Marshal, what is this thing stuck in the muzzle? What is its function?"

"This thing is called a cannon gauge. The 'gauge' in 'rules' is a kind of ruler, specially used to measure the elevation angles of artillery." Seeing that everyone didn't quite understand, Lu Jin explained to them.

Xu Da was also curious, "What is the pitch angle? How does it relate to firing a cannon?"

This time, Lu Jin didn't explain again. Instead, he pointed to the side and said, "Yang Huan, you come and tell everyone."

"Yes." After Yang Huan arranged the artillery operation, he immediately came to the side to explain to everyone.

"The Marshal said in his lecture that the ultimate goal of firing cannonballs is to throw cannonballs at the heads of the enemy. This is essentially no different from throwing stones, just like archery, crossbows, and catapults. In fact, they are all just for throwing objects out. The objects thrown out are affected by gravity. Everything thrown out will eventually fall down. The trajectory of the object in the air is called a parabola by the Marshal.

"When we fire cannons, we actually throw iron balls. The parabola of the iron ball's flight has a special term in artillery called ballistics. Ballistics is divided into internal ballistics and external ballistics. This cannon gauge is used to measure the pitch of the gun barrel and calculate the trajectory.

"It's like archery. If a bow can only shoot a hundred steps when it is level, then if you lift the bow a little and shoot it higher, you can shoot a hundred and fifty steps, or even two hundred steps. The higher you lift it, the farther you can shoot. Of course, this is not accurate. The Marshal said that the longest range of a parabola should be a 45-degree elevation angle, which is called the longest parabola. If you lift it too high, more than 45 degrees, the range will become shorter.

"The kind of artillery we use is called a flat-fire artillery. When in use, the elevation angle generally does not exceed 15 degrees. The gun gauge is like the sight on a crossbow. Insert the gun gauge into the gun barrel and look at the angle between the plumb line and the gun gauge. If it is 89 degrees, it means that the artillery is in a horizontal state. If the angle is 1 degrees, it means that the current gun elevation angle is degree.

"Using the same charge and firing shells of the same weight, by adjusting the elevation angle, the shells can be fired at different distances. The Marshal also taught us a lot of mathematical algorithms, all of which are the science of calculating ballistics."

Everyone was stunned. They looked at each other. It turned out that there was so much knowledge involved in firing cannons. One had to learn arithmetic. No wonder the Marshal specially found a group of children to learn cannon tactics.

At this time, Xu Da frowned and thought for a while, then asked another question, "That is to say, as long as you know the distance between the enemy and the artillery, you can calculate how high the gun barrel should be raised to hit the enemy, right?"

"Yes." Yang Huan nodded affirmatively.

Upon hearing this, Xu Da immediately asked, "How do you know how far away the enemy is from us when you can't run to the enemy's front and measure with a ruler?"

Everyone nodded frequently when they heard this. This was indeed a very important issue.

Yang Huanze immediately explained, "The most important subject in artillery is distance measurement. Only when you can measure accurately and calculate quickly can you hit accurately. For distance measurement alone, the Marshal has taught three methods.

“If we are on the defensive in a predetermined battlefield, such as defending a city or a fortress, and the artillery position is a fixed artillery position, we can take advantage of the enemy’s arrival to measure and draw a good artillery map, so that when the enemy arrives, we can hit the target every time.

“If it is a field ambush, if conditions permit, we should also measure and draw maps in advance and make markings so that we can hit the target every time during the battle.

"If it is a field encounter and it is not possible to map in advance, the triangulation method, also known as the eye-jumping method, can be used to measure the approximate distance.

"There are also distance measuring instruments. The Marshal has a telescope with a position sensor for distance measurement. You can see the distance directly through the telescope, but this kind of instrument cannot be manufactured yet."

After Yang Huan finished speaking, he pointed to the monocular telescope next to him, which had already been set up and aimed in the direction of the shooting range.

The veterans present certainly knew about Lu Jin's telescope, but newcomers like Xu Da had never seen it. When they heard that this thing could also measure distance, they immediately became curious.

"How do I use this?"

Yang Huan didn't say anything when he heard this, but turned to look at Lu Jin, who then said, "Go and see whatever you want to see."

The three newcomers could no longer hold back, and under the guidance of Yang Huan, they all began to observe through telescopes. The target two miles away was clearly visible in the telescope. Guo Xing turned slightly and looked towards the direction of the city wall. He could even clearly see the soldiers standing guard on the top of the city wall. He couldn't help but gasp.

"Hiss, this thing is really a magical tool, a telescope, a telescope. With this thing, wouldn't it mean that any deployment of the enemy army cannot be hidden from our army? It is really a sharp weapon for spying on the enemy camp. Marshal, can't we make this thing ourselves?"

Lu Jin shook his head. "It can be made. If the world is peaceful, we can spend a few years to gather skilled craftsmen and make it. But in this world, we don't have the time to make this thing."

After Xu Da read it and heard what Lu Jin said, he couldn't help but sigh, "That's a pity. It would be great if this thing could be distributed to all scouts in the army. When attacking a city, we can also build a high tower outside the city and put this telescope on the top of the tower to see the real situation inside the city."

After that, he asked, "This telescope cannot be manufactured nowadays, so how can we measure distance in the field? What are the limitations of the eye-jumping method you mentioned?"

This time Yang Huan did not hesitate and said immediately, "The eye-jumping method does not require any equipment. All you need is hands, eyes, and arithmetic. Just like this, use your eyes to look at the target alternately, and then do mental calculations to get the approximate distance. If Officer Xu doesn't believe me, we can give it a try."

Seeing that he just stretched out his arm, raised a thumb, opened one eye and closed the other, Xu Da said that this could measure the distance. He was very curious and looked at Lu Jin.

Lu Jin nodded, "The shooting range is marked, you can just pick an unmarked place in the barracks."

Xu Da was delighted. He looked around and immediately saw the generals' platform. Lu Jin's central army banner was still standing there. He immediately said, "Let's go to the generals' platform."

As soon as these words were spoken, Yang Huan immediately raised his hand and began to estimate. Several idle soldiers in the artillery squad also began to raise their hands to measure the distance. When Lu Jin heard the target chosen by Xu Da, he could not help laughing.

The eye-jumping method is relatively accurate when there are clear markers. The most feared thing is the grassland, the sea, the sky. There is no such place as this, and it is impossible to measure. However, Xu Da chose the Dianjiangtai as his target, which was a free point for Yang Huan, because he knew the size of the flagpole. With a clear marker, it would not be difficult to measure the distance. Sure enough, in less than ten breaths, Yang Huan had measured the result, "From where I am standing, to the flagpole, it should be about 860 meters."

"Nine hundred meters, I think."

"Eight hundred and fifty meters."

The soldiers from other artillery squads also gave their answers.

Xu Da looked at Lu Jin again after hearing this. Lu Jin said immediately, "The meter is also called the gongchi. It is the measurement used by my Gongshu family. One meter is about three feet of cloth. You can ask someone to measure it."

Lu Jin gave the order, and someone immediately went to measure with a measuring tape. After a while, he came back and said, "General, this place is 855 meters away from the command platform, which is meters short."

Everyone was stunned when they heard this. The distance was almost two miles, and they raised their hands and looked with their eyes. The measured distance was only off by ten and a half feet. The accuracy was really amazing.

While the others were still in shock, Lu Jin had already praised him, "Not bad, you have improved since you first learned it, but you still need to practice more in the future. This time you also took advantage of me. Captain Xu has never learned the eye-jumping method, so he doesn't know the key to it. But it's different on the battlefield, so you still need to practice harder."

"Hey, hey, yes."

Zheng Yulin was somewhat surprised and asked, "General, how do you measure this? Can you teach us this method?"

Xu Da was also curious and asked, "The Marshal said that I didn't know the key and let him take advantage of me. What does this mean?"

Lu Jin immediately laughed and said, "If you want to measure accurately with the eye-jumping method, you need to have an object of known size at the target location as a reference. You just happened to choose the general's platform. The size of the big flag is ten feet long and six feet wide, which is the best reference. You can know the distance with just a glance. It's okay to teach you.

"This method is called the eye-saccade method, but it actually uses similar triangles in arithmetic geometry. The distance between the pupils of a person's eyes is generally two inches, or about 6 centimeters. The distance of an outstretched arm is about 60 centimeters, which is exactly ten times the distance between the pupils.

"Knowing this, you only need to aim the target with the side of your thumb, aim with your right eye first, then close your right eye and aim with your left eye. Then you will see the target jump to the right of your thumb, and then you calculate how far the target jumps to the right, and multiply this result by ten, which is the distance between you and the target.

"For example, if you aim at the big flag, you should jump 25 big flag lengths to the right. If you aim at the base of the platform, you should jump 7 platforms. The platform is 7 feet wide, 85 feet multiplied by is meters, and multiplied by is meters."

Upon hearing this, everyone raised their arms and closed one eye to aim. Just as Lu Jin said, arithmetic geometry could be used in this way. It was really eye-opening.

Li Shanchang also raised his arm and took a look. After listening to Lu Jin's words, he stroked his beard and said, "Confucius advocated learning the six arts of a gentleman: etiquette, music, archery, charioteering, calligraphy, and mathematics. The art of mathematics can calculate the stars in the sky, and can also calculate the acres of land, money, and construction. Nowadays, even the military needs to be proficient in arithmetic and geometry to fight and fire artillery. Confucius is right."

Everyone nodded in agreement when they heard this. Although most scholars looked down on arithmetic and thought it was a minor subject, they now had a lord who was proficient in arithmetic, so they naturally had to praise him when speaking.

This guy is openly talking about Confucius, but in fact he is flattering Lu Jin in disguise, and he flatters people in a way that makes people feel like spring breeze. He is really quite capable. No wonder they say that the sword of a military general cannot compare to the mouth of a scholar.
Xu Da was still pondering the problem. He was not very proficient in mathematics and had no interest in studying this thing. He was more concerned about its application on the battlefield, so he raised another question.

"I see. No wonder the Marshal said that he had taken advantage. But if the battlefield is a vast wilderness and there are no obvious reference points at the target, how can we use this eye-jumping method?"

Lu Jin added, "This requires more practice in peacetime. When there is no war, you should pay more attention to the sizes of various items, such as the width of the city gate, the width of the battlements of the parapet, and the height of the city walls. These can be discovered in advance by spies.

"There are also the dimensions of carriages, windows of watchtowers, and houses of various shapes. If you really can't find a reference, then the enemy army itself can be used as a reference. The width of one person is two feet, ten people is two feet, and the width of a formation of a hundred people is twenty feet. The enemy army formation itself can be used as a reference."

"I see, that's how it is. There will be no problem then. However, I just tried it and I feel that this jumping eye method is still not accurate enough. If you want precision, it's better to measure it in advance. It seems that in future battles, it is better to select the battlefield in advance and let the artillery draw the map." Xu Da said thoughtfully.

Zhu Shou nodded in agreement and said, "That's right. The first chapter of the military book that the commander-in-chief gave to the officers of each battalion says that we can't be lazy. We must personally inquire about the things that should be done and see the terrain that should be seen.

"I still remember when I first joined the army with the Marshal, the first battle was the ambush on Zuo Junbi. The Marshal found the ambush site and checked the terrain a day in advance. He also divided the battle sites of each company and platoon, and led the captains of each unit to identify the land in the middle of the night, and then decided where to start and which road to take.

"It was thanks to the Marshal's careful reconnaissance and command, and the fact that he had familiarized each unit with the terrain in advance, that we were able to defeat Zuo Junbi's invincible army with our weak and vulnerable troops who had never won a battle before."

Xu Da was thoughtful after hearing this. He then realized that Lu Jin had done such a thing when he first fought in a war. No wonder the Marshal had such a high status in the hearts of those veterans. It was not only because of the wisdom and strategies Lu Jin showed when he first joined the army, his ability to lead troops, and even the book of military strategy written by the Marshal himself, which were constantly influencing those middle and low-level officers at the thousand-household level.

While everyone was discussing artillery and range-finding, the shooting range had been set up and the artillery had been aimed and loaded.

Upon seeing this, Yang Huan immediately shouted loudly.

"Report to the commander-in-chief, the artillery has been loaded. The target is a caravan one thousand meters away, with an elevation of five degrees. One solid bullet is loaded. Request to fire!"

"Permission to shoot."

"Yes!" Yang Huan answered loudly, holding up a small red flag only one foot long, and waving it downwards, shouting, "Fire!"

The gunner immediately released his hand that was covering the gunpowder at the firing port, and quickly retreated to the side and rear. Lan Yu, holding the ignition fork, stepped forward and stood to the side of the artillery position. The fuse clamped in front of the ignition fork in his hand was emitting a little red light. He aimed at the firing port and pressed it down.

The smoldering fuse immediately ignited the gunpowder at the firing port. A burst of white smoke suddenly rose up, and in less than a second, a loud bang was heard from the muzzle. A large amount of white smoke suddenly spewed out of the muzzle, and the gun carriage also retreated two or three parking spaces due to the recoil.

The shell also left a trail of white smoke, drew a slightly curved arc in the air, and smashed forward suddenly.
(End of this chapter)