The map is not difficult to draw, Li Mu can draw it anytime and anywhere. Moreover, he can not only draw ordinary regional outlines, but also draw the main maps of mountains, rivers, contours, etc. Because in junior high school, he was very interested in geography.

Drawing pictures is not a difficult task. The difficulty lies in how to express the concept accurately and not abruptly. How to explain it, how to draw such an accurate map.

Since the idea of ​​drawing a map, Li Mu began to collect information. The so-called "knowing yourself and your enemy" will never be defeated in a hundred battles. To let the Tang people accept the map he drew, first of all, he must know how the Tang people drew a map.

Through the Yu family's doctor Lu Wenfeng and Li Mu had a certain understanding of the map drawing methods of the ancients.

The ancients drew maps, which were very different from Li Mu's previous life. In Li Mu's previous life, technology was already very developed, and drawing maps was very simple. It only takes a high-score satellite to achieve it very accurately. Systems such as 'Beidou' and 'gps', which are composed of dozens of satellites, can even accurately locate objects within one meter, let alone terrain characteristics.

But the ancients had no satellites, and they had their own ways.

First of all, we need to choose a coordinate system. What kind of coordinate system is suitable? In people's vision, there is no better than mountains, rivers and rivers. Therefore, there is the "Shan Hai Jing", which takes mountains and rivers as coordinates and rivers as veins. It starts from mountains and ends from sea, so it is called "Shan Hai Jing". As an encyclopedia of the pre-Qin period, the "Shan Hai Jing" records a large number of mountains, rivers and distances, and the distances of the two mountains are roughly recorded. Although many people think that "Shan Hai Jing" is mixed with myths and legends, the descriptions about geography are still somewhat credible due to the vision that people at that time could reach.

However, geography books like "Shan Hai Jing" are very general after all, and are completely inaccurate and not very practical. With the progress of human society, the requirements for maps have become more and more accurate. At this time, a new drawing method was born.

How to accurately measure it? It is naturally not possible to rely on legs. First, the area is more than a thousand miles away and you can't walk. Furthermore, everyone's "steps" are of different lengths, but they still cannot reach accuracy. Therefore, since Qin Shihuang unified the weights and measures, the concept of "li" was defined. At this time, a new measurement method was born, using a carriage to measure.

In ancient times, maps were also called "geo maps", and this "geo" refers to cars. This set of equipment is called "Jinli Drum Cart". The appearance of Jili Drum Cart in the Qin Dynasty was quite perfect by the Han Dynasty. Its operating method was so clever that in the Tang Dynasty, it was still the main method of drawing maps.

Prepare a carriage, place a drum and a gong on the carriage, divided into two layers, there are two wooden men, and the carriage is equipped with a compass. Every time the carriage travels for a mile, the wooden men will beat the drum, and every ten miles they walk, they will beat the gong.

To draw maps and distance measurement, you only need to pull the "Ji Li Drum Cart" to run all over the country. Record river channels and regional edges, and just record the milestones of the bends to draw the outer outline of the territory.

The data obtained by using the drum truck in the record is not over yet. The important thing is to draw a picture. Anyone can do it by recording the data, but most people cannot do it. Because it involves a relatively deep knowledge for the ancients, the scale, which the ancients called "the plot of the plot".

The first thing to draw the drawing is to draw the grid of equal area on the drawing, and set a ruler for each grid, such as one foot equals a miles. The drawings drawn in this way are already very accurate in a limited small range. But it has a huge flaw, that is, the ancients did not know that the earth was a ball, so there was no concept of longitude and latitude. In a small area, such as a city, or even a small country during the Spring and Autumn Period and the Warring States Period, the map can be relatively accurate. But looking at the entire territory, relying on the middle place can still ensure a certain degree of accuracy. The more it depends on the two ends, the more the earth is a ball, the more it deviates from the curvature.

The map drawn by Li Tai is this problem. He drew a "unprecedented" Tang Dynasty territory map, which included all the current territory of the Tang Dynasty. Before this map, there was no such large-scale map. The map mainly used in the local area is a small area map of the "Fudao County". That is, a relatively accurate map drawn by Jili drawing square and Jili drum cart.

Li Tai, who put these maps together and drew maps of the entire territory of the Tang Dynasty. His ideas could not be wrong, but he did not consider the quartet, which led to inevitable deviations in the map.

Of course, in Li Shimin's eyes, since he had never seen the accurate map that Li Mu had seen in his previous life, Li Tai's map was already amazing to him. However, in Li Mu's eyes, Li Tai's map was so clumsy that it could not be more clumsy and could not be seen at all.

But if you want Li Tai to accept his map, the first thing you have to do is to allow Li Tai to accept the concept of "the earth is round".

How to prove it? It's a question!

...

"I think the earth under my feet is round."

When Li Mu said this, he felt the full question from everyone. This was the most direct method he could think of. Because he could not think of how to explain the fact that the earth was round. Even in his previous life, when there were no satellites, he had debated whether the earth was round, flat or an arc-shaped plane for thousands of years. It was not until Magellan's voyage returned to the origin that the world accepted the fact that the earth was round.

During the Tang Dynasty, sailing across the straits was a matter of life and death. Even Li Mu was unable to do it even if he had a system. So he couldn't prove it, but he had to say it, so he could only be like all pioneers. You think I am a lunatic, I just thought, I said so!

Li Tai widened his eyes and said, "Great...teacher, how can the earth be round?"

"Well," Li Mu cleared his throat and said, "I can't explain clearly, that's what I think." Li Mu gave an example of a bit rogue and said, "If it's not round, I'll ask you, why doesn't the Yangtze River flow eastward, but has been flowing eastward for thousands of years? If the ground is not round, then there will inevitably be a day when it has not flowed, which means it must be round, flowing from west to east, then circled around and returned to the source, so that it can explain why it cannot flow all the time."

Li Tai's brain was a little unable to keep up. He felt something was wrong, but due to the limitations of the times, he did not know what evaporation is, condensation is, and what atmospheric circulation is, so he could not refute Li Mu's point of view. Although he remained suspicious, he was wise to not speak.

Changsun Chong and others watched from the side, and they couldn't find any problems. They didn't even know how to draw maps, and they were just laymen. How could they understand what it meant? They just joined in the fun and wanted to see what the maps Li Mu painted looked like.

Li Mu knew that his statement was untenable, and did not give Li Tai more room to think, so he took out the map he drew overnight. A map of the territory of the Tang Dynasty was the same as Li Tai's map name, but he drew it with carbon strokes cut from animal charcoal, which had a sketching feeling. It looked much more accurate than the map drawn by Li Tai with a fine brush.

This map was completed by Li Mu based on the map he saw in his previous life and was "localized". The place names and regional divisions were all re-drawn by him referring to the existing Tang Dynasty divisions, which is very different from those in his previous life geography class.

The map of his previous life, the division of major provinces, was actually decided during the Yuan Dynasty. Since the Yuan Dynasty was a foreign regime, in order to avoid the local people being too united, he toughly distinguished the areas of the same clan, and there was no natural danger to defend. In this way, even if a place rebelled, it would not be able to hold on to it, which would facilitate the maintenance of rule. The division of the Tang Dynasty was very different from this. If it was taken out directly, Li Tai would not understand it even more.

Although Li Tai was young, he was the most famous master in his world in terms of map attainments. Aside from watching the excitement, while those of experts only looked at the tricks. When Li Tai saw this map, he knew that Li Mu's map was much more accurate than his map. Although he didn't know what was good, he could still tell the advantages and disadvantages.

Li Mu took out another picture, which was the map of Chang'an City he drew. He used the scale setting and drew in detail the area of ​​108 yards of Chang'an City. This picture came earlier than the map just now, because this picture was a construction drawing he drew when he decided to repair the Chang'an alley. He took it out at this time just to give Li Tai a try.

"What do you think? Are you convinced?"

"Abuse!" Li Tai nodded his head suddenly, touching the map, as if stroking the hand of his beloved woman, looking at Li Mu with a gaze, and said, "Mr., can you give this picture to your disciple? I want to take it back and study it carefully."

"It's okay to give it to you, but you have to remember one thing, and remember in the future, there are people outside of people and mountains outside of mountains. Don't make anything, and you feel that you are invincible in the world. Draw a broken map and show off for you. Have I shown off as I am so outstanding? Men, be low-key. When you want to show off in the future, think about whether there is any mentor who surpasses my instructor. If the answer is no, don't show off, so as not to make people laugh."

Li Mu said, glanced at Changsun and said, "You are the same, do you remember? When you want to show off in the future, think more."

Changsun Chong quickly said, "Mr., I no longer have the desire to show off. The longer I follow my mentor, the more I feel my shortcomings. How dare I show off?"

"Just understand." Li Mu pointed to the map and said to Li Tai: "Put it away. If you have nothing to do, work harder and do something early to make my face shine. It will prevent outsiders from hearing that you are my disciple, and I dare not admit it, for fear of being ridiculed."

Li Tai responded timidly, and there was no way. Li Mu had already proved his strength with powerful facts. He had to accept it even if he was not convinced.

"There's another thing." Li Mu suddenly spoke out and said, "Can't you lose weight? You are only eleven years old after the Chinese New Year, and you have to have 200 kilograms now, right?"

"Master..." Li Tai said aggrievedly: "I, I am only 170 kilograms now."

"You 170 kilograms at the age of eleven, do you think it's too little?" Li Mu said angrily: "Changsun Chong, King Yue will be handed over to you. You can practice him as much as you lose weight. During the Lantern Festival, I want to see him lose weight to your current level."

Changsun Chong Tai knew how he lost weight. Li Tai was Li Shimin's son after all, so how dare he treat Li Tai like Li Mu treated him, for what he said: "Mr., King Yue..."

"To me, you are the senior brothers. What else can you do if you teach me? Li Tai, do you think it's not possible?"

Li Tai quickly shook his head and said, "I didn't say anything. Whatever my teacher said is what. The disciple has no complaints and just wants to learn more."

"Hear?" Li Mu waved his hand and everyone retreated. Fang Yiai sent everyone to the door. When he came back, he was stopped by Dugu Jiu. Fang Yiai looked at Dugu Jiu vigilantly and said nervously: "What do you want to do? Do you fight?"

"Yes, not. You go to the same place with me."

“Where to go?”

"You'll know when you leave."

Dugu Jiu was too lazy to talk nonsense, so he walked out with his sword in his arms. Seeing that he was not riding a horse, Fang Yiai didn't ride him either, so he shouted into the study, informing Li Mu that he had gone out with Dugu Jiu, and then trotted behind Dugu Jiu. He did not know how to ease his skills and could not keep up with Dugu Jiu's footsteps.

The two came out of Feng Qiuhuang's back door and walked eastward. They reached an open space, which was not far from the horse farm. Fang Yiai hadn't been here yet, and she felt strange, but she didn't dare to ask. Seeing that there were many craftsmen working here, they were like building another high platform, they began to guess in their hearts, what was they going to do?

This is because he has no habit of reading the Tang Dynasty Daily. If he had read it, he would have guessed it long ago, and this is building a arena.

Dugu Jiu pointed to the ring and said, "Brother decided to hold a ring competition to select the number one Ranger of the Tang Dynasty..."

Fang Yiai hurriedly said, "I must participate. I have wanted to be a ranger. However, I have no confidence in the number one ranger in the Tang Dynasty."

Under the mask, Dugu Jiu was about to turn his eyes to the sky. He really couldn't figure out how Fang Yiai was confident to say such words? Although he was big and thick, in Dugu Jiu's eyes, Fang Yiai was just a three-way guy, the world's number one roster? It's not his turn to be the first hundredth!

"This has nothing to do with you. This is what my brother told me. I came to you to tell you another thing, to repair the alleyway in Chang'an, do you know?"

"I know, what's wrong?"
Chapter completed!