Chapter 282

After a night's hangover, when he got up the next morning, Xiao Ming's head still hurt.

Today is the first day of the lunar new year. According to the custom, it is time to visit relatives and friends. If he is in Chang'an, he should visit everywhere.

However, in the state of Dayu, if there was no important thing, the vassal king was not allowed to leave the fiefdom, especially Xiao Ming, who was also responsible for guarding the border, and he was not allowed to leave his post without permission.

Now new year's Eve is over. For Xiao Ming, the first thing in the new year's Eve is the sailing of Galen.

He arranged to spread the drama to the people secretly. He went to Bowen college. In the new year, other people can have a rest, but Yue Yun can't.

After all, he will be the leader of the three galleons.

"Your Highness, is today the last lesson before going to sea?"

In the morning, Yue Yun was waiting in the school.

Xiao Ming nodded. There are two reasons why he asked Yue Yun not to go to sea for the time being. One is that the artillery has not been on the ship, and the other is that Yue Yun still lacks the most important lesson of navigation - how to locate his position on the sea.

There are only three people in the school. One is Yue Yun, and the other two are the two sailors who have learned better this time. The position Xiao Ming gave them at sea is a navigator.

As the name suggests, the duty of the sailor is to locate the ship and guide the Galen to the right direction.

Sitting down in front of the three, Xiao Ming said, "you can't learn all these things in one class. Remember, what you're going to learn is very complicated, so cheer up for us. Otherwise, you may be lost in the sea and never come back."

After hearing the speech, Yue Yun nodded his head, because Xiao Ming had never been so serious in school.

At this time, Xiao Ming stretched out his hand to the outside, and a servant of the royal family came in. He was holding a ball in his hand. There was a stick running through the middle of the ball, and at the bottom was the territory.

"You once asked me what the heaven and earth were like. Now the heaven and earth are in front of you." Xiao Ming pointed to the globe on the table.

This is what he has been preparing during the Chinese New Year. The globe is made of pure wood, and the outside is polished very smooth. The longitude and latitude of the earth and the world map are marked on the globe, especially the vertical and horizontal navigation routes, and even the hidden reefs are marked on it.

In the map also marked the specialty of each region, as corn, cotton, sugar cane, gold and so on.

"Your Highness, is this what you call a globe?" Yue Yun's face was shocked.

What this globe presents is absolutely a subversion of their thoughts.

Xiao Ming nodded. The diameter of the globe is one meter. There is enough space on it for Xiao Ming to draw a map of the world.

In order to draw this map, he destroyed more than ten globes. Until this one was a little more perfect, he directly used it. Otherwise, he would not wait until now to teach Yue Yun this knowledge.

Xiao Ming's hand on the globe, the globe began to rotate, a piece of land and sea in Yue Yun's eyes flashed.

"From the simplest point of view, first of all, you need to know which oceans and which lands the world is divided into." Xiao Ming began to teach Yue Yun the knowledge of four oceans and seven continents.

It can be said that his current education is basically cramming education, there is no way, some things can only be rote, and this is his strength.

While talking, Xiao Ming showed the location of these areas on the globe, and explained in detail the knowledge of every land in the world.

After popularizing the knowledge of world geography, Xiao Ming made a point.

"Now that you know that the world is big and there are many countries, it's time to teach you how to position yourself at sea." Xiao Ming said.

Yue Yun and his three have become very modest.

This period of study makes them feel like a frog in the well, no longer proud.

"This is the quadrant."

After the globe, Xiao Ming took out the same thing that was necessary for navigation in this era, the quadrant. The real name of the quadrant in his hand is Davis quadrant.

This quadrant was invented by British navigator Davis at the end of the 16th century. It is used to measure the latitude of the earth when sailing.

According to the records in the science and Technology Library, this quadrant was the most accurate navigation tool in this period from the 16th century to the early 18th century.

Moreover, this quadrant is easy to operate. It is not allowed to look at the sun with a string like a astrolabe. Instead, it uses the shadow cast on the dial by a stick. The position of the shadow end indicates the height of the sun, so that the latitude can be calculated.

Xiao Ming made great efforts in manufacturing the quadrant. In fact, the structure of the quadrant is very simple, that is, two compasses, one big and one small, are put together. However, the two legs of the compasses are connected by a curved wooden bar, and each of them has a wooden stick.

The most difficult part of the quadrant is the scale.

In order to make the scale accurate, the quadrant in Xiao Ming's hand is a little big, almost 50 cm long.After all, the larger the scale interval, the better the drawing, and the error is relatively small.

"Your Highness, is this the only way to calculate the earth dimension?" Yue Yun already knows what longitude and latitude are.

Xiao Ming nodded, "this is just an instrument. Now you have to learn how to calculate longitude and latitude, that is, the formula of longitude and latitude."

After that, Xiao Ming got up and stood in front of the blackboard.

He wrote on the blackboard, "latitude 1 degree = about 111km, latitude 1 minute = about 1.85km, latitude 1 second = about 30.9m, longitude span 1 degree = 111km, latitude span 1 degree = 111 * cosa km, where a is the latitude, the distance between any two points, d = 111.12cos {1 [sin Φ asin Φ B + cos Φ ACOS Φ bcos (λ B - λ a)]}."

As soon as the formula came out, Yue Yun's whole head became big. He covered his head in pain. "Your Highness, can you not learn these things?"

"No, Xiao Ming's answer is very concise."

The mathematics of Yue Yun and others can be said to be zero. Now it is impossible to learn advanced mathematics in recent months. Therefore, Xiao Ming will not teach Yue Yun other mathematics knowledge.

He only let Yue Yun learn to calculate dimensions in this way, which means that he only needs to learn how to use this formula to calculate longitude and latitude.

In this way, his learning will be greatly reduced and he will only focus on this formula.

Xiao Ming will also provide him with a calculation table of longitude and latitude. Even if he can't work it out at that time, he can find out his position by referring to the calculation table of longitude and latitude, so that he won't deviate at sea.

In the past, Xiao Ming thought that navigation was a very simple thing, but after learning the knowledge of navigation, he realized that it was a very complex systematic knowledge. In the 18th century, walking along the coastline was not called navigation.

Now this course is basically the last one after Yue Yun went to the sea. From then on, he will go to the sea, for trade, for the boundless wealth, and for the most primitive capital accumulation of Qingzhou.

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