After a night of hangover, Xiao Ming's head hurts a little when he woke up early the next morning.

Today is the first day of the Lunar New Year. According to custom, it is time to visit relatives and friends. If he is in Chang'an, he should have visited everywhere.

However, if there is no need for anything in the Great Yu Kingdom, the vassal kings are not allowed to leave their fiefdoms, especially Xiao Ming is responsible for guarding the border and cannot leave his post without permission.

Now that New Year’s Eve has passed, for Xiao Ming, the first thing he did during the New Year was the Garen ship going to sea.

He arranged the matter of secretly spreading the drama to the people. He went to Bowen Academy. Others could rest during the New Year, but Yue Yun could not rest.

After all, he will be the leader of the three Garen ships.

"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 were two reasons why he told Yue Yun not to go to sea for the time being. One was that the artillery had not yet boarded the ship, and the other was that Yue Yun still lacked the most important lesson in sailing - how to position his position on the sea.

There are only three people in the school, one is Yue Yun, and two are two sailors who are excellent in the seafarers. Xiao Ming gave them the position on the sea as a sailor.

As the name suggests, the responsibility of the Navigator Sail Battleship is to locate the ship's position and guide the Garen ship to the right direction.

Sitting down in front of the three of them, Xiao Ming said, "You can't finish learning these things in one class. Remember, what you want to learn is very complicated, so you all cheer up your spirits, otherwise you may be lost in the sea and never come back."

When Yue Yun and the other two heard this, they nodded heavily because Xiao Ming had never been so serious in school.

At this time, Xiao Ming stretched out his hand, and a servant of the royal palace walked in. He was holding a spherical object in his hand, and a stick was running through the middle of the spherical object, and the bottom was the territory.

"You once asked me what the world is like. Now the world is right in front of you." Xiao Ming pointed to the globe on the table.

This was what he had been preparing during the Chinese New Year. The globe is pure wood and is polished very smoothly on the outside. It marks the earth's latitude and longitude and world map on the globe, especially the vertical and horizontal navigation routes, and even marks where there are reefs.

The map also marks the specialties of each region, which are not as good as corn, cotton, sugar cane, gold, etc.

"Your Highness, is this what you are talking about?" Yue Yun and the other two looked shocked.

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

Xiao Ming nodded. The diameter of the globe was one meter, and the one on it was enough to draw the world map on it.

In order to draw this map, he destroyed more than a dozen globes. Until this one is a little more perfect, he will use it directly, otherwise he would not have waited until now to teach Yue Yun these knowledge.

Xiao Ming pressed the globe with his hand, and the globe began to rotate, and patches of oceans and land flashed in Yue Yun's eyes.

"From the simplest point of view, first of all, you must divide the world into which oceans and lands." Xiao Ming began to talk about the four oceans and the knowledge of the seven continents instilled in Yue Yun.

It can be said that his current education is basically cramming. There is no way to do so. Some things can only be memorized by rote, and this is his strength.

While talking, Xiao Ming showed the location of these regions on the globe, giving a detailed understanding of every piece of land in the world.

After popularizing world geography knowledge, Xiao Ming spoke at the right time.

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

Yue Yun and the other two have become very humble now.

This period of study made them feel like they were just like a frog in a well, and they no longer had the pride they were before.

“This is a quadrant.”

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

This quadrant was invented by British navigator Davis in the late 16th century to measure the latitude of the earth during navigation.

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

Moreover, this kind of quadrant is simple to operate. You do not need to pull a rope to see the sun like using astronomy disk. Instead, you use a stick to project the shadow on the scale. The position of its shadow end indicates the height of the sun, so that the latitude can be calculated.

When manufacturing this quadrant instrument, Xiao Ming put in a lot of effort. In fact, the structure of this quadrant instrument is very simple, one large and one small, two compass are put together, but the legs of the compass are connected by a curved wooden strip, and there is a wooden stick on the connected structure.

The most rare thing about quadrants is the scale problem.

In order to make the scale accurate, the quadrant meter in Xiao Ming's hand was a bit large, almost fifty centimeters long.

After all, the larger the scale interval, the easier it is to draw, and the error is relatively small.

"Your Highness, do you use this to calculate the dimension of the earth?" Yue Yun has already understood what latitude and longitude is.

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

After saying that, Xiao Ming stood 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, span of 1 degree = 111 kilometers on the longitude 1 degree = 111*cosA kilometers on the latitude 1 degree = 111*cosA kilometers, where A is latitude, and the distance between any two points, d = 111.12cos{1/[sinΦAsinΦB ten cosΦAcosΦBcos(λB—λA)]}."

As soon as this 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 was very concise."

Yue Yun and others' mathematics can be said to be zero, and it is impossible to learn advanced mathematics in a short while now, so Xiao Ming will not teach Yue Yun other mathematical knowledge.

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

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

Xiao Ming will also provide him with a latitude and longitude calculation table. Even if he can't calculate it at that time, he can determine his position by comparing the latitude and longitude calculation table, so that he will not go off the sea.

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

The current course is basically the last course 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 in Qingzhou.
Chapter completed!