Iron Dynasty

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

Today is the first day of the new year. According to the custom, when visiting relatives and friends, if he is in Chang'an, he should visit everywhere.

However, in the Great Yu Kingdom, if there is no important matter, the vassal king is not allowed to leave the fief, especially Xiao Ming is also responsible for guarding the border, and he cannot leave his post without authorization.

Now that New Year's Eve has passed, for Xiao Ming, the first thing to do in this new year is the Galen ship going to sea.

Arranged to secretly spread the drama to the people, he went to Bowen College, others can rest during the New Year, but Yue Yun can't rest.

After all he will be the leader of the three Galen 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 asked Yue Yun not to go to sea for the time being. One was that the artillery had not yet been on board, and the other was that Yue Yun still lacked the most important lesson in sailing—how to position himself at sea .

There are only three people in the school, one is Yue Yun, and the other two are the two sailors who have studied better among the sailors this time. The positions Xiao Ming gave them at sea were navigators.

As the name suggests, the duty on the Voyager's Sail is to locate the ship and guide the Galen in the right direction.

Sitting down in front of the three of them, Xiao Ming said: You can't finish these things in one class, remember, the things you have to learn are very complicated, so cheer up for this king, otherwise you are likely to get lost. Never come back at sea.

Hearing the words, the three of Yue Yun nodded seriously, because Xiao Ming had never been so serious in school before.

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

You once asked me what this world is like, and now this world is 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. This globe is made of pure wood, and the outside is very smooth. The latitude and longitude of the earth and the world map are marked on the globe, especially the vertical and horizontal navigation routes. There are even reefs marked on it. .

The specialties of each region are also marked on the map, such as corn, cotton, sugar cane, gold and so on.

Your Highness, is this the globe you're talking about? Yue Yun and the three looked shocked.

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

Xiao Ming nodded. This globe is one meter in diameter, and it is enough for Xiao Ming to draw the world map on it.

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

Xiao Ming's hand pressed on the globe, the globe began to rotate, and pieces of ocean and land flashed in Yue Yun's eyes.

From the simplest point of view, first of all you have to figure out which oceans and which lands the world is divided into. Xiao Ming began to talk about the four oceans and the knowledge of the seven continents to instill in Yue Yun.

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

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

After popularizing the knowledge of world geography, Xiao Ming spoke on time.

Now you already know that this world is huge and there are many countries, now it's time to teach you how to position yourself at sea. Xiao Ming said.

The three of Yue Yun became very humble now.

During this period of study, they felt that they were just like frogs in the bottom of the well, and they no longer had the arrogance they once had.

This is the quadrant.

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

This quadrant was invented by the English navigator Davies at the end of the 16th century to measure the latitude of the earth while sailing.

From the sixteenth to the early eighteenth centuries, this quadrant was the most precise nautical tool of this period, according to records in the Technobank.

Moreover, this quadrant is simple to operate. Don't pull a rope to look at the sun like using an astrolabe, but use a stick to cast a shadow on the scale. The position of the shadow end indicates the height of the sun, so that the latitude can be calculated. .

Xiao Ming put a lot of effort into making this quadrant. In fact, the structure of this quadrant is very simple, just two compasses, one large and one small, put together, but each of the two legs of the compass uses a curved wooden strip. connected, and each has a stick on the connected structure.

The most difficult part of the quadrant is the scale problem.

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

After all, the larger the scale interval, the better the painting, and the error is relatively small.

His Royal Highness, do you just use this to calculate the dimensions of the earth? Yue Yun already understood what latitude and longitude are.

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

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

He wrote on the blackboard, 1 degree of latitude = about 111 km, 1 minute of latitude = about 1.85 km, 1 second of latitude = about 30.9 m, 1 degree of longitude span = 111 km, 1 degree of longitude spanned on latitude = 111* cosA kilometers, where A is the latitude, 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 succinct.

The mathematics of Yue Yun's and others can be said to be zero, and it is impossible to learn advanced mathematics in the past few 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 latitude and longitude.

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

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

In the past, Xiao Ming also thought that sailing was a very simple thing, but after learning the knowledge of sailing, he realized that it was a very complex systematic knowledge, and in the eighteenth century, walking along the coastline was not called sailing.

The current course is basically Yue Yun's last course after going to sea. From then on, he will go to the sea, for trade, for the boundless wealth, and for the most primitive accumulation of capital in Qingzhou.