After a night of hangover, when he woke up early the next morning, Xiao Ming's head still hurt a little. Pen % fun % Pavilion www.biquge.info

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

However, if there is no important matter in the Great Yu Kingdom, the vassal king is not allowed to leave the fiefdom, especially Xiao Ming is still responsible for the frontier, and he cannot leave his post without permission.

Now that Chinese New Year's Eve has passed, for Xiao Ming, the first thing of the New Year is the departure of the Galen ship.

Arranged to secretly spread the drama to the people, he went to the Bowen Academy, and other people could rest in the New Year, but Yue Yun could not 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 put on board, and the other was that Yue Yun still lacked the most important lesson in navigation - how to locate his position at sea.

There are only three people in the academy, one is Yue Yun, and two are the two sailors who are better at learning among the seafarers this time, and Xiao Ming gave them the position of navigator at sea.

As the name suggests, the duty of a Navigator sail battleship is to locate the ship and guide the Galen ship 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 below are very complicated, so cheer up this king, otherwise you will probably get lost in the sea and never come back." ”

Hearing this, Yue Yun and the others nodded heavily, because Xiao Ming had never been so serious in the academy.

At this time, Xiao Ming stretched out his hand, and a royal family walked in, holding a spherical thing in his hand, and a stick ran through the middle of the spherical object, and the bottom was the turf.

"You have asked this king what the heavens and the earth are like, and now the heavens and the earth are before 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 pure wood, the outside is polished very smooth, on the globe marked the latitude and longitude of the earth and the map of the world, especially the vertical and horizontal navigation routes, and even marked where there are reefs.

The map also indicates the specialties of each region, which are inferior to corn, cotton, sugar cane, gold, and so on.

"Your Highness, is this what you call the globe?" Yue Yun and the others were shocked.

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

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

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

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

"To put it in the simplest terms, first of all, you have to find out which seas and lands the world is divided into." 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 education, there is no way, some things can only be memorized by rote, and this is his strength.

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

After popularizing the knowledge of world geography, Xiao Ming said that he was on 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.

The three of Yue Yun had now become very humble.

This period of study made them feel that they were just like frogs at the bottom of a well, and they no longer had the pride they had at the beginning.

"This is the quadrant."

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

This quadrant was invented by the English navigator Davis in the late 16th century to measure the latitude of the Earth while sailing.

According to the scientific library, from the 16th century to the early 18th century, this quadrant was the most accurate nautical tool of this period.

Moreover, this quadrant is easy to operate, and instead of pulling a rope to look at the sun like using a astrolabe, a shadow projected on the scale with a stick is used, and the position of the shadow end indicates the height of the sun, so that the latitude can be calculated.

In fact, the structure of this quadrant is very simple, that is, two compasses, one large and one small, are put together, but the legs of the compass are each connected by a wooden strip with a curve, and there is a wooden stick on the connected structure.

The most difficult thing about this quadrant is the scale.

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 easier it is to draw, and the error is relatively smaller.

"Your Highness, do you use this to calculate the Earth Dimension?" Yue Yun has already understood what latitude and longitude are.

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

With 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, span of 1 degree on longitude = 111 kilometers, 1 degree of latitude across longitude = 111 * cosa kilometers, where a is 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 entire head became bigger, and he covered his head in pain, "Your Highness, can you not learn these things." ”

"No, Xiao Ming answered very succinctly."

Yue Yun's and the others' mathematics can be said to be zero, and it is impossible to learn advanced mathematics at once in the past few months, so Xiao Ming will not teach Yue Yun other mathematical 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, he will study much less and focus only 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 looking for it against the latitude and longitude calculation table, so that he will not deviate at sea.

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

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

(To be continued.) )