Imperial Master of the Ming Dynasty

"It's unbelievable."

Zheng He held his long beard that was about to fall off, feeling quite sad.

This means that Jiang Xinghuo has put forward a complete set of demonstration methods to prove the "heliocentric theory". However, it may be difficult to measure it immediately.

In other words, it is precisely because the logic of the argument proposed by Jiang Xinghuo is too impeccable, but it cannot be verified immediately, which makes several people feel regretful.

Looking at the sun above the head hidden in the clouds, even a person as fearless as Zhu Gaoxu still felt the insignificance of a mortal under the sun, moon and stars.

Even though Zhu Gaoxu is nine feet tall and a majestic man, his personal height, quality, and strength in a material sense are still not worth mentioning in the face of broader comparison objects.

"Mr. Jiang, compared with the sun and the moon, we humans are so insignificant. Do we really have a chance to measure the sun and the moon with the power of a mortal one day in the future?" Zhu Gaoxu couldn't help but ask.

"certainly."

Jiang Xinghuo said with certainty: "And I believe that the arrival of that day may not be very far away."

After hearing this, Old Man Zhuo looked at this young man with a calm and confident temperament. For a moment, he unconsciously felt a little convinced.

Perhaps one day in the future, Ming Dynasty will truly measure the sun and moon under the auspices of this young man named Jiang Xinghuo.

Thinking of this, Old Man Zhuo was troubled for a moment.

Old Man Zhuo was hesitating whether to accept Dao Yan's conditions.

After all, when Dao Yan came to see him, he was still skeptical and somewhat disdainful, thinking that Dao Yan was exaggerating.

But now it seems that if he really wants to accept Dao Yan's conditions, he may not look good on his face.

"It's a pity, it's a pity"

Zhuo Jing shook his head, still unsure.

Participating in the disruptive breakthrough in astronomy certainly made Old Man Zhuo excited, but strictly speaking, this was not enough.

——It would be nice if there was something more exciting.

Seeing that everyone was silent, Zhu Gaoxu asked tentatively.

"Mr. Jiang, then, get out of class is over?"

Jiang Xinghuo put away the silver coins in his hand and spent 0.01 second in memory of Li Jinglong.

"Do you still have any questions? No problem, get out of class is over." Jiang Xinghuo said.

Old Man Zhuo was still immersed in his own thoughts, but Zheng He insisted on asking a question even though his hands were numb.

"Since Mr. Jiang has the ability to measure the sun and the moon, there is a question in his chest that has been bothering him for a long time. It's really hard to express."

"Let's talk about it."

Jiang Xinghuo looked at this strange red-faced man with a long beard.

Well, although it’s not hot today, it’s still noon. It seems like red sweat is flowing from his forehead?

Jiang Xinghuo twitched the corner of his mouth and pretended not to see it.

Zheng He spoke with difficulty through his long beard: "That night I saw Mr. Jiang's spherical chart. It was somewhat similar to an armillary sphere, but not very similar to something made by the Yuan Dynasty. However, the names of cities, places, and countries were very precise. Gao, I would like to ask Mr. Jiang how to position it during production?"

"Latitude and longitude."

Jiang Xinghuo said simply.

"Latitude and longitude?" Zheng He chewed on this new term.

The so-called latitude and longitude is easy to understand. It refers to the latitude and longitude of the sky, but what does latitude and longitude mean?

Seeing that they were a little confused, Zhuo Jing added: ""The Book of Rites of Great Dai·Yi Benming" records: The east and west of the land are latitude, and the north and south are longitude. Are the longitudes and latitudes mentioned by the little friends the 'Arctic High' and 'Lidian'? ?”

The so-called Arctic High is the initial concept of latitude in ancient China. Of course, it should be pointed out here that there are still slight differences between the Arctic High and the later concepts of latitude.

The principle here is that Polaris is on the extension line of the entire earth's axis and is very far away. Therefore, if you observe Polaris from any angle in the northern hemisphere, the angle between this angle and the horizon is equal to the elevation angle of Polaris. , which is approximately equal to the latitude of the place.

In other words, if the North Star is above your head, congratulations, you've reached the North Pole.

If Polaris is on the horizon, you are at the equator.

In the same way, if you look up at the sky at 45 degrees and find the North Star, it only means that you are at 45 degrees north latitude.

As for the two concepts of latitude and longitude, China is currently better at measuring latitude. The most typical one is Guo Shoujing's measurement of the earth. I won't go into details on this. As for longitude, the so-called "mile difference" was proposed by Yelu Chucai, the author of "Journey to the West" mentioned before, but no actual measurement was carried out.

This is because latitude is produced naturally. The equator is zero latitude, and the poles are ninety latitudes. There are fixed standards, but longitude is completely different. There is no natural zero longitude in the world, and we can only rely on human beings themselves. divided by standards.

Jiang Xinghuo nodded slightly and said, "It means the same thing. The latitude and longitude are equivalent to the tic-tac-toe grids. As long as you determine which tic-tac-toe grid you are in, you can determine your specific location."

The sea is magnificent and contains countless stormy waves.

It is obviously a very bad thing if a sailing ship is lost in the sea.

Therefore, Zheng He realized almost instantly the importance of longitude and latitude for ocean navigation.

"It's easy to say that the North Pole is high. It can be easily measured. Even on a ship, a skilled sailor can use a star board to measure it."

Zheng He wondered: "But how can we measure the mileage, that is, the longitude?"

Here we want to talk about why, in Jiang Xinghuo’s previous life, Zheng He did not discover America during his seven voyages to the West? We are obviously just across the sea from Africa!

The reason is that China, India, Arabia and other regions used star-drawing techniques and water compasses in this era.

The compass used for navigation in the Yuan and Ming dynasties was a twenty-four-position water compass. The compass divided the circle into two-fourteen equal parts, with twelve earthly branches and ten heavenly stems, except Wu and Ji (which belonged to earth and were located in the center), leaving eight , and the four oblique directions of the Bagua are named one by one, as twenty-four needles, so that the direction can be accurately indicated.

It's a bit similar to the cheating mini-maps in later online games. On a circular mini-map, you are shown the directions of several targets, but you don't know how far away they are or what's ahead.

Navigating according to this twenty-four-needle water compass, the results are similar to those recorded in the "Zhenla Fengtu Ji" of the Yuan Dynasty.

"Opening the ocean from Wenzhou, we traveled to the ports of Fujian and Guangzhou, crossed the Qizhou Ocean, and passed the Jiaozhi Ocean to Champa. From Champa, we can reach Zhenpu in half a month with a favorable wind, which is its territory.

He also traveled from Zhenpu to Kunshen Needle, crossed the Kunlun Ocean, and entered the harbor. There are dozens of harbors, but only the fourth harbor can be entered. The rest are shallow and cannot be accessed by giant boats. However, they are all covered with vines, ancient trees, and yellow sand. The white reeds are not easy to identify in a hurry, so the boatman finds it difficult to find the harbor. Traveling north from the port, you can follow the water for half a month. When you reach the place called Chanan, it belongs to the county..."

The twenty-four-needle water compass will tell you that you can reach Zhenpu by following the Dingwei needle, but you have no idea what you will encounter on the way.

The destination pointed by the direction of this water compass is not born with it, but has been explored by generations of sailors.

Therefore, in the Ming Dynasty, it was precisely because of the lack of the concept of "latitude and longitude" that it was impossible to accurately locate in the vast sea. We could only follow the coastline, otherwise we would get lost.

This was the case for Zheng He's voyages to the West, so he could only reach Africa as far as he could. It was impossible to discover the American continent across the sea. The reason was that neither the star-finding technique nor the water compass had been explored there before, so naturally there was no information. Available for reference.

Well, there is a wall of air ahead. Brave man, please go back.

So why were there so many pirates around the Ming Dynasty and the Western Age of Discovery? For example, Wang Zhi, the captain of the Wufeng ship, and the Zheng family and his son, etc.

It is because during this period, all merchant ships in the world traveling between Western Europe, Arabia, Tianzhu, and China can only go along the coastline, relying on the stable routes and supply points explored by predecessors to ensure that they will not get lost. in the ocean.

Jiang Xinghuo said: "There are no ways to measure longitude."

"Oh? Please tell Mr. Jiang in detail."

"A day has twelve hours, is that okay?"

Several people nodded in unison, this is no problem.

"We have said before that the earth is rotating, that is to say, it rotates once a day, so each hour is one-third of a right angle (30°), and we only need to use the sundials in two places to determine By judging the time difference, we can obtain the rough longitude difference on land. After repeated testing, we can finally obtain it on the land of the Ming Dynasty through exhaustive methods." Jiang Xinghuo said.

"That is to say, if it is noon in Nanjing, it is not noon in Chengdu or in the morning, so just measure the time difference?" Zheng He still felt something was wrong, "Mr. Jiang, you can measure it slowly on land, and you will be wrong. It doesn't matter, after all, the cities are fixed. But the sea is floating, so how can we judge the longitude?"

"Lunar distance method."

Looking at the red-faced man, Jiang Xinghuo softly uttered these three words.

And when Jiang Xinghuo inadvertently saw the other party lifting up his long beard, Jiang Xinghuo had some guesses in his mind.

Why is this man so interested in sailing?

However, Jiang Xinghuo had no time to think about it and continued: "The so-called lunar distance method uses the movement of the moon to measure longitude. Because the relative position of the moon in the sky changes every moment, one moon moves approximately every half an hour. The distance in diameter. So as long as you observe the moon in two places and accurately record the time when it moves to a certain position, you can calculate the longitude difference between the two places."

"And this only requires a "Big Star Sky Chronicle", that is, a complete star catalog, with a complete background star map used as a background reference for the moon, to record the fixed movement patterns of the moon and other stars. This is The basis of the 'lunar distance method' is to calculate which star the moon went to at a certain time, which can be used as a reference for the time of departure."