After dinner, Chen Huaixiu invited the girls to go out and watch the stars together.

Although, in this era, even in big cities, there is not too much light pollution, and the girls are accustomed to the sky full of stars. But the bright starlight sprinkled on the sea, rippling the endless silver waves. This magnificent scene is the only one they have ever seen in their lives.

It was March, and the night breeze on the sea was only slightly cool, and there was finally no need to worry about sunburn. A few girls wrapped in cloaks were on the deck, admiring the beautiful scenery of the sea and sky while laughing and chatting privately.

Even the eldest princess, who had not shown up since boarding the ship, came out of the cabin and leaned lazily on the recliner, sipping fine wine while watching the stars in the sky blinking, just like Zhao Lang's big eyes.

It’s already the third day since we’ve been apart, and I miss him.

Zhao Hao was a smart man and knew that it was not a good idea to go find the girls or talk to his godmother at this time.

He would rather ask Zheng Ruozeng how to use the Qianxing board.

Seeing the two of them on the top deck, gesturing with the wooden board, Zhang Xiaojing felt very itchy. But she had been pestering Zhao Hao all afternoon, so how could she dare to go up to him again?

She had no choice but to retract her envious gaze and continue talking about girls.

Ma Xianglan, who was standing by, saw Xiao Zhuzi's expression. Secretary Ma laughed inwardly. Miss Zhang had just left Jiangnan, and her thoughts were already active again.

Thanks to Sister Ma’s encouragement during this period, Xiao Zhuzi did not give up and finally adjusted her strategy, which led to a turning point.

In the eyes of the shrewd Sister Ma, the Romance of the Three Kingdoms is naturally more lasting than the Chu-Han Contention. If she works harder and creates the Seven Heroes of the Warring States Period, her life will not be so easy.

However, we also have to consider the prince's ability to bear it. It is better to reduce it and make the Five Hegemons of the Spring and Autumn Period.

As for her, she is naturally a patriot who never seeks hegemony and is harmless to people and animals.

~~

"A-choo, A-choo..." On the top deck, Master Zhao sneezed several times, and Gao Wu quickly put a cloak on him.

Zheng Yiluan also put a cloak on his father.

"It's okay." Zheng Ruozeng waved his hand, signaling him not to disturb him. Then he continued to demonstrate to Zhao Hao how to use the 'Star Pulling Board'.

A set of star-pulling boards is made up of twelve square ebony boards, the largest of which is about 24 centimeters long, called the "twelve fingers". Each board is two centimeters smaller, until the smallest board, which is two centimeters long, is called the "one finger". A rope about 72 centimeters long is passed through the center of the board. It is very simple to make. Zheng He used it to measure the height of the stars and the direction.

Don't be fooled by its unprepossessing appearance. There are only a few people in the Ming Dynasty who can use it. Zhao Hao had previously asked Uncle Mi and Elder Niu Ma about it, and they all knew about its existence. But the Star Pulling Board alone was useless, and it also needed to be used in conjunction with the Star Pulling Map. None of them had ever seen the Star Pulling Map, so naturally they didn't know how to use the Star Pulling Technique.

It was during the time when Zheng Ruozeng was in Hu Zongxian's court that he used the excuse that a naval battle was needed to fight against the Japanese pirates and dug out several star maps from the storage room of the Southern Military Department, which included the routes for the sea transportation of grain during the Yuan Dynasty.

It was with the help of these star maps that he was able to sail across the waters of the Ming Dynasty and write the immortal thirteen volumes of "Chou Hai Tu Bian".

~~

"The star-pulling technique is actually very simple." Zheng Ruozeng said as he looked up at the starry sky in the north, picked up the 'six-finger' board in his right hand and stretched out his right arm.

Then, with your left hand, pick up the string that is threaded through the center of the board and place it in front of your eyes.

"First look at the bottom edge of the board, level it with water, then check if the top edge of the board is flush with Beichen." He shook his head slightly and said, "It's too wide, it's blocking Beichen. Change to four fingers."

Zheng Yiluan quickly changed to the 'four fingers' board and repeated the above movements. Zheng Ruoceng saw the North Star appear on the upper edge of the board and said in a deep voice: "North Star Four Fingers."

His second son quickly wrote down the new ship lamp... After being able to blow glass by himself, this portable, windproof and rainproof kerosene lamp was no longer difficult to manufacture, except that it still used lamp oil as fuel. Especially in windy and rainy weather at sea, it was a great lighting tool for the crew!

Zheng Ruozeng used the same method to observe the positions of Vega and Northwest Busi. He put on his reading glasses and looked up a booklet, which was the "Beiyang Qianxing Atlas" he copied from the Military Department.

Finally, he turned to the page he was looking for and read slowly: "Crossing the Black Water Ocean, look at the North Star, which is four fingers above the water, the Vega Star in the east, which is seven fingers above the water, and the Bushi Star in the northwest, which is eleven and a half fingers above the water. Sir, we are not off course."

Everyone breathed a sigh of relief after hearing this. The sea was boundless and they were sailing on a long sea route. Fifty ships were like a group of ants, and everyone was worried that they would get lost in the vast sea. That would be terrible.

Young Master Zhao was not too worried. According to his limited knowledge of geography, they had already entered the Kuroshio Current, which is the range of the Japan Warm Current.

Even if he was lost, the most likely possibility was that he was carried to Nagasaki, Japan by the ocean currents, just like Wang Zhi.

After listening to Mr. Kaiyang's explanation, Zhao Hao basically understood the principle of star-pulling - in a word, the elevation angle of the North Star observed at a certain place on the earth is the latitude of that place... This is a very simple geometry proof problem and there is no need to elaborate.

In order to increase the accuracy, it is also necessary to observe other constellations. The navigator records the data observed during the voyage and obtains a star map. In this way, later generations can use the data of their predecessors to determine their own position.

This is the same principle as the octant and sextant invented in Europe nearly 200 years later, but the latter is more accurate.

Zhao Hao asked Bei Peijia to make a trial octant first, and ordered him to use the data from the Nanjing Imperial Astronomical Observatory to try to compile a primitive "Astronomical Calendar". However, at present, even basic map drawing is not standardized, and even the concept of longitude and latitude has not been introduced, so it is naturally impossible to rely on it in a short period of time.

There is no way, there are too many classes to attend. You have to eat one bite at a time.

However, Zheng He made seven voyages to the West, all of which were based on the astrology and the compass, and he never got lost during the total voyage of hundreds of thousands of miles. So for a long time, the astrology was completely trustworthy.

Mr. Kaiyang also told Zhao Hao that by using the Danyou needle, he could reach Tamluo at three o'clock in the morning.

"When it's almost daybreak, you can see the mountain on Jeonra Island." Zheng Ruo Zeng introduced: "Jeonra Island is also the most important reference on this route. Once you see it, you can use the single-pointed needle to turn northwest, and after thirty o'clock, you can see the Chengshan head of Weihaiwei."

~~

The next morning, Zhao Hao had something on his mind, so he didn't stay in bed for the first time. Before daybreak, he washed and dressed neatly under the help of Secretary Ma, ran to the deck, and set up a telescope towards the bow.

After enjoying the magnificent sunrise at sea, he discovered a black spot on the sea horizon.

Looking through the telescope, I saw that the island looked like a tomb with a bulge in the middle. Mr. Zhao had watched "My Name is Kim Sam-soon" and recognized it as Tamra at a glance. As for the bulge in the middle, it was the legendary BBQ Mountain... Oh no, Halla Mountain.

The North Koreans believed that standing on this mountain, they could reach the Milky Way, hence the exaggerated name.

Tamra is the Jeju Island of later generations. However, the name "Jeju Island" was changed privately by King Gojong of the Goryeo Dynasty, but both the Yuan and Ming dynasties thought it was too troublesome to change the name and still used the original old name.

Although the Joseon Dynasty, now the number one licker of the Ming Dynasty, wanted to change its name several times, its father refused to agree because of its annoyance. Therefore, the Joseon Dynasty could only call the name Jeju Island behind closed doors, and still had to use "Tamra" when communicating with the father country.

It's the same thing as 'Okay, Vincy'.

Zheng Ruozeng also appeared beside Zhao Hao, looking at the visible Jeonra Island, and said gloomily: "This island looks small from a distance. But in fact, it is 150 miles from east to west and 60 miles from north to south, as big as two Kunshan counties. And it has been a good place for horse breeding since ancient times."

Zhao Hao nodded to show that he understood.

"Originally, Tamra was an independent country that had been paying tribute to me since the Tang Dynasty. Later, it was annexed by the King of Goryeo." Zheng Ruozeng stared at the lush green island and said quietly, "Later, it was occupied by the Mongols and used as a place to raise horses and exile prisoners. When my Emperor Taizu drove out the Tartars, Goryeo took the opportunity to submit a "Tamra Plan Report" and demanded that Tamra be handed over to them, promising to continue to pay tribute to the Ming Dynasty according to the Yuan Dynasty's horse herding management model."

"In order to get Emperor Taizu's approval, they used a trick to reduce the circumference of Tamra by ten times and its population by ten times in their memorial. Emperor Taizu thought it was just a tiny place isolated overseas, and the island was still under the control of the Mongols at the time, so he generously gave it to them."

"My vassal's vassal is not my vassal." Young Master Zhao muttered. In addition to its superior natural conditions, Jeju Island also has an excellent geographical location. It is located at the crossroads of the sea between Ming Dynasty, Korea and Japan, and is an excellent transit point for Sino-Korean-Japanese trade.

Emperor Taizu was so smart, how could he let the Koreans take this place away?

Oh, by the way, Mr. Zhu is always against not going to sea, so what does he need an island for?

"But fortunately, the current Joseon is ten times more submissive than Goryeo was back then. They are just licking the ass of the Ming Dynasty. We can go to this island whenever we want and do whatever we want. There is no Ming Dynasty law to restrict us." Zheng Ruozeng, who left the land, showed his wild side.

He is the number one supporter and advocate of Zhao Hao's maritime strategy, and believes that only by defeating the enemy at sea can the maritime security of the Ming Dynasty be completely guaranteed. Only by crossing the sea and severely teaching Japan a lesson, knocking them down, and making them call the Ming Dynasty daddy every day like North Korea, can the glory of the Celestial Empire be restored!

Tamra was the forward base that Zheng Ruo had planned for Zhao Hao. Whether it was used as a commercial base to earn endless silver from the Japanese, or as a future military base, it would be a great place to raise troops and horses and invade Japan.

"On the way back, let's go to the island and take a look, and then make a long-term plan." Young Master Zhao smiled and comforted Zheng Ruozeng, who was in a hurry.

"There's nothing to worry about, just be tough! The tougher you are, the more comfortable they will be." Zheng Ruozeng stretched out his hand and clenched his fist, as if he was holding Tamra in his hand, and said, "Such a good place, how have they run it into such a mess? Just give it to us obediently!"

ps. There is one more update, but it still has more than a thousand words, so please wait.