Just as Tian Xiu was pondering what other uses the Polaris altitude difference could use, Shang Cheng was wandering around the room irritably.

This is his little study. Like his residence in Yanshan, this study is actually an upper room, and through the side door through the hall, it is his bedroom. It's just that when he was in Yanshan, he basically didn't have much leisure, and he was busy reading official documents when he returned home every day, or he was looking for someone to come over to talk about business, and he often had to be busy until the middle of the night before he could yawn and climb onto the kang to rest. Now, he's finally free. Nowadays, there are no official documents waiting for him to sign, and no one is bothered with trivial official affairs, except for the military newspaper that must be issued by the military department every ten years, there is no piece of paper in this room that has anything to do with military and political affairs. This taught him to feel at ease and uncomfortable at the same time. He has become accustomed to a busy life, and when he suddenly becomes idle, he will inevitably have a sense of loss. Moreover, he was a commander in Yanshan before, and he was in charge of all matters related to the military and political affairs of Yanshan, and he led the army and the people in all matters, and some places let him show his strength, and in a blink of an eye, he was arranged here to "recuperate", with neither power nor soldiers in his hands, the key is that there is nothing to do, and there is naturally a gap in psychology. Even though he had anticipated this situation before entering Beijing, and was mentally prepared to recuperate, when it really happened, he still found that he was far from being as strong as he imagined.

Yes, when he realizes that he will be idle for a long time to come, his emotions are uncontrollably low. Just moved to this Zhuangzi, which represents the "emperor's grace", he even poured bitter water in front of Xue Xun and Zhenqian, who came to congratulate him, bluntly said that the prime minister's public office was unfair, and complained that the court unloaded the mill and killed the donkey. Fortunately, only Xue Xun and Zhenqian were present at the time, both of whom were his close friends, so these excessive words did not spread. Otherwise, although the court will not demote him because of a few complaints, it is impossible to let him go casually, it is estimated that it will make him suffer some hardships and help him have a better memory.

Zhen Qian and Xue Xun were very sympathetic to his plight. But none of them could help, and could only comfort him and encourage him with words. They also cited some figures in history and in this dynasty to prove the truth that "the heavens will descend on the people, and they must first work their muscles and bones if their hearts and minds are exhausted"; He is a capable person, although he is now idle, but there is no need to worry about it, there will always be a day when "if you don't fly, you will soar into the sky". Of course, while comforting him, they also tactfully reminded and warned him that beware of misfortune coming out of his mouth; There are some things that can be thought of and not said, and it is best not to think about them at all.

With the comfort of his friends, his mood improved slightly.

However, a friend's words did not really solve his problem. He is only in his early thirties, it is a good time for him to be in the prime of life, he is round and strong, he can eat, sleep and kick, but he is forced to "recuperate" in this broken Zhuangzi, he has a good strength and full of pride but he can't show it, and he will hold back his illness if he is not sick! In particular, the sadness caused by the injustice, the grief and indignation of having to bow one's head under the roof, and the melancholy of not being able to repay one's ambition all made him feel distressed......

Fortunately, he is not alone in the world. He also has his family, Yue'er, Pan'er, Da Ya and Erya, as well as Sang Xiu and Zhennu, they may not be able to understand his feelings, but they are all caring for him in their own ways. Yue'er would come over to talk to him almost every morning and evening; If she found him reading or doing something else, she would not disturb him, but would go back quietly; But she would leave a message so that he knew she hadn't forgotten him. Pan'er and Da Ya usually don't come to the front yard, but they make his three meals a day, and they all know what he likes to eat. There are also Sang Xiu and Zhennu, when they see that he is not in a good mood, they will sing him tunes and dance for him. It's a pity that they don't know yet, he can't understand singing books and big plays, and he can't see whether the neon dance of real slaves is good or bad. In fact, every time at this time, he watched them sing and dance with an intoxicated smile, and did not hesitate to praise himself. He could feel their concern for him. In any case, they are also caring for themselves by doing so; It's just that the way is wrong.

Speaking of his family's concern for him, he can't fail to mention Erya.

After he settled in Zhuangzi, he wanted to find something to do for himself because he was too idle. He was only thirty years old, he thought, and it seemed early to start writing his memoirs; If you write "The Art of War", you will teach people to laugh off their big teeth when you say it. Fortunately, some time ago, there was a reason for Gao Xiaosan to go to sea, so he simply made a fuss about the navigation. But the scope of navigation is too extensive, and the manpower and material resources required are incalculable, and he can't do it alone. So he went to the military department, found Zhenxiang, and told him about it. What he meant was to mobilize Zhenqian, hoping that the Ministry of War would spend tens of millions of dollars to support him in developing navigation technology. But after hearing him, Zhenqian immediately shook his head like a rattle. Even if he said it wildly, swore to pat his chest, and promised that these techniques would inevitably bring countless benefits, Zhenqian just didn't agree. Because the two of them are too familiar, Zhenqian told him without minus that there is a history of people who are not human inside and outside by the Ministry of Engineering, so his reputation as Shang Yanshan is very bad in the government and the opposition; At this time, he was pouting with the military department to develop what navigation technology, was it because he thought the military department was an eyesore?

With all that said, what else could he say? He couldn't do anything except spit on the gate of the yamen of the military department, and then shout two cruel words. In the end, he had to go home in disgrace.

He touched a gray nose in the military department, and naturally he didn't have a good face when he got home. The matter was soon known to Erya. The little girl didn't say a word, and immediately taught the tent room to prepare 5,000 yuan in cash, and also released bold words on the spot: The military department is reluctant to break the money, so we will do it ourselves! It doesn't matter if it succeeds or not, as long as he is happy; Even if he loses his family, it's just a big fart.

Erya's opinion was immediately unanimously approved by the whole family. If the money is gone, it will be earned, as long as he can be happy, it is better than anything else.

So, he began to swim in the sea of nautical technology. These days, he basically doesn't read much, and he doesn't bother to learn calligraphy, except for playing a few games of Go with Gu Shi from time to time to relax, he basically stays in this study. Right now, his "research results" are littered everywhere in the study. On the table, on the bookcase, on the chair and on the coffee table, you can see some paper with words written everywhere, warm currents, cold currents, monsoons, Tropic of Capricorn, equator, latitude and longitude, tides, the moon, sunspots, El Niño...... Regardless of whether it has anything to do with navigation or not, everything that can be remembered is recorded by him, and it is everywhere when he catches it and rakes it everywhere. He doesn't let people tidy up; Of course, they can't figure it out. All they know is that his research, as he calls his work, has made great progress......

Yes, there has been a lot of progress. Now, on the table is a piece of his work. Erya spent a lot of money to hire some of the best bronze craftsmen in the capital, cast a copper box larger than a palm with fine copper, and inlaid a transparent crystal on the surface of the box; Through the crystal mirror, a diamond-shaped needle made of magnet can be seen, pressing against an ivory seat and shaking tremblingly. This is the compass he designed. It's a pity that the cost is too high; Such a large piece of transparent natural crystal is so rare that it cost a total of 1,320 yuan even for polishing. And the cost of the entire compass is only 1,470.

In addition to the compass, he drew a map of the world marked with the warp and weft lines, which now hangs on one of the walls of his study. Of course, this map is very inaccurate, and if anyone wanted to rely on it for a voyage, it would undoubtedly be a complete adventure, and it would inevitably end in tragedy: all the islands, land, and coastlines were not where they were!

Although this world map has shortcomings of one kind or another, it is indisputable that it is indeed a world map. As soon as it was hung on the wall, countless records were set: the first original map of the world; the first map of the world using latitude and longitude; For the first time, it clearly depicts seven continents and five oceans...... Moreover, there is a blank space in the lower right corner of the map, indicating the creative collective of this map: Shang Cheng, Liu Yue, Huo Daya, Huo Erya, Yang Pan, as well as Sang Xiu and Zhennu Yiyi, who are making this map into an embroidery painting for better preservation. They were very happy to see their names on the map, as if they had done something very remarkable. In fact, this is quite remarkable! But for them, this is not at all commendable. As long as your name can be written on the same piece of paper as his, it will be far more important than a weird-looking map of the world.

Just now, Shang Cheng marked the distance between the north and south poles on the map based on the original data provided by Tian Xiu: 46,920 tangli.

Now, the problem of measuring latitude is solved, but this is only a small step forward in the development of navigation, and the problem of longitude needs to be solved next. Only when the problem of longitude is also solved can the big problems in navigation be truly solved, and the position of the sea can be determined one by one.

The principle of calculating the real-time longitude has been roughly recalled by Shang Cheng. As long as there is a wooden pole, and then the change of the sun shadow is marked in the sun, the minimum value is taken to determine the local noon time, and then compared with the time on the clock, calculate the time difference between the local noon and the prime meridian, which is of course the meridian where the Kamikyo Plain Prefecture is located, and then the distance between the local area and Kamikyo can be calculated. Combined with the latitude of the local area, it is natural to know the specific location of the local area. The problem was that he didn't have a clock that could keep time accurately; He didn't even have a clock, let alone how to make it, and he had no way to calculate the time difference, let alone the exact longitude......

As he walks around the room, he is recalling the principle of the clock, or looking for an alternative to the role of the clock. He remembered that there was a way. It seems to be a change in the stars or the trajectory of the moon or something. Another is to use a sextant to measure the relative position of the sea level and the stars, and then look for the corresponding data in the astronomical chart data, so that the longitude can be determined. However, he vaguely remembered that in addition to the sextant and the more advanced theodolite, there was also a more primitive measuring tool, a quadrator or a quintograph. He just couldn't think of it.

However, whether it is to make and use a sextant or to rely on the moon as a reference, a large amount of astronomical data is required. He began to think about whether to find a time to inquire about the Taishi Bureau and see if he could borrow or buy it from them. He further thought about whether it was necessary to tie up Li Dingyi first because of his bad reputation. With the presence of the former Shaoqing of the Taishi Bureau, maybe others won't let him eat a closed door, right?

When he was thinking nonsense, Sang Xiu gently buckled the door outside the door and said, "Lang Jun, the cicada girl is here." She says she has something to say to you. ”

Shang Cheng agreed and said, "I'll come." ”

Since Shang Cheng moved to this Zhuangzi, Cicada has often helped her father run errands, and invited Shang Cheng to come to her house from time to time. This girl is easy to get along with, and she doesn't have the arrogance of a big family at all, so she is very popular, not only in the same month, but also with Sang Xiu and Zhennu. When she saw Shang Cheng walk out of the door, she immediately nodded at him and said hello: "Brother Merchant." The tone of her voice and the demeanor on her face were very natural, casual and respectful, not at all inhibited, as if she was visiting relatives.

Shang Cheng joked: "Your father called you over again?" He just lost a good horse to me the day before yesterday, what do you want to lose today? ”

Cicada pursed her lips and smiled, "Then I don't know." He didn't tell me. She said quickly and quietly, "My father told me to give me a word: Don't go out lately; No matter who comes to visit, you can't be entertained! Don't forget! ”

Shang Cheng saw that she suddenly put her face up and spoke, the content was still so serious, he couldn't help but want to joke with her again, but when the words came to his mouth, he reacted and hurriedly asked, "Is something wrong?" ”

Seeing that Sang Xiu had already walked to the courtyard to see a few peach blossoms that had bloomed early, Cicada said, "Ganquan Palace." ”

She only said three words, but Shang Cheng immediately understood. The crown prince lives in Ganquan Palace! If the prince died, he should not be informed by Gu Shi; Since Gu Shi said not to go out recently, and he said so cautiously, there is no need to ask, it must be that the prince's poisoning has been exposed!

He nodded solemnly and said, "I see." You go back and tell your dad thank you. Gu Shi can remind him at this time, he is really grateful. If Gu Shi didn't try his best to stuff his daughter into him, he would really want to make this friend!

It's a pity that he wants to make friends, and he really wants to be an elder. There is always a contradiction between desire and reality......