Han Qian slept until three o'clock in the morning, and for the first time since leaving Jinling, his tense nerves were completely relaxed. He slept extremely comfortably, and woke up full of energy and high spirits.
He knew in his heart that his father should be doing official business in the front office at this time, so he didn't want to rush to the front office directly. After washing, he ate two meat buns and took a Shi Gong punch, sweating gurglingly.
He took the sweat towel from Zhao Ting'er's hand and was wiping his sweat when he saw Gao Shao leading people to empty out a side room on the east side, and then imprisoned Mrs. Xi in it.
They even went to the state prison early in the morning, borrowed a few pairs of shackles, and used one of them to cuff Mrs. Xi's feet without tying her up tightly.
Gao Shao and others have all seen Mrs. Xi's nimbleness like a civet cat. At this time, they only need to cuff her legs to restrict her movements and prevent her from coming into contact with swords and sharp weapons. The threat she poses will be greatly weakened.
.
Mrs. Xi's strength cannot be compared with Gao Shao, Tian Cheng and other masters who practice hard every day and work hard on their bodies.
Han Qian walked into the side room and stared at Mrs. Xi with interest, thinking about how to train her. At this time, Han Laoshan walked in and told Han Qian that he would serve as a hostage in Jingyun Village for four days.
Some changes in Qianyang City.
Han Daoxun has sent Zhao Kuo as the leader to purge the jailer team.
This time, those who plan to stay in Xuzhou with Han Daoxun include Han Laoshan, Fan Xicheng, Zhao Kuo and other eleven old servants of the family soldiers, their wives and children, and thirteen children of the family soldiers who have been strictly trained by Han Qian for more than half a year.
In the state prison, in addition to the warden, clerk, and scribes, several prison chiefs with native origins were also purged in the name of "sacrifice in the line of duty."
There are more than fifty jailers left. Although they are both Han Chinese and natives, it is currently confirmed that they are not controlled by the four surnames. Basically, their families are in the city. Zhao Kuo leads ten of his family soldiers to form the jailer team.
, and can almost completely control this team of jailers.
In addition, there are more than a dozen family soldiers led by Han Laoshan and Fan Xicheng in Furong Garden. The children of the family soldiers are responsible for basic defense and assisting Han Daoxun in handling official affairs.
The four surnames have also allowed some of their disciples to return to the state camp, but only a small part. At present, it can only keep the state camp from being dispersed, and it is not enough to pose a big threat.
"...Except for the fact that Yang Qin took the young master back to Qianyang and Guo Nuer took some Zuosi scouts to guard the garden, the master saw that the situation in the city was not so urgent. Yesterday, he ordered Lin Zongjing to take some of the scouts out.
Qianyang City, we went to survey the surrounding terrain map." Han Laoshan told Han Qian the general situation in the city.
Han Qian nodded, indicating that he understood everything.
More than 700 years ago, Pei Xiu of the Western Jin Dynasty proposed six methods of cartography, using the six principles of division, accuracy, road, high and low, square and straight, to calculate specific geographical information and draw it into topographic maps.
Han Qian's early training of his family soldiers was mainly to strengthen anti-reconnaissance, lurking, and survival skills in the wild. After Xinchanghou Mansion and Wanhonglou made it clear that he planned to establish Secret Cao Zuosi, he used the drawing of field terrain maps as a way to cultivate scouts and reconnaissance.
A core subject of ability, the scouts affiliated with Zuo Si are required to use all their time to study, master it as quickly as possible, and put it into practice.
The so-called spying on the enemy's situation, in Han Qian's view, the most core information almost includes geography and terrain information, which will also greatly improve the accuracy of spying on the enemy's situation.
Just like this, the requirements for Zuosi's scouts are bound to be extremely high. At present, only the early family soldiers have some basic surveying and mapping methods, while the newly recruited scouts are somewhat miserable.
Although it is said that Xuzhou was founded six to seven hundred years ago, the topographic map of Xuzhou currently preserved by the Yamen is extremely rudimentary.
In the past hundred years, the central government's control over remote states and counties has been greatly weakened by the separatist rule of Tibetan towns. Topographic maps are almost no longer updated, and many places have changed beyond recognition.
Therefore, Lin Zongjing took his people out of the city to collect, survey and map the geographical information of Qianyang, Langxi, and Tanyang counties, and compiled it into an atlas. This was not only to use the precious time when the situation had eased to conduct arduous training, but also to prepare his father for true mastery in the future.
The situation in Xuzhou laid the foundation.
If Han Daoxun couldn't even figure out Xuzhou's mountains, forests, rivers, remote terrain, and the distribution of native and guest households, how could he possibly control the overall situation in Xuzhou?
Thinking that Guo Nuer and the others had already mastered the six traditional cartographic methods, Han Qian did not need to worry about normal surveying and mapping operations.
However, Han Qian also knew that the traditional six methods of cartography had too many flaws and were far from accurate.
Not to mention establishing complete latitude and longitude coordinates, even the elevation and mileage of mountains and rivers cannot be measured accurately.
The problem is that the person in the dream, Zhai Xinping, only has concepts such as longitude and latitude lines in his mind. Han Qian is also at a loss as to how to determine and measure the longitude and latitude lines.
Han Qian touched his chin, forgetting to tease Mrs. Xi, and stood at the door of the room, thinking that the study of trigonometry based on the Pythagorean theorem had been quite thorough in this world, and the values of trigonometric functions could be calculated relatively easily.
You can make simple goniometers and altimeters.
There are goniometers that can theoretically measure the height difference of the sun in different areas. As long as you accept the concept that the earth is a sphere, you should be able to determine the latitude based on current knowledge, right?
However, measuring longitude requires knowing the precise time difference between two places, which is much more difficult.
Han Qian thought for a long time, thinking that before the invention of accurate clocks, an accurate time reference system could only be established based on the specific positions of the stars and the moon on the sky. However, the trajectories of the stars and the moon are very complicated. Even if an observatory is established to conduct
, it may take decades to accurately observe and determine the specific trajectory of the stars and the moon, and use this as a precise time reference.
Han Qian thought for a long time and did not feel that measuring longitude was something he was capable of at this time. However, even determining the longitude at this time could greatly improve the accuracy of contemporary maps.
At this time, it was impossible and completely incapable of Han Qian to organize a large number of manpower to carry out actual measurements in various places. However, records of Gui's observation of the sun can be found in the documents preserved by the previous dynasty. This is actually to determine the latitude of various places.
The specific data required.
In different areas, as long as they are located at the same latitude, the relative length of the solar shadow at the same time is the same.
The place where the sundial has no shadow on the summer solstice is the Tropic of Cancer. This is a fact that has been confirmed by astronomical and calendar experts thousands of years ago.
The failure to form a complete concept of latitude and even extend it to map surveying is mainly due to the lack of a clearer understanding of the land where we live.
"Sir, what are you thinking about, standing here in a daze for so long?" Zhao Ting'er waited for a long time and couldn't help but push Han Qian's shoulder and asked.
Han Qian knew that the whole work would be very complicated if it went forward. He wanted to be lazy and could only leave the matter to Zhao Ting'er. He immediately told Zhao Ting'er some of the principles involved and asked her to help read the information and collect data.
Perform calculations.
After they have calculated the latitudes of different areas and sent people to select a few places for verification, they can officially start correcting the Dachu map.
"The earth under our feet extends straight and vast in all directions, how could it be round?" Zhao Ting'er asked doubtfully. She already knew the calculations of triangular intercepts and other methods, but she couldn't accept that the earth is spherical.
concept.
Seeing Zhao Ting'er asking this, Han Qian was also slightly startled. Could he say that people in later generations can fly into space and see that the terrain is round?
Han Qian thought about it for a while and said to Zhao Ting'er:
"Huainanzi Tianwen Xun compiled by Liu An of the Western Han Dynasty wrote, 'If you want to know the height of the sky, the tree surface is one foot high, and the north and south are thousands of miles apart. If you measure the yin on the same day, the north surface is two feet, and the south surface is nine inches, which is thousands of miles south.
The numbers "Yin is short of an inch" and "A thousand miles is short of an inch" are also expressed in the "Zhou Bi Suan Jing", but these were calculated by the predecessors based on the assumption that the earth is flat and extended. And the monks of the previous dynasty calendars
Yi Xing, Nangong Shuo and others organized people to conduct on-site measurements and confirmed that the inferred conclusion of "a thousand miles is as short as an inch" has a huge error. This can also be found with specific measured data, which many people find difficult to understand. You can find Monk Yi Xing
Based on the actual measured data, we can then use the algorithm recorded in "Zhoubi Suanjing" or "Huainanzi" to back-reference and see if it is consistent only if we assume that the earth is a sphere?"
"Qingyun, Qingyun!" Zhao Ting'er saw Qingyun passing by inside and outside the yard, and hurriedly called to her, wanting to ask her to go to the study to search for the measured data of the sundial. Zhao Ting'er thought that the head of the family, Han Daoxun, was on his way to Xuzhou to take up a post.
What he carries the most is the various books he has collected over the years. He should be able to find some actual measurement data of sundials.
However, just as Zhao Ting'er was about to pull Qingyun out, she saw Han Daoxun rushing back from outside accompanied by Fan Xicheng. He stuck out his tongue, saluted, and then retreated behind Han Qian.
Han Daoxun glanced at Mrs. Xi in the locked room and didn't ask any questions. He smiled and asked the two maids Zhao Ting'er and Qingyun: "Why are you two little girls running around so recklessly?"
"Young Master must say that the earth is round. Ting'er wants to drag Qingyun to the study to search for actual measurement data of sundials from different places to prove that Young Master is just bluffing Ting'er." Zhao Ting'er said.
Han Daoxun thought carefully about the calculation method that Han Qian told Zhao Ting'er, and said: "This calculation is very complicated. Don't be busy doing it. Keep it in your mind and wait until you return to Jinling. The goniometer you mentioned is best able to
Before leaving Xuzhou, build one and keep it!"
Making a goniometer for land use is not complicated, but to ensure that the instrument's scale is accurate, it cannot be completely left to the craftsmen below. Han Daoxun still hopes that Han Qian can personally supervise the construction.
Hearing a "crash" sound behind him, Han Qian turned around and glanced at Mrs. Xi who was standing stubbornly in the corner. It was she who moved her body and moved the shackle chain. Her eyes were full of confusion, as if she was thinking about what he had just said to Zhao Ting'er.
Those words he said made him smile in his heart. Apart from his father, there were really few people in the world who could understand what he and Zhao Ting'er said.
Fan Xicheng was confused after hearing this.
"Mrs. Xi thinks that my father's plan to build a goniometer is a grotesque skill, so she looks disdainful?" Han Qian said with a smile, "The goniometer can be built to measure the specific height of a mountain.
After measuring the height of a mountain, in turn, the relative height and height of the terrain around the mountain can be calculated. This is also necessary for digging canals, building water conservancy, and irrigating farmland in the mountainous areas of Xuzhou.
Means——Mrs. Xi, but you still think that my father and son are just trying to gather money?"
"Mrs. Xi?" Han Daoxun looked at the beautiful female prisoner doubtfully and asked Han Qian.
"She was Feng Changyu's concubine. His brother pretended to be Feng Xuan's subordinate and watched our movements all the way. I was fooled by that - when I was in Jingyun Village, she came over to assassinate me. Feng Changyu finally handed her over for disposal.
" Han Qian said.
"The crime is pitiful, so don't commit murder indiscriminately." Han Daoxun said as he did not want Han Qian to be too murderous.
"She knows too many secrets. If I really want to let her go, Feng Changyu won't let her go," Han Qian said. "But if she can stay on her own and not cause any trouble, I can let her wear ankle braces."
Activities in this yard, helping Ting'er with some things."
Having said this, Han Qian looked towards Mrs. Xi.
Now no one wants the fragile balance between Qianyang City and the Four Surnames to be broken, and the Four Surnames themselves never want it to be broken. Han Qian thought that if Mrs. Xi was really released, Feng Changyu would imprison her if he didn't kill her.
From the moment she was abandoned by Feng Changyu, Xi Rong knew that what Han Qian said was true, and no matter what, even if it was for the convenience of escaping in the future, or even if she continued to find opportunities to assassinate Han Qian, the thief, she could gain a certain limit at this time.
Freedom is also extremely important. She lowered her head and expressed her submission in front of Han Qian for the first time.
Fan Xicheng felt that it was too dangerous to let the captured assassin move around in his living area, even if he was wearing ankle braces. However, when the head of the family glanced at the female assassin and seemed to have no objection, he did not say anything.