The first person in the world to accurately measure the meridian length.
After the imperial edict was changed to calendar, a group organized and launched a large-scale astronomical geodesy. This survey completely negates the wrong theory of "the shadow of the sun is one inch, and the earth is thousands of miles away" with measured data, and provides quite accurate length of the first arc of the meridian of the earth.
The delegation initiated this large-scale astronomical survey for two main purposes. First, there was a traditional theory in ancient China: "An inch of the sun's shadow is a thousand miles away." According to the survey data in Jiaozhou (now Hanoi, Vietnam) at that time, He Chengtian, an astromathematician in Liu and Song Dynasties, began to doubt this, but it was not confirmed for a long time. Liu Zhuo, a mathematician in Sui Dynasty, put forward a concrete scheme, and denied this erroneous statement with the measurement results. He said: "The state of making love, there is no trace in the north, tens of thousands of miles, and there is a sun in the south, which is a thousand miles and an inch. It is really not bad." He suggested: "Please hire a water conservancy engineer and be a warlock. Take the land in Peiping, Henan, and you can measure hundreds of miles, so that the north and the south can make the right. When judging, if there is air leakage, level it with rope and divide it with air, which will be carried out on the same day. The difference rate can be known in the book. Then heaven and earth have nothing to hide, nothing to hide. It is shown to the saints in advance, and the effect is to eliminate doubts. " But this suggestion was not adopted in the Sui Dynasty. A survey line realized this plan. Secondly, at that time, it was found that the time of the solar eclipse and the eclipse it saw were different at different observation points, and the length of the solar shadow and the missing day and night minutes of each solar term were also different. This phenomenon was not taken into account in the past calendars. This requires field measurements in various places.
In this survey, Tai Shi Jian Nan Gong said that Tai Shi Guan Daxiang Yuan Tai and others went to various places to "wait for the shadow of the sun and repay Japan". And this line "is based on the contest between the north and the south, calculated by Pythagoras' method." It can be seen that the front line is not only responsible for organizing and leading the measurement work, but also personally undertaking the analysis and calculation of the measurement data.
At that time, the scope of investigation was very wide, from Tiele Uighur Department (southwest of Ulaanbaatar, Mongolia) at about 5 1 degree north latitude to Lin Yi (central Vietnam) at about 0/8 degree south latitude, which exceeded the land boundary between north and south of China. This scale is unprecedented in the history of world science.
Among them, the most noteworthy thing is that the survey team led by Nangong Said personally measured four points in the plain areas on both sides of the Yellow River according to Liu Zhuo's plan. From north to south, there are Baima in Huazhou (now hua county, Henan Province), Taiyuetai in Junyi, Bianzhou (now northwest of Kaifeng), Fugou in Xuzhou (now Fugou, Henan Province) and Wujin Pavilion in Shangcai, Yuzhou (now Shangcai, Henan Province). The white horse is in the north of the Yellow River, and the other three points are in the south of the Yellow River. They are all between east longitude 1 14.2 degrees-1 14.5 degrees, almost at the same longitude (that is, "north-south alignment" as Liu Zhuo said). There are 270 steps from Baima to Shangcai 526, and the height difference of the North Pole is 1.5 degrees. The conclusion is that there are about 80 steps in 35 1, and the height difference of the North Pole is 1 degree. This actually increased the length of the earth's meridian by one degree.
Because people have different views on the value of Tang ruler at present, the accuracy of this meridian measurement is limited. The preliminary estimation results show that the relative error between the measured value of a certain line and the modern value is about 1 1.8%.
Eratosthenes, an ancient Greek scientist, was the first to calculate the circumference of the earth according to the length of foreign sun shadows. Around 240 BC, he calculated the diameter of the earth in line of sight according to the different solar heights and trigonometry between Alexander and Aswan. Statia is a unit of length in ancient Greece, which varies from place to place. If calculated according to the length of Athens, the circumference of the earth is 46,620 kilometers, which is 16.3% more. If calculated according to the length of Egypt, the circumference of the earth is 39,690 kilometers, with an error of less than 2%.
The earliest meridian survey in the Islamic world was in 8 14 AD. Ninety years later, astronomer Alvara Mizi (about 783-850) took part in a geodetic survey of the Euphrates River plain. The calculation results show that the meridian is once 1 1 1.8638+.
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One line (683 ~ 727 AD) is the name of Buddhism. China was a famous astronomer and interpreter in the Tang Dynasty, whose real name was Zhang Sui, and he was born in Changle, Weizhou (now Nanle County, Henan Province).
His great-grandfather was a hero of Emperor Taizong's Xiangzhou viceroy and lord protector Zhang. His father Zhang is a county magistrate who is good at martial arts. The Zhang family had declined in the era of Wu Zetian. Zhang Sui lived in Guanzhong since he was a child and studied the calendar and the five elements of Yin and Yang. When he was young, he was famous for his extensive knowledge in Chang 'an. In order to avoid the entanglement of Wu Zetian's nephew, he was shaved as a monk and named as a monk. He studied Buddhist classics and astronomical mathematics in Songshan, Tiantai Mountain and Dangyang Mountain successively. He translated a variety of Indian Buddhist scriptures and later became the leader of Tantric Buddhism.
In the ninth year of the reign of Emperor Xuanzong of the Tang Dynasty (72 1 year), according to Li's Linde Calendar, several eclipses were not predicted, and Xuanzong ordered one party to preside over the revision of the new calendar. The most important achievement in his life is the compilation of Da Yan Li, which has made great contributions in making astronomical instruments, observing astronomical phenomena and presiding over astronomical geodesy.
When I was a child, my family was poor and I often got help from my neighbor, Grandma Wang. As a teacher of the son of heaven, our party often thinks of Grandma Wang. However, before I could repay her, Grandma Wang had come to see us. When her son * * committed a crime, Grandma Wang asked the parties to intercede. A line understands what * * wants, and the national law is difficult to violate. He said: grandma is a benefactor in the business, and she should be satisfied with how much money and things she wants, but she can't do it in this business. Grandma Wang cursed the defeated party for ingratitude. Line can only keep apologizing in front of grandma. After seeing grandma leave, the client handed a cloth bag to two confidants and told them to hide in the designated place. He said that seven things would enter the bag from noon to dusk. They did so and brought back seven pigs in cloth bags. A group of people put seven pigs in the prepared big urn and covered them. Early the next morning, people in the palace knocked on the door eagerly, saying that the emperor had something to discuss. Li Longji just met him in the toilet hall and asked, "The Big Dipper disappeared last night. Is this a good thing or a bad thing?" ? How to deal with it? The lines made a well-founded analysis, and then put forward "Mo Ruo amnesty the world". Li Longji immediately wrote a letter to Amnesty International. That night, one of the seven stars appeared in the sky, and seven days later, all seven stars appeared in the sky ... The benefactor's son committed a capital crime, and he must repay his kindness without violating the national laws. In this case, he had to use his own "method". Duan described what happened, but he also had a knot in his heart: it was strange, but it spread widely and had to be written.
Monks and his party knew the Expo like the back of their hands, and they were especially good at counting. The hooks were hidden deep. Scholars at that time could not measure them. When I was a child, my family was poor, and my neighbor was Wang Lao. I helped hundreds of thousands of people before and after, and a group of Kaiyuan Zhong inherited an experience of mutual respect. I've been thinking. Looking for Wang Er, who has committed the crime of * * and is not in prison, Lao Mei visited the party for help and said, "Lao Mei wants gold and silks and rewards him tenfold. It's hard to ask if Mingjun enforces the law. How? " Wang Lao Ji cursed with his hand: "How do you know this monk?" A line of thanks, regardless of the ending. A group of hundreds of workers in Huntian Temple were scheming, but they were ordered to leave the room empty, move a big urn to the middle, secretly select two permanent slaves and give them cloth bags. They said, "There is an abandoned garden in the corner of a square, so you wait in the middle. From noon to dusk, when something comes in. The number 7 can be completely hidden. Lost a staff member. " The slaves said they would leave, and when they arrived, if there were groups of slaves, they would go home. He was overjoyed, so he put it in an urn, covered it with a wooden cover, and sealed it in the mud on June 1 ST, engraved in Sanskrit and inscrutable. In court, the ambassador knocked at the door and called urgently. When they arrived in the toilet hall, Xuanzong greeted them and asked, "The Grand Master played something last night, but Beidou didn't show up. What is this, Xiang Ye? " The client said: "In the post-Wei period, I was blind. So far, the emperor's car has disappeared. There is nothing in the past, and heaven will warn your majesty. If I see it, I will forgive the world. " Xuanzong followed. Also, at night, a surname fights Beidou, once in see you on monday, once every seven days. It's strange for Shi Cheng to talk about this matter, but it has spread widely and has to be written down.
According to Ming Zhengde's Annals of Daming Prefecture and this edition of Annals of Nanle County, Lechang County is located in the Western Han Dynasty and belongs to the eastern county. Lechang County was abandoned in the early Eastern Han Dynasty. In the Western Jin Dynasty, it was renamed Changle in the original Lechang County, which belonged to Wei County. In the third year of Emperor Kai of Sui Dynasty (AD 583), Fanshui County was set up in the northwest of Changle County, belonging to Weizhou. In the first year of Daye (AD 605), Changle County was merged into Fanshui County. In the 16th year of Zhenguan in Tang Dynasty (AD 643), Fanshui County was changed to Changle County. In the second year of Zhenming in the Five Dynasties (AD 9 16), Changle County was renamed Nanle County, which still belongs to Weizhou. Check Weizhou again, formerly known as Wei Jun, changed in the Northern Zhou Dynasty, and renamed Xingtang House, Guangjin House and Daming House in the Five Dynasties. From the Five Dynasties to the early Republic of China, Nanle County was under the jurisdiction of Daming House for a long time. As can be seen from the above, Nanle County evolved from Lechang, Changle and Fanshui, and Weizhou Fanshui and Changle in the Tang Dynasty are now Nanle County in Henan Province.