Zhang Heng has been an official for six years in a row. In the first year of Andi Jianxing (A.D. 12 1), he was transferred to Sima Ling, the public transport department. The official office of the bus Sima Ling is located next to the south gate of the palace. Its duty is to defend the emperor's palace, enter and leave the memorial inside and outside, accept tributes from officials and people all over the country, and receive people from all over Beijing. The transfer of scientist Zhang Heng to this position fully shows how the feudal emperor did not attach importance to science and did not give talented people the opportunity to give full play to their talents. However, it is in this position that Zhang Heng still uses all possible time and energy to continue his academic research. Besides astronomy, he also made great efforts in mathematics, physics and mechanical manufacturing. We mentioned Zhang Heng's famous mathematical work "The Theory of Calculation" and the design of a drum car and a tour guide car. It is the result of painstaking research by Zhang Heng when he took office as bus conductor.
In the first year of Shun Di Yongjian (AD 126), Zhang Heng was transferred to Taishiling. This is Zhang Heng's second official order. At that time, some people who were keen on fame and fortune took the opportunity to laugh at Zhang Heng's "but before he could conquer, he was dead" and failed to get promoted. They satirized his bad career and said that "it is not an enterprising trend to come back after five years as a historian". It was a tired bird returning to its nest and attacking Zhang Heng for being "unique and narcissistic". Some people regard the scientific instruments created by Zhang Heng as "the art of killing dragons" and as a road to "artistic success". Some people also laughed at Zhang Heng's "unfairness" and thought that if Zhang Heng had focused on being an official, he would have been promoted. Faced with the cold shoulder of the ruling class and the cynicism of the traditional forces, Zhang Heng wrote an article called "Ying Jian" to answer the ridicule of these short-sighted people who "carve a boat for a sword and wait for a rabbit".
In the English Sword, Zhang Heng not only clearly shows his confidence and determination in his research, but also shows his modest attitude of "not being ashamed of his partner, but being ashamed of his wisdom". At the same time, I also said that I don't want to compete with those who are greedy for fame and fortune and short-sighted. I insist on the broad mind of "making friends by making use of the past".
In addition to the armillary sphere, another immortal invention of Zhang Heng in the history of world science, the seismograph, was successfully developed during his second Taishiling. The seismograph was invented in 132 (the first year of Yangjia) and is the first instrument in the world to measure earthquakes and their directions. The invention of seismograph has written a glorious page in the history of human struggle against earthquakes, and since then, the history of human observation of earthquakes with instruments has begun.
China is a country with frequent earthquakes. For thousands of years, our ancestors have been stubbornly fighting against earthquake disasters. As early as 3800 years ago, there were records about earthquakes in China. According to the chronicles of bamboo books unearthed in Jin Dynasty, Yu Shun's "fissure spring" may refer to an earthquake; The most explicit report is the "Taishan Earthquake" in the 7th year of Xia Dynasty (about 1590 BC), which is the earliest earthquake record in the world. The earthquake scene at the turn of October reported in The Book of Songs Xiaoya said: "Leaves (meaning fire pole) shake the electricity, but they are uneasy (meaning unseasonable and disturbing), rivers are boiling, and hills (hilltops) are ■ (that is, broken). According to textual research, this is a vivid record of the landslide caused by the Shaanxi earthquake in the late Zhou Dynasty (780 BC) (the first two sentences may be the earthquake precursor of the combination of "earth sound" and "earth light"); In the third century BC, Lu's Spring and Autumn Annals recorded that "the country was founded for 8 years (BC 1 177), and in June, King Wen was ill for 5 days, but the ground moved east, west, north and south, and he did not go abroad. "This record clearly points out the time and scope of the earthquake, and it is the earliest concrete and reliable record in China earthquake records. In addition, there are also records about earthquakes in the pre-Qin ancient books such as Chunqiu, Guoyu and Zuozhuan, and many ancient earthquake records have been preserved. Since the Western Han Dynasty, earthquakes have been recorded as disasters in the historical "Five Elements Records" of various dynasties.
During the Eastern Han Dynasty, earthquakes occurred frequently in China. According to the Records of Five Elements in the History of the Later Han Dynasty, there were 26 * * * earthquakes in the thirty years from the 4th year of Yonghe (AD 92) to the 4th year of Andi Yan Guang (AD 125). In the sixth year of Emperor Han 'an (A.D. 1 19), two major earthquakes occurred. The first time happened in February, Luoyang, the capital, and 42 other counties and countries were affected. In some places, the ground cracked, in some places, the ground flooded, and in some places, houses on the city walls collapsed, killing and injuring many people. The second time was in winter, the earthquake spread to eight counties and vast areas of the country, causing huge losses of life and property. At that time, due to the lack of scientific knowledge, people were extremely afraid of earthquakes and thought they were dominated by gods.
Zhang Heng worked as an official in Luoyang at that time, and had a lot of personal experience about those earthquakes. Zhang Heng witnessed the tragic situation after the earthquake many times and was deeply saddened. In order to master the national earthquake dynamics, he recorded earthquake reports in various places. On the basis of existing astronomy, after years of unremitting exploration and research, he finally invented the world's first seismograph to determine the direction of earthquakes at the age of 50 (AD 132).
According to Zhang Heng, the seismograph is made of bronze and looks like a wine bottle with a diameter of 8 feet. There is a raised cover on the top of the instrument, and the surface of the instrument is engraved with various patterns such as seal script, mountains and rivers, turtles, birds and animals. There are eight dragons around the instrument, and the faucets are arranged in eight directions: east, south, west, north, northeast, southeast, northwest and southwest. Every dragon has a copper ball in its mouth. There is a bronze toad crouching under each faucet. Toad aimed at the dragon's mouth and opened it as if waiting to swallow food. No matter where there is an earthquake, the copper ball in the dragon's mouth will roll out and fall into the toad's mouth below, making a stirring noise. People who keep the seismograph can know the time and direction of the earthquake when they hear the sound. Check the seismograph to see which direction the Longkou copper ball spits. On the one hand, it can record accurate seismic data; At the same time, we can also find the affected areas along the direction of the earthquake and do some rescue work to reduce losses.
On February 3rd, A.D. 138, the longkou of the seismograph placed in Luoyang, the capital, suddenly opened, and a copper ball spit out from the longkou and fell into toad's mouth. But at that time, people in Luoyang, the capital city, felt little about the earthquake, so people talked about it one after another and suspected that the seismograph was not effective. Those bureaucratic scholars who don't believe in Zhang Heng are bragging when attacking Zhang Heng. However, every few days, a flying horse came to Longxi (now the southeast of Gansu Province) and reported a sudden earthquake a few days ago. Therefore, people are "convinced" of the seismograph created by Zhang Heng. Longxi is more than 0/000 Li away from Luoyang/kloc-,and the seismograph marks correctly, which shows that its seismic sensitivity is quite high. According to the analysis of Luoyang people who didn't feel the earthquake recorded in Zhang Hengchuan, the lowest earthquake resolution detected by seismograph is about 3 degrees (according to China's earthquake intensity scale 12 degrees), which can be said to be a very great achievement under the technical conditions of 1800 years ago.
Zhang Heng's seismograph was successfully manufactured, and the first scientific instrument to record earthquakes appeared in history. Abroad, it took more than a thousand years, and it was not until the 3rd century A.D./KLOC-0 that similar instruments appeared at the Malaha Observatory in ancient Persia. The earliest seismograph in Europe also appeared 1700 years after its invention.
However, because the feudal rulers always paid little attention to scientific and technological inventions, Zhang Heng's research and inventions in earthquakes could not get their support. After the seismograph was made, it was not widely used, and even the seismograph itself did not know when it was destroyed. This is really a great loss in the history of science and technology.
Unfortunately, the internal structure principle of Zhang Heng's seismograph is very brief in the history books, which makes people unable to understand it in detail. After Zhang Heng, several scientists in the history of our country have made special research on seismographs. For example, in the Northern and Southern Dynasties, people in Hejian (now Hejian County, Hebei Province) thought that Du Fang had painted the structures of exquisite instruments such as Huntian, Bifurcation, Ground Motion, Wu Tong, Leaked Carving and Hou Feng. With pictures, mathematical calculation and text description, these materials are compiled into a scientific and technological masterpiece called "Qi Zhun". In the early years of Sui Dynasty, Lin also wrote a Bronze Classics of Seismology, expounding the mechanical principle of seismographs. But these important works have not been handed down. Modern Chinese and foreign scientists have done a lot of research work and put forward some restoration schemes. During the period of 1959, Zhang Heng's seismograph model restored by Wang Zhenduo was exhibited in the China History Museum. However, there are still discrepancies between Wang Zhenduo's model and the records in Zhang Hengchuan of the Later Han Dynasty.
Although the concrete structure of the internal machinery of Zhang Heng Seismograph has long been lost, it is a scientific and technological worker in China in recent years. Using modern scientific knowledge, according to the relevant records of Zhang Hengchuan in the later Han Dynasty and referring to archaeological data, after various explorations, they finally reached the mechanism and principle of the seismograph made by Zhang Heng more than 800 years ago, and designed the imaginary map of this instrument.
The seismograph contained in "Zhang Hengchuan in the Later Han Dynasty" is the main structure of the seismograph. After repeated research by many scholars, the basic structure of Zhang Heng's seismograph conforms to the principles of physics. Like modern seismograph, it uses the inertia of object mechanics to pick up ground motion waves, so as to carry out long-distance measurement. This principle has been used to this day. Mr. Wang Zhenduo correctly summed up that this musical instrument consists of two parts: one part is a heavy copper column standing in the center of the bottle-shaped part of the musical instrument. The bottom of the copper column is pointed and the top is upward, which is equivalent to a pendulum indicating inertial motion. Zhang Heng called it "Zi Zhu"; The other part is eight groups of lever machinery in eight directions (that is, eight poles are connected around the "bucket bead" and extend in all directions), which are directly connected with eight faucets. These eight poles are the "Eight Roads" in Zhang Hengchuan's book in the later Han Dynasty, which is also the "Bending Transverse" in mechanics today. These two parts are located in the center of a closed copper instrument. However, due to its thick top and thin bottom, high center of gravity and small supporting surface, Duzhu is like an inverted tumbler, so it is extremely vulnerable to vibration, even if it is weak. When an earthquake occurs, the instrument body vibrates, and only the "single column" tilts because of its own inertia moving relative to the instrument body, losing balance, pushing a group of levers to open the dragon mouth associated with the outside of the instrument body, spitting out copper balls and falling into the mouth of the toad below, and reporting the earthquake and recording the earthquake direction through the sound of shooting down and the falling direction of the copper balls.
The seismograph designed by Zhang Heng is also the image embodiment of his materialistic view of nature. The seismograph is oval with the same diameter as an elephant, symbolizing the sky mentioned by Huntian. The flat bottom of an instrument with capital letters represents the earth, which is located in the sky. The mountains, turtles, birds and beasts carved on the vessel symbolize mountains, dragons, white tigers, larks and basalt. Eight diagrams and seal scripts such as Gan, Kun, Zhen, Xun, Kan, Li, Gen and Dui represent the spirit in all directions. Eight dragons symbolize yang on the top and toad symbolizes yin on the bottom, which constitutes the dialectical relationship between yin and yang, up and down, and motion and static. The capital is listed in an indomitable position and arranged according to the ancient saying of "Tianzhu". The mechanism naturally adopts lever structure.
This great invention of Zhang Heng not only embodies the wisdom and creative spirit of scientists, but also reflects the advanced scientific and cultural level of China in the Eastern Han Dynasty, which makes us feel extremely proud.
In addition to the seismograph, Zhang Heng also created another meteorological instrument, which is the meteorological instrument. Many people used to think that "meteorometer" and "seismograph" were the same instrument. According to recent research by scientists, this view is wrong. In the later Han Dynasty, Zhang Hengchuan's phrase "Yang Jia Yuan nian, after the wind and the seismograph were rebuilt" means that Zhang Heng created both the wind and the seismograph. However, the structure of this meteorological instrument is not recorded in Zhang Hengchuan. Now let's introduce something about the weather meter.
Mr. Zhu Kezhen wrote in the article "China's Past Meteorological Achievements": "In terms of meteorological instruments, the rain gauge and the weather vane were both invented by China, much earlier than the western countries. Zhang Hengchuan of the later Han Dynasty:' In the first year of Yangjia, the seismograph was rebuilt after the wind.' The Book of the Later Han Dynasty only talked about the structure of the seismograph, but not a word about what the meteorological instrument looked like, so some people suspected that the meteorological instrument and the seismograph were a kind of instrument, but they were not. Three Auxiliary Huang Tu was written by people in the later Han or Wei and Jin Dynasties. The book says: "There is a Lingtai in the south of Chang 'an Palace, which is 15 meters high and has an armillary sphere made by Zhang Heng;" There is also a kind of wind and copper, which moves when it meets the wind. Obviously, it is said that wind is another musical instrument, and its compilation method is not recorded in detail in Hanshu, but according to the book Watching Elephants and Playing Zhan, "Every wind must be in a high place. Set up a 5-foot pole, make a plate on the pole, make three feet on the pole, two feet stand outside, tie one foot to turn inside, turn when the wind comes, turn around, put the flowers in your mouth and spend them. In other words, we can know that Zhang Heng's Waiting for the Wind and the Wind Chicken on the West Roof are similar. Waiting chickens in the west began to be recorded in books in the12nd century, which was later than that recorded by Zhang Heng 1000. "
In addition to Mr. Zhu Kezhen's argument, there are three other materials about meteorological meters. (1) There are 42 officials who belong to Taishiling in the Book of the Later Han Dynasty Guan Bai, among whom 3 are in charge of "waiting for the wind". It can be seen that it is within Zhang Heng's duty to make a meteorological instrument and observe the weather. (2) Miscellanies of Xijing contains an item "Emperor's guard of honor and harmony with the wind". It can be inferred that the instrument "Xiangfengwu" can be installed not only on the platform, but also on the vehicle. The invention of the weather meter may have preceded Zhang Heng. Although the meteorometer made by Zhang Heng has been improved, it is not a particularly outstanding new invention, so I won't repeat it in historical records. (3) Earthquake, weather and Wu Tong are listed as three items in the new book "Qi Zhun" written by the Northern Wei Dynasty; There is no word "waiting for the wind" in Lin's Jing of Shock Copper in Sui Dynasty. Therefore, on the one hand, we can infer that the structures of these two objects may not be exactly the same; On the other hand, it can also be considered that seismographs and meteorologists are two completely different instruments.
To be sure, in addition to the seismograph, Zhang Heng also invented the meteorological instrument. Through these discussions, we can also get a glimpse of the creation and application of meteorological instruments in Han Dynasty. At the same time, it also proves that Zhang Heng is a great pioneer in the history of science in China. He is serious and responsible for his post, can combine reality in scientific research, and is good at learning the scientific experience of predecessors and making innovations and improvements.