How did Zhang Heng invent the seismograph?

While Cai Lun was studying how to improve papermaking methods, a young scientist in his twenties was engaged in another significant scientific research. He wants to explore the laws of celestial motion and earthquakes. This scientist is Zhang Heng.

Zhang Hengzi Hirako, a native of Nanyang (now Nanyang City, Henan Province), was born in poverty and lived with the help of relatives and friends. This harsh environment not only made Zhang Heng understand the hardships of working people's lives, but also prompted him to establish an ambition to study angrily. Zhang Heng is modest and eager to learn, and he can write good articles in his teens. After he entered imperial academy at the age of eighteen, he became a knowledgeable young scholar by familiarizing himself with the Four Books and Five Classics.

Although Zhang Heng has more knowledge than others, he is not proud at all, and he still learns from others' strengths with an open mind to further enrich his knowledge. Liu Zhao, the Emperor of the Han Dynasty, heard that Zhang Heng was knowledgeable and sent someone to ask him to be an official several times, but he didn't go. He often says to others: "One should not worry about his low status, but about his low moral quality;" One should not worry about getting too little in return, but about not having a wide range of knowledge. "Zhang Heng is most interested in studying mechanical, astronomical, calendar, mathematics and other natural sciences. In order to solve a problem, he made an instrument, and he often worked nonstop for several days until he succeeded. It is said that Zhang Heng made a flying bird out of wood. This wooden bird can hover in the air. As long as its wings droop, it will fly back to its original starting place. Unfortunately, this method of making wooden birds has not been passed down.

Liu Hu, the Emperor of Han Dynasty, heard that Zhang Heng was very learned, so he called him to the imperial court and put him in charge of the astronomical calendar.

After Zhang Heng wrote Taishiling, he made a musical instrument called Hunxiang because of his work needs.

Hunxiang is an astronomical instrument, which is used to observe stars, determine solar terms and understand other astronomical phenomena. It is an eight-foot-diameter hollow copper ball with an iron shaft inside, which is used to appreciate ancient landscape paintings. The direction in which the ball tilts on the shelf is exactly the direction of the earth's rotation axis. The surface of the copper ball is engraved with various important stars and scales, representing the operation of constellations and the astronomical phenomena in the sky. This elephant is connected to a machine with a set of gears, which is connected to leaky cauldron who tells the time. Leaky cauldron's dripping water can start the gear, and the gear will drive the elephant to rotate around the iron shaft once a day, which can accurately reflect the operation of the astronomical phenomena. After the elephant was made successfully, Zhang Heng sat in the room and looked at the instrument. Now a star rises in the east, a star rises in the middle of the sky and a star lands in the west. People went outside to look at the sky and found that the situation in the sky was basically the same as what Zhang Heng said. Facts have proved that the image number invented by Zhang Heng is a relatively accurate astronomical instrument in ancient times.

Then, Zhang Heng invented a seismograph to observe earthquakes.

During the Eastern Han Dynasty, earthquakes often occurred all over China. According to historical records, a major earthquake occurred in 23 years from the eighth year of Yong Yuan (AD 96) to the fourth year of Yan Guang (AD 125). In the first year of Jianguang in Andi (A.D. 12 1), a major earthquake occurred in September, affecting 35 counties. In some places, the earth cracked, and in some places, walls and houses collapsed, causing many casualties. In ancient times, most people were superstitious. When the earthquake happened, people thought it was a manifestation of ghosts and gods and were extremely afraid. Where there is an earthquake, the local officials should report it to Xiangjing City as soon as possible, and Taishiling will record it. If you are late, you will be convicted.

Scientist Zhang Heng is not superstitious about ghosts and gods. He believes that earthquakes are a natural disaster, and people should not only record earthquakes, but also study their laws. In order to fully grasp the earthquake information, he invented the seismograph in the first year of Shun Di Yangjia (AD 132). The seismograph is made of pure copper. It is eight feet in diameter and looks like a big jar. There is a protruding cover at the top that can be opened. Carved with patterns of mountain turtles, birds and animals as decoration. In the middle stands a pillar with a thick top and a thin bottom, next to the eight organs. Connected to the eight organs are eight dragons lying face down outside. Eight faucets are aimed at the east, northeast, north, northwest, west, southwest, south and southeast directions respectively. There is a copper ball in the mouth of each faucet. Under the eight faucets, there are eight bronze toads, with their heads held high and their mouths open. Where there is an earthquake, the pillar falls in the direction of the earthquake zone and touches the organ in that direction. Open the faucet connected to that organ, spit out the copper ball, and the copper ball will fall into the toad's mouth, giving a "clang" to inform the management. As long as the manager looks at which toad the copper ball fell into, he can know which direction the earthquake happened, so that he can report to the boss in time and send someone to know the situation quickly.

After the seismograph was successfully manufactured, it was placed in an earthquake observation room in Luoyang, the capital. One day, the faucet in the northwest suddenly opened its mouth and spit out copper balls. With a clang, the hammer ball fell into toad's mouth, indicating that there was an earthquake in the northwest. However, people living in Luoyang at that time did not feel the earthquake. In this way, people became suspicious, saying that Zhang Heng's invention was unreliable and the seismograph was not accurate. A few days later, Longxi (now Gansu Province) sent people to Luoyang, the capital, to report that an earthquake had occurred there a few days ago. When the date is checked, it happens to be the day when the faucet on the seismograph spits out the copper ball. Only then did people believe that the seismograph invented by Zhang Heng was accurate and reliable.

The seismograph invented by Zhang Heng is the first instrument to record earthquakes in the world. A similar instrument was made in Europe in A.D. 1880, more than 700 years later than Zhang Heng. It can be said that the seismograph invented by Zhang Heng is the beginning of observing earthquakes by scientific methods in human history and opens a new era of earthquake science.