What three things did Zhang Heng invent in his life?

The seismograph is a masterpiece created by Zhang Heng, a scientist of the Eastern Han Dynasty in China. During the Eastern Han Dynasty when Zhang Heng lived, earthquakes were frequent. Zhang Heng has a lot of personal experience about earthquakes. In order to master the national earthquake dynamics, after years of research, he finally invented the Hou Feng seismograph in the first year of Yangjia (AD 132), which was also the first seismograph in the world.

The seismograph has eight directions. There is a dragon ball in the mouth of each direction, and there is a toad under each faucet. If there is an earthquake on both sides, the dragon ball in the longkou in that direction will fall into the toad's mouth, so that the direction of the earthquake can be measured.

2. Improved armillary sphere

On the basis of the armillary sphere invented by Geng Shouchang in the Western Han Dynasty, Zhang Heng created a more accurate and comprehensive armillary sphere according to his own armillary sphere theory.

The leaky astrolabe is a water-borne elephant. Use a copper ball with a diameter of more than four feet, which is engraved with 28 nights, Chinese and foreign officials, yellow equator, north and south poles, 24 solar terms, constant display circle and constant hidden circle to form an elephant, and then use a set of rotating machinery to combine the elephant with the clepsydra.

The elephant is controlled by running water from a leaky kettle to make it rotate synchronously with the celestial sphere, thus showing the Sunday visual movement of the starry sky, such as the appearance of stars and the transit of the sun. It also has a subsidiary organization called Ruilun Cai Ming, which is a mechanical calendar, connected with elephants by transmission devices. From the beginning of each month, a leaf is born every day; Drop a leaf every day after half a month. Among them, the second-class clepsydra used is the earliest known record of the second-class clepsydra.

3. Compass car

The compass made by Zhang Heng is composed of two-wheeled unicycle by using mechanical principle and gear transmission. The trunk adopts a gear system with automatic clutch, and a woodcut fairy is placed on the upper layer of the trunk shell. No matter which direction the car rotates, the woodcut fairy's outstretched arm points south.

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Zhang Heng made outstanding contributions to the development of astronomy, mechanical technology and seismology in China, and invented the armillary sphere and seismograph, which was one of the representatives of the theory of armillary sphere in the middle Eastern Han Dynasty.

Known as the "wood saint" by later generations. Because of his outstanding contribution, the United Nations Astronomical Organization named a crater on the back of the moon as "Zhangheng Crater" and the asteroid 1802 in the solar system as "Zhanghengxing". Later, in memory of Zhang Heng, Zhang Heng Museum was built in Nanyang.

Reference: Zhang Heng (a famous astronomer in the Eastern Han Dynasty) _ Baidu Encyclopedia