Seismograph Seismograph is another masterpiece handed down from ancient times by Zhang Heng, a scientist in Han Dynasty. In the Eastern Han Dynasty, where the opening arm was located, earthquakes were quite frequent. According to the 0.5-line Testament of Historical Records of the Eastern Han Dynasty, there were 26 major earthquakes in the 30-odd years from the first year of Yong 'an (AD 92) to the fourth year of Emperor Yan Guang of the Han Dynasty (AD 125). Earthquake countries are sometimes as large as dozens of counties, resulting in ground fissures and landslides, flooding of rivers and collapse of houses, causing a lot of losses. Zhang Heng has many personal experiences about earthquakes. In order to understand the national earthquake dynamics, he finally invented the seismograph in the first year of Zhengjia (AD 132)-the first seismograph in the world.

Seismograph is another masterpiece handed down from ancient times by Zhang Heng, a scientist in Han Dynasty. During the Eastern Han Dynasty when Zhang Heng lived, earthquakes were frequent. According to the Records of Five Elements in the History of the Later Han Dynasty, there were 26 major earthquakes in the thirty years from the 4th year of Yonghe (AD 92) to the 4th year of Andi Yan Guang (AD 125). Earthquake areas sometimes reach dozens of counties, causing ground fissures and landslides, rivers flooding, houses collapsing and huge losses. Zhang Heng has many personal experiences about earthquakes. In order to master the national earthquake dynamics, after years of research, he finally invented the seismograph in the first year of Yangjia (AD 132)-the first seismograph in the world.

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