Zhang Heng (Chinese: 張衡; AD 78–139), formerly romanized Chang Heng, was a Chinese polymathic scientist and statesman who lived during the Eastern Han dynasty.
Čang Cheng (čínsky pchin-jinem Zhāng Héng, znaky zjednodušené 张衡, tradiční 張衡; 78 v Nan-jangu – 139 v Luo-jangu) byl čínský astronom, matematik, vynálezce, geograf, kartograf, básník, politik a učenec.
Zhang Heng was a Chinese mathematician, astronomer, and geographer. His seismoscope for registering earthquakes was apparently cylindrical in shape, with eight dragons’ heads arranged around its upper circumference, each with a ball in its…
Although ZhangHeng understood that the sun, moon and planets move in circles, he lacked a model for a logically structured theory and so could not establish a corresponding astronomical theory.