Zhang Heng (78 ~ 139), a native of Nanyang (now Shiqiao, Nanyang, Henan), was a famous astronomer and mathematician in Han Dynasty. He was born in a broken bureaucratic family. He studied hard since he was a child and was very literary.

1994 16-year-old Zhang Heng left his hometown to study abroad and went to imperial academy, the highest institution of learning at that time. At that time, Baode, the magistrate of Nanyang County, appreciated Zhang Heng's talent very much and invited him to be the monarch's book of Nanyang County to help him deal with the county administration. Zhang Heng assisted Baode in managing Nanyang and achieved remarkable results. Eight years later, Baode was transferred to the capital and Zhang Heng resigned to live at home. During his stay in Nanyang, he devoted himself to astronomy, Yin and Yang, calendar calculation and so on, and repeatedly studied Xuan Jing by Yang Xiong in the Western Han Dynasty. 1 1 1 year, Zhang Heng was called to Beijing and became a doctor.

1 18 years, Zhang Heng was appointed as a businessman. In the second year, it was promoted to Taishiling. Zhang Heng worked in the position of Taishiling for 14 years, and many of his major scientific research work was completed at this stage. 133, Zhang Heng was promoted to an assistant middle school. But it was soon excluded and vilified by eunuchs. Three years later, Zhang Heng was transferred to Beijing as the prime minister of Hejian Wang. But Liu is an arrogant and extravagant person who does not abide by the central code. After Zhang Heng took office, he was strict in law and discipline and cracked down on the strongmen, which made everyone respect him. Three years later, he wrote to Shun Di asking for retirement, but the court made him an official. It was in this year (139) that he passed away.

Zhang Heng made outstanding contributions in astronomy, seismology, mechanical technology, mathematics and even literature and art all his life. He is a rare and versatile scientist.