Zhang Heng(78~139), whose courtesy name was Pingzi, was a famous astronomer in the Eastern Han Dynasty.
张衡(78~139 ), 字平子。东汉天文学家。历官郎中、太史令等。
His publication Ling Xian (Mystical Laws) summarized his achievements in astronomy.
《灵宪》一文，全面地体现了他在天文学上的成就。
He held that the universe was infinite in both space and time and invented the world's first eauatorial armillary sphere.
他提出“浑天说”，认为宇宙在空间上没有边界，在时间上没有起点。他创造的天文仪器浑天仪，是一种演示天体星象运动的表演仪器。
He also believed that the heaven was round and the earth flat.
关于地球的结构，他持“天圆地平”说。
Furthermore, he recorded 2 500 stars, drew the first comprehensive star chart and accurately interpreted the formation of lunar eclipses.
他还记录了2500颗恒星，画出了中国第一张完备的星图，正确解释了月食的成因。
He was renowned as the inventor of the world's first seismograph, which was invented 1 800 years earlier than other similar devices.
在地震学上，他发明了候风地动仪，是世界上的地震仪之祖，比其它类似设备早了1800年。
Legend said that he invented two magical devices:a three-wheeled device that could rotate automatically and a wood carving that could fly in the sky.
传说他当时还制作过两件神奇的器物，一件是有三个轮子的机械，可以自转;一件是一只木雕，能在天上飞翔。
In a mathematical treatise, he approximated pi by working out two numbers.
在数学上，他写过《算罔论》一书，推知圆周率大约在3. 14和3. 16之间。
He held fast the principle of seeking truth from facts and strongly objected to the non-scientific viewpoints in the society.
他坚持实事求是的原则，坚决与鄙弃知识的社会愚昧思想作斗争。
Zhang Heng was also an outstanding writer, whose Er Jing Fu (Two Capital Cities) and Gui Tian Fu (To Live in Seclusion) are considered as literary masterpieces in ancient China.
张衡还是一位大文学家，有《二京赋》、《归田赋》等传世之作。
。