Zu Chongzhi 祖冲之

A versatile scientist renowned at home and abroad


Chinese Name: 祖冲之

English Name: Zu Chongzhi

Other Names: Zu Wenyuan 祖文远

Born: 429

Died: 500


Water Dull Mill 水碓磨

Guide Car 指南车

Thousand Mile Boat 千里船

Timer 定时器

Pi 圆周率

Main Works:

Da Ming Calendar 《大明历》

Zu Chongzhi 祖冲之
Zu Chongzhi 祖冲之

Brief Biography of Zu Chongzhi

Zu Chongzhi was an outstanding mathematician and astronomer in the Northern and Southern Dynasties.

Zu Chongzhi (429-500 years), courtesy name Wenyuan 文远, was born in Jiankang County 建康县, Danyang County 丹阳郡 (now Nanjing 南京, Jiangsu Province 江苏省), and his native place is Qiu County 遒县, Fanyang County 范阳郡 (now Laishui County 涞水县, Hebei Province 河北省).

Born in the family of Zu in Fanyang 范阳, he devoted his whole life to natural science, and his main contributions were in mathematics, astronomy and calendar, and mechanical manufacturing. On the basis of exploring the precise method of pi initiated by Liu Hui 刘徽, he first calculated pi to the seventh decimal place, that is, between 3.1415926 and 3.1415927. His “ancestral ratio” has made great contributions to mathematical research. It was not until the 16th century that Arab mathematician Al Qasi broke this record.

Liu Hui 刘徽

The Daming Calendar 《大明历》, written by him, was the most scientific and progressive calendar at that time, providing a correct method for astronomical research in later generations. His main works include An Bian Lun 《安边论》, Conjugation 《缀术》, Shuyi Ji 《述异记》, Li Yi 《历议》, etc.

Personal Life and Major Contributions

Family background

From the end of the Western Jin Dynasty to the Sixteen Kingdoms Period, large-scale wars broke out in the north. Zu Chongzhi’s ancestors migrated from Fanyang County (now Laishui County, Hebei Province) to Jiankang (now Nanjing, Jiangsu Province), the capital of the Eastern Jin Dynasty. Zu Chongzhi was born in Jiankang. His grandfather, Zuchang 祖昌, served as the chief craftsman of the Liu Song Dynasty. He was an official of the imperial court in charge of civil engineering. His father, Zu Shuozhi 祖朔之, served as a “request to the imperial court”. He was knowledgeable and often invited to attend royal ceremonies and banquets.

Zu Chongzhi received a good family education from an early age. His grandfather told him about the “changes of the stars”. His father led him to read the scriptures and classics. His family’s influence and his diligence made him interested in natural science, literature, philosophy, especially astronomy, and he had a reputation for erudition in his youth.

The statue of Zu Chongzhi 祖冲之塑像
The statue of Zu Chongzhi 祖冲之塑像

Due to Zu Chongzhi’s reputation of being erudite and versatile, he was sent by Emperor Xiaowu of the Southern Song Dynasty to the academic research institution of the imperial court at that time to do research work, and later to work in the General Mingguan 总明观. At that time, General Mingguan 总明观 was the highest scientific research institution in China, equivalent to the ancient Chinese Academy of Sciences.

In the General Mingguan 总明观, there are five disciplines, namely, literature 文, history 史, Confucianism 儒, Taoism 道, and Yin and Yang 阴阳. The system of teaching in different disciplines is implemented. Famous scholars from all over the country are invited to teach. Zu Chongzhi is one of them. Here, Zu Chongzhi had access to a large number of national books, including astronomy, calendar, and calculation, and had the prerequisite to learn from and expand.

Devote himself to science

In the fifth year of Daming (461), Zu Chongzhi served as an official in the governor’s office of Southern Xuzhou (now Zhenjiang 镇江, Jiangsu 江苏). During this period, Zu Chongzhi continued his academic research and made great achievements, although his life was very unstable.

In the sixth year of Daming (462), Zu Chongzhi sent the carefully compiled “Da Ming Calendar 大明历” to Emperor Xiaowu of the Song Dynasty for promulgation and implementation. Emperor Xiaowu of the Song Dynasty ordered officials who knew the calendar to discuss the advantages and disadvantages of this calendar. Finally, Emperor Xiaowu of the Song Dynasty decided to change to the new calendar in the ninth year of Daming (465).

Commemoration for future generations 后世纪念
Commemoration for future generations 后世纪念

In the eighth year of Daming (464), Zu Chongzhi was transferred to Lou County 娄县 (now the northeast of Kunshan County 昆山县, Jiangsu Province 江苏省) as the county magistrate. Later, he went to Jiankang (now Nanjing 南京, Jiangsu Province) to serve as an official of the audience. From then on, until the early years of the Qi in the Southern Dynasty, he spent a lot of energy on studying mechanical manufacturing, recreating the guide car driven by copper parts, inventing a “thousand-mile boat” that can travel hundreds of miles a day, a “wooden ox and a flowing horse”, a water mill (a tool for processing grain by water), and designing and manufacturing leaky pots (ancient timers) and clever insinuators.

A Pioneer in the History of Mathematics — Pi

Zu Chongzhi calculated that the true value of pi is between 3.1415926 and 3.1415927, which is equivalent to the seventh decimal place, simplified to 3.1415926. Therefore, Zu Chongzhi was selected as the world’s first scientist by the World Records Association to calculate pi to the seventh decimal place.

Pi 圆周率
Pi 圆周率

Zu Chongzhi also gave two fractional forms of pi: 22/7 (approximate rate) and 355/113 (density rate), where the density rate is accurate to the seventh decimal place. Zu Chongzhi’s accurate calculation of pi is a great contribution to China and even the world. Later generations named the “accurate calculation” “Zu Chongzhi’s pi” after him.

Video: Zu Chongzhi & Pi — Chinese Science and Technology

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