Su Song (1020–1101 AD) was a renowned Han Chinese polymath who was described as a statesman, astronomer, cartographer, horologist, pharmacologist, mineralogist, zoologist, botanist, mechanical and architectural engineer, poet, antiquarian, and ambassador of the Song Dynasty (960–1279).
Su Song was the engineer of a hydro-mechanical astronomical clock tower in medieval Kaifeng, which employed the use of an early escapement mechanism.The escapement mechanism of Su's clock tower had been invented by Buddhist monk Yi Xing and government official Liang Lingzan in 725 AD to operate a water-powered armillary sphere, although Su's armillary sphere was the first to be provided with a mechanical clock drive.Su's clock tower also featured the oldest known endless power-transmitting chain drive, called the tian ti (??), or "celestial ladder", as depicted in his horological treatise.The clock tower had 133 different clock jacks to indicate and sound the hours.Su Song's treatise about the clock tower, Xinyi Xiangfayao (?????), has survived since its written form in 1092 and official printed publication in 1094. The book has been analyzed by many historians, such as Joseph Needham. The clock itself, however, was dismantled by the invading Jurchen army in AD 1127, and although attempts were made to reassemble it, the tower was never successfully reinstated.
The Xinyi Xiangfayao was Su's best-known treatise, but the polymath compiled other works as well. He completed a large celestial atlas of several star maps, several terrestrial maps, as well as a treatise on pharmacology. The latter discussed related subjects on mineralogy, zoology, botany, and metallurgy.
European Jesuit visitors to China like Matteo Ricci and Nicolas Trigault briefly wrote about Chinese clocks with wheel drives,but others mistakenly believed that the Chinese had never advanced beyond the stage of the clepsydra, incense clock, and sundial.They thought that advanced mechanical clockworks were new to China and that these mechanisms were something valuable that Europeans could offer to the Chinese.Although not as prominent as in the Song period, contemporary Chinese texts of the Ming Dynasty (1368–1644) described a relatively unbroken history of mechanical clocks in China, from the 13th century to the 16th.
Life and works
Career as a scholar-official
Su Song was born in modern-day Fujian, near medieval Quanzhou.Like a contemporary, Shen Kuo (1031–1095), Su Song was a polymath, a person whose expertise spans a significant number of different interests. It was written by his junior colleague and Hanlin scholar Ye Mengde (1077–1148)that in Su's youth, he mastered the provincial exams and rose to the top of the examination list for writing the best essay on general principles and structure of the Chinese calendar.From an early age, his interests in astronomy and calendrical science led him onto a distinguished path as a state bureaucrat. In his spare time he was fond of writing poetry, which he used to praise the works of artists such as the painter Li Gonglin (1049–1106).He also was an antiquarian and collector of old artworks from previous dynasties.
In matters of administrative government, he had attained the rank of Ambassador and President of the Ministry of Personnel at the capital of Kaifeng, and was known also as an expert in administration and finance.After serving in the Ministry of Personnel, he became a Minister of Justice in 1086.He was appointed as a distinguished editor for the Academy of Scholarly Worthies, where in 1063 he edited, redacted, commented on, and added a preface for the classic work Huainanzi of the Han Dynasty (202 BC–220 AD).Eventually, Su rose to the post of Vice President of the Chancellery Secretariat. Among many honorable positions and titles conferred upon him, Su Song was also one of the 'Deputy Tutors of the Heir Apparent'. At court, he chose to distance himself from the political rivalries of the Conservatives, led by Prime Minister Sima Guang (1019–1086), and the Reformists, led by Prime Minister Wang Anshi (1021–1086); although many of his associates were of the Conservative faction.In 1077 he was dispatched on a diplomatic mission to the Liao Dynasty of the Khitan people to the north,sharing ideas about calendrical science, as the Liao state had created its own calendar in 994 AD.In a finding that reportedly embarrassed the court, Su Song acknowledged to the emperor that the calendar of the Khitan people was in fact a bit more accurate than their own, resulting in the fining and punishment of officials in the Bureau of Astronomy and Calendar.Su was supposed to travel north to Liao and arrive promptly for a birthday celebration and feast on a day which coincided with the winter solstice of the Song calendar, but was actually a day behind the Liao calendar.Historian Liu Heping states that Emperor Zhezong of Song sponsored Su Song's clocktower in 1086 in order to compete with the Liao for "scientific and national superiority."In 1081, the court instructed Su Song to compile into a book the diplomatic history of Song-Liao relations, an elaborate task that, once complete, filled 200 volumes.With his extensive knowledge of cartography, Su Song was able to settle a heated border dispute between the Song and Liao dynasties.
Transmission of Su's text and his legacy
When Su Song's Xinyi Xiangfayao was written in 1092 and the horological monograph finalized and presented in 1094, his work was published and widely printed in the north. In the south, printing and circulation of his work was not widely distributed until Shi Yuanzhi of Jiangsu had it printed there in 1172.
When presenting his clocktower design to the Emperor Zhezong, Su Song equated the constant flow of water with the continuous movements of the heavens, the latter of which symbolized the unceasing power of the emperor.This appealed to emperor, who featured artwork representing the clocktower on vehicles of major imperial processions, as illustrated in the Illustration of the Imperial Grand Carriage Procession of 1053.
The later Ming Dynasty/Qing Dynasty scholar Qian Zeng (1629–1699) held an old volume of Su's work, which he faithfully reproduced in a newly printed edition. He took special care in avoiding any rewording or inconsistencies with the original text as well.Again, it was later reprinted by Zhang Xizu (1799–1844).
Interestingly enough, Su Song's treatise on astronomical clockwork was not the only one made in China during his day, as the Song Shi (compiled in 1345) records the written treatise of the Shuiyunhun Tianjiyao written by Juan Taifa. However, this treatise no longer survives.
In the realm of modern research, the late British biochemist and historian of Chinese science Joseph Needham (1900–1995) (known as Li Yuese in China) did extensive research and analysis of Su Song's texts and various achievements in his Science and Civilization in China book series. Joseph Needham also related many detailed passages from Su's contemporary medieval Chinese sources on the life of Su and his achievements known in his day. In 1956, John Christiansen reconstructed a model of Su Song's clocktower in a famous drawing, which garnered attention in the West towards 11th-century Chinese engineering.A miniature model of Su Song's clock was reconstructed by John Cambridge and is now on display at the National Science Museum at South Kensington, London.In China, the clocktower was reconstructed to one-fifth its actual scale by Wang Zhenduo, who worked for the Chinese Historical Museum in Beijing in the 1950s.