Lecture 15

Dunhuang Studies and the History of Science and Technology

The manuscripts found in the Dunhuang library cave also include some valuable texts related to science and technology. Especially numerous of these are writings of pragmatic nature such as medical works, prescrip- tions, arithmetic manuals, calendars. Below I will briefly describe some of the main texts related to science and technology, and point out their value from the point of view of the history of science.

1. Astronomy

The observation of stars is the foundation of astronomy, and since the multitude of stars in the sky seemed so mysterious for people of the past, astronomy and astrology mixed together in every ancient civiliza- tion, developing early on and with time forming an increasingly complex system. Ancient Chinese astronomy existed as a field of knowledge since the early Warring States period. Each of the three early astrologers, Gan De 甘德, Shi Shen 石申 and Wu Xian 巫咸, recorded the results of his celestial observations, drew a star map and added divination texts, hand- ing these down to posterity. At the end of the Three Kingdoms period, Chen Zhuo 陳卓, the grand astrologer of the Eastern Wu 東吳 state sum- marized the results of Gan De, Shi Shen and Wu Xian and incorporated these in his own book. Regrettably both Chen Zhuo’s work and the writ- ings of the three ancient astrologers were subsequently lost. We are for- tunate to have discovered among the Dunhuang manuscripts a fragment of an astrology manual (Xingzhanshu 星占書; P.2512) written in 621. This records 283 inner and outer constellations and 1,464 stars identified by Gan De, Shi Shen and Wu Xian, which matches precisely the number of stars of the three astrologers recorded by Chen Zhuo, as it appears in the astronomical chapters of the Jinshu 晉書 and Suishu 隋書, both compiled in the early Tang. A comparison with the Kaiyuan zhanjing 開元占經 shows that both texts have omissions and should be used together to complement one another. At the same time, the Jinshu and Suishu merge the stars of the three astrologers; the Kaiyuan zhanjing mainly 414 lecture 15 presents Shi Shen’s data, whereas the Dunhuang Xingzhanshu differen- tiates between the stars of the three astrologers, using red ink to write those of Shi Shen, black for Gan De and yellow for Wu Xian. This format shows that the Xingzhanshu is an earlier work than the three other Tang works on astrology mentioned above. After the enumeration of constella- tions there are 11 divination-type comments, which must have come from Chen Zhuo’s work. This book is extremely useful for understanding the contemporary level of Chinese astronomy. On the same scroll, before the stars of the three astrologers, there is a text called Ershiba xiu ciwei jing 二 十八宿次位經, which records information on the twenty-eight constel- lations, and is earlier than Li Chunfeng’s 李淳風 treatise that appears in the astronomical chapter of the Jinshu. In addition, the same scroll also has a pentasyllabic poem Xuanxiang shi 玄象詩 which uses a popular format to describe the course of the stars, demonstrating that during the early Tang astronomical knowledge was widely spread among the general population. Another discovery relevant to the above Xingzhanshu was that of an early Tang star chart (S.3326). On the basis of the treatises and charts of Gan De, Shi Shen and Wu Xian, the chart depicted 1,348 stars and used three different colors to distinguish between the stars and constellations of the three astrologers. The twelve starting and ending positions closely match those of Chen Zhuo (as recorded in the Jinshu), showing that these positions are also based on the star charts of the three astrologers. The star chart in S.3326 is divided into twelve sections along the celestial equa- tor, according to the sequence of the sun’s location in each of the twelve months. The stars south of Ziweiyuan 紫微垣 are drawn using cylindrical projection, whereas Ziweiyuan is drawn on a planar projection chart with the North Star in its center (Fig. 15.1). The accompanying explanations are identical with those in Lu Chunfeng’s Yisizhan 乙巳占 and Qutan Xida’s 瞿曇悉達 Kaiyuan zhanjing, showing that they all derive from the same source. According to historians of science, this is the earliest ancient star chart in the world, and also has the highest number of stars. It has attracted the interest of specialists both in China and abroad, and Joseph Needham drew attention to its significance by publishing a photograph in the volume dealing with astronomy in his Science and Civilization in China series.1 He also dated the manuscript of the star chart to 940. In contrast,

1 Joseph Needham and Ling Wang, Science and Civilization in China, Vol. 3: Mathematics and the Sciences of the Heavens and Earth, Cambridge: Cambridge University Press, 1959, p. 277.