Chinese Science 13 (1996): 55-81

The Use of the Twenty-eight Xiu as a Day-Count in Early China

Marc Kalinowski

[Marc Kalinowski is professor of Chinese religion and thought at the Ecole Pratique des Hautes Etudes. He is the coordinator of the Mengxi bitan ~ ~ ¥ ~ translation project in Paris, and is now preparing a book on the formation of Chinese calendrical astrology. Among his publications are "Mythe, cosmogonie et theogonie dans la Chine ancienne," L'Homme 127-1 (1996), Cosmologie et divination dans la Chine ancienne (Paris, 1991), and "La litterature divinatoire dans le Daozang, "Cahiers d'Extreme-Asie, vol. 5 (1989-1990).]

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he origin of the twenty-eight celestial lodges (xiu fED in China remains to Tthis day a much debated issue. The first complete list of these constella­ tions surrounding the sky may be dated from the second half of the fifth century B.C. 1 In the astrocalendrical texts of the late Warring States (480-222 B.C.) and the Former Han (206 B.C.-8 A.O.) periods, the Chinese sidereal zodiac takes its definite shape as an equatorial belt divided into 365.25 degrees (du m'.) grouped in twenty-eight unequally spaced "lodges." Each lodge is defined by a determinative star (juxing We£) which indicates its first degree (chudu Wm'.). 2 The zodiacal position of a given celestial body is noted by the name of the lodge in which it stands and, eventually, the degree it has reached within this

1 See the representation of the sky with names of the twenty-eight lodges inscribed on a lacquerware object found in 1978 in the tomb of the Marquis of Zeng; Wang Jian­ min, Liang Zhu and Wang Shengli, "Zeng hou Yi mu chutu de ershiba xiu qinglong baihu tubiao" [The twenty-eight lodges, Green Dragon and White Tiger design in the tomb of the Marquis Yi of Zeng], Wenwu no. 7 ( 1979), pp. 40-45. 2 For a general presentation of the system of the xiu, see Joseph Needham, Science and Civilisation in China, vol. 3 (Cambridge: Cambridge Univ. Press, 1959), pp. 229- 59; and Chen Zungui, Zhongguo tianwenxue shi [A history of Chinese astronomy] (Shanghai: Renmin chubanshe, 1982), pp. 305-84. 55 56 Chinese Science 13 (1996) lodge. Thus, in Han times, the sun was to be found at the winter solstice be­ tween the end of Dou8 and the beginning of Niu9• Fifteen days later, it had moved by fifteen du eastwards, reaching the eighth du in Nii 10 • The same obser­ vation could be repeated every fifteen days, all along the twenty-four divisions of the solar year. 3 Owing to the phenomenon of the precession of equinoxes, the sidereal zodiac shifts westwards slightly every year. For example, the winter solstice moved from Niu9 to Dou8 around Han times. It was still in Dou8 during the Tang dynasty ( 618-907) and is now in Jir Thus, all the calendrical treatises in the official histories contain a table giving the sidereal position of the sun for the twenty-four solar periods (Jieqi fri~). An important function of these tables was to regulate the adjustment of the twelve lunar months (12 x 29.5 = 354 days) to the tropical year (365.25 days). According to the lunar-solar standard of the Chinese calendar, the lunation con­ taining the winter solstice was counted as the eleventh month of the year, that containing the spring equinox was the second month of the year, that containing the summer solstice was the fifth month of the year, and that containing the autumn equinox was the eighth month of the year. Thus, since the sun was standing in Dou8 at the winter solstice in Han times, lodge Dou8 was defined as the "solar station" (richan B li/1) of the eleventh month. This applied also to other months of the year, each of which was attached to a specific solar station (or lodge).4 Strangely enough, Han calendrical literature has no table giving sidereal lo­ cations for the moon. Though the length of the sidereal month (27.3 days) was well known, the texts simply mention that the moon moves thirteen degrees eastwards every day without assigning any sidereal location for its daily move­ ment.

3 To facilitate the identification of the lodges, we have added to their names numbers as subscripts indicating their positions within the series (Jiao,, Kang,, ... , Zhen,.). The first complete list of zodiacal positions of the sun for the twenty-four solar periods is found in the Three Revolutions Calendar by Liu Xin (c. 32 B.c.-23 A.O.). According to Liu Xin's system, the solar station for the winter solstice was Dou, (12th du), the solar station for the spring equinox was Lou 16 (4th du), the solar station for the summer solstice was Jing,, (31st du) and the solar station for the autumn equinox was Jiao 1 (10th du); see Hanshu, "Li.ilizhi 2," in Lidai tianwen liili dengzhi huibian [A comprehensive collection of the treatises on astronomy and calendar-making in Official Histories] (Beijing: Zhonghua shuju, 1976), pp. 1431-32. For the zodiacal position of the winter solstice during the Han dynasty and its variation in later times, see Li Jiandeng, "Suicha zai woguo de faxian, ceding he lidai dongzhi suozai de kaozheng" [A study of the evolution of the winter solstice position in relation with the discovery and calculation of the pre­ cession of equinoxes], Zhongguo tianwenxue shi wenji vol. 3 (1984), pp. 124-37. 4 The keying of the twelve lunations to the twenty-four solar periods is described in the Hanshu ("Li.ilizhi 2," Dengzhi huibian, p. 1409). For the role played by solar stations in Chinese astronomy, see Chen Zungui, Zhongguo tianwenxue shi, pp. 722-24.