Chongzhen lishu 崇禎曆書

Chongzhen lishu 崇禎曆書 is a collection of data and texts compiled during the Chongzhen reign-era 崇禎 (1628-1644) in the Ming period 明 (1368-1644), aimed at reforming the calendar. It introduced classical European astronomical knowledge from various aspects. The entire work consists of 46 texts with a total length of 137 juan (including one star chart and one celestial sphere). The compilation was managed by a specially established Bureau of Calendars (liju 曆局). The chief editor of the work was Xu Guangqi 徐光啟 (1562-1633), and after his death, Li Tianjing 李天經 (1579-1659) took over. The work at the calendar revision lasted from 1629 to 1634. The Jesuit missionaries who participated in translating European astronomical knowledge included Johann Adam Schall von Bell (Ch. Tang Ruowang 湯若望; 1591-1666) and Giacomo Rho (Ch. Luo Yagu 羅雅谷; 1593-1638). Before them, others such as Johannes Schreck (Ch. Deng Yuhan 鄧玉函; 1576-1630) and Niccolò Longobardo (Ch. Long Huamin 龍華民; 1559-1655) had briefly worked on the project.

The Chongzhen lishu includes five main categories: the basic theory of astronomy, astronomical tables, necessary mathematical knowledge (mainly planar [pingmian sanjiaoxue 平面三角學] and spherical trigonometry [qiumian sanjiaoxue 球面三角學] and geometry [jihexue 幾何學]), astronomical instruments, and conversion tables for traditional and Western measurement units. Since the chief editor, Xu Guangqi, emphasized basing the calendar calculations on an understanding of the principles of astronomical phenomena, the theoretical section occupies one-third of the entire book.

The Chongzhen lishu adopts the celestial system and geometric calculation methods developed by Tycho Brahe (1546-1601). Its advantages include the introduction of clear concepts of Earth and geographical latitude and longitude, as well as important astronomical concepts such as spherical astronomy (qiumian tianwenxue 球面天文學, parallax (shicha 視差), atmospheric refraction (daqi zheshe 大氣折射), and the related correction calculation methods. It also adopted several commonly used Western measurement units: one full circle of the sky is divided into 360°; one day and night is divided into 96 parts (quarters of an hour), with 24 hours; and degrees and hours below these are calculated using a sexagesimal system.

However, due to political complications at the end of the Ming period, the Chongzhen lishu was not used for calendar compilation after its completion. After the Qing dynasty 清 (1644-1911) was established, Johann Adam Schall von Bell revised the Chongzhen lishu into 103 juan, and along with the newly compiled version of the calendar, presented it to the Qing government, which issued it. The new calendar was named the Shixian li 時憲曆. The revised book Chongzhen lishu was renamed the Xiyang xinfa lishu 西洋新法曆書 "Western new method calendar book". The 100-juan edition of this book, included in the series Siku quanshu 四庫全書 was renamed Xiyang xinfa suanshu 西洋新法算書 in order to avoid the taboo word of the Qianlong Emperor's 乾隆帝 (r. 1735-1796) personal name, Hongli 弘曆.