Chapter 60 Section 11 "Chongzhen Calendar" and "Shixian Calendar"

The calendar "Da Tong Li" used in the Ming Dynasty is essentially the continuation of the "Shou Shi Calendar" in the Yuan Dynasty. It has been in use for a long time, and there are already big errors.Although some people have suggested changing the calendar from time to time, it has not been implemented.In May Yiyoushuo (June 21, 1629 A.D.) solar eclipse in the second year of Chongzhen, Qin Tianjian's forecast based on the "Da Tong Li" had obvious errors, while Xu Guangqi's calculation based on Western astronomical methods was quite accurate. So the Ming court decided that Xu Guangqi would be responsible for changing the calendar.

The Calendar Bureau established by Xu Guangqi was assisted by Li Zhizao and Li Tianjing, and hired Jesuits N. Longobardi, D. Pantoja, S. de Ursis, E. Diaz ), Aleni (J.Aleni), Deng Yuhan (J.Terrenze), Tang Ruowang (JASvon Bell) participated in the compilation work.The whole work was completed from the second year of Chongzhen to the seventh year of Chongzhen (AD 1634), and the results were concentrated in the "Chongzhen Almanac" and various memorials written for the reform of the calendar.Xu Guangqi was in charge of the editor-in-chief of "Chongzhen Almanac". After his death in 1633, Li Tianjing was in charge.

"Chongzhen Almanac" includes 46 kinds and 137 volumes.The whole book is divided into six chapters and five basic chapters. The former divides the calendar into six parts: the sun, the moon, the sun and the moon, the five latitudes, and the five stars. theory), method (astronomical tables), method (mathematical knowledge necessary for astronomical calculations, mainly trigonometry and geometry), magic instrument (measuring instruments and calculation tools) and Huitong (various Chinese and Western units of measurement conversion table) and other five aspects.Among them, "Fayuan" has more than 40 volumes, which is the core of the book. It not only discusses the problems of the calendar itself, but also focuses on astronomical theories and calculation methods.

This is a relatively comprehensive and systematic introduction to European astronomy knowledge.The book cites a large number of materials in Copernicus' "On the Movement of Celestial Spheres", basically translated eight chapters of it, and translated 17 of the 27 observation records published by Copernicus.The book introduces Galileo's observations about the movement of sunspots on the solar surface.The book quotes several passages from Kepler's "On the Motion of Mars".These were the latest achievements of European astronomy at that time.At the same time, the book clearly introduces the concept of the earth, introduces latitude and longitude and their measurement and calculation methods.When estimating the apparent positions of the sun, moon, and five stars, etc., the numerical correction methods of the parallax of the sun and the difference of air are introduced.In terms of computational methods, spherical and planar trigonometry are introduced.In terms of coordinate systems, the ecliptic coordinate system is introduced.

However, due to religious standpoint, the book adopts the cosmic system of the Danish astronomer Tycho, who believes that the earth is the center of the universe, the sun, moon and stars revolve around the earth, and the five planets revolve around the sun, without introducing Copernicus’s Heliocentric theory.When explaining the apparent motion of the sun, the moon, and the five stars, a set of small wheel systems such as the epicycle and the deferent are used, without introducing the three laws of planetary motion of the German astronomer Kepler.Regarding Copernicus' heliocentric theory and Kepler's law of motion, it was not until 1760 when P. Michael Benoist, a French Jesuit, presented the world map "Kunyu Quantu" to Emperor Qianlong, that they were mentioned in the explanatory text To be introduced, and introduced into China.

After the "Chongzhen Almanac" was compiled, due to the obstruction of the opposition and the war at the end of the Ming Dynasty, it was not officially promulgated in the end of the Ming Dynasty. After the Qing army entered Beijing in 1644, Tang Ruowang deleted and revised the "Chongzhen Almanac", compressed it into 103 volumes, renamed it "Western New French Almanac", and presented it to the Qing court.The Qing court adopted it, and named the calendar compiled based on it "Shixian Calendar" and promulgated it.Tang Ruowang was also appointed as the supervisor of Qin Tianjian, becoming the first foreigner to preside over the astronomy and calendar in China.