19세기 조선의 曆算 매뉴얼 『推步捷例』

Abstract

Chubo-cheoprye (推步捷例, A Handy Example of Calendrical Calculation), written by Nam Byeong-gil (南秉吉, 1820-1869) a leading astronomer and mathematician in 19th century Korea, can be called “a handy manual for calendar making calculation.” Two types of orbital models for calculation of celestial bodies’ position, one of Tycho Brahe’s(1546-1601) for five planets and the other of Kepler’s(1571-1630) elliptic orbital model for the Sun, the Moon and eclipses occurred by the combinatorial motion of the two, were adopted in Korean calenderical calculation system in 1726 and in 1742 respectively. Chiljeong-chubo (七政推步, Calendrial Calcuation of Seven Celestial Bodies) compiled in 1798 was the first systemized manual of calendrical calculation adopting the two types of methods above in a single book. By the mid 19th century though, the manual Chiljeong-chubo had decayed and astronomers were wanting a new one, and Nam, widely reorganizing the contents of the old book, revised some calculation procedures and reedited a part provided for putting fortune notes (yeokju 曆注) in the annual calendar, titled jakryeoksik (作曆式, calendar making method). Chubo-cheoprye published in 1861 is very peculiar in its writing style that gives only calculation procedures with elementary operations step by step to the reader and never provide with theoretical explanation on the astronomical meaning of any calculation. This is why it is called “a handy manual of calendrical calculation.” Nam did not forget to give a caution to the expecting users of the manual, technicians of calendar making calculation in the royal astronomical bureau (觀象監). If they enjoy only the handy manual of calculation, they would be foolish on theoretical understanding of astronomy before long. It may be the reason why he, a year before writing Chubo-cheoprye, had written a handbook, titled Siheon-giyo (時憲紀要 Concise of Western Calendar, 1860), for the theoretical discussion.