| Research Abstract |
1.We classified patterns of calculation of the winter or summer solstice in Shou Shi Li, the last method of establishing the calendar before the Ming dynasty in China, and made a strict interpretation of the original text on the basis of this classification. Some parts of the text have ambiguous expressions and we cannot interpret them when we only consider each phrase in question. Our approach is valid for this question. We can determine the interpretations of paragraphs 3-6 about the winter solstice in 1277, paragraphs 3-10 about summer solstice and paragraph 3 about winter solstice in 1278, and paragraphs 3, 5-7, 11, and 13 about winter solstice in 1279.
2.Zu Chongzhi(429-500)computed the time of a tropical year from three data of measuring shadow length. This method, the Zu Chongzhi's method, was very popular in Chinese astronomy, Wang Xun, Guo Shoujing used this method and computed the time span of one tropical year, 365.2425 days. Zu supposed that the function of shadow length was symmetry and computed the ratio of changing shadow length. Historians of astronomy in modern Japanese called the Zu's method to the "incline method" because Zu supposed that the ratio of changing shadow length was the liner. However there were some historical materials in China that this method was named the Zu's method. And Huang Ding also described this method, Zu Chongzhi method, in the "Tianwen Dacheng Guankui Jiyao"(1653). Then Seki Takakazu(Kowa)(1642? -1708)studied and arranged this book. Therefore Japanese mathematician in the Edo period knew this method and its name.
|
