《历象考成后编》的“均数”和“推日躔法”

Junshu in Lixiang Kaocheng Houbian

太阳运动的“盈缩差”概念 ,是中国古代历法中的基本概念 ;《历象考成后编》中的“均数”相当于“盈缩差”。文章从《历象考成后编》相关术文中推导出“均数”计算公式 ;明确《历象考成后编》中“日躔数理”所依据的天文学理论模型是“颠倒的”“简化椭圆” ;在这一模型中 ,地球位于太阳视运动椭圆轨道上的一个焦点 ,而第二向径 (即太阳与另一焦点的联线 )作匀速旋转。

The concept of yingsuocha,one of the basic concepts in ancient Chinese astronomy,is equivalent to the concept of Junshu in Lixiang Kaochen Houbian.The formula for junshu in the Theory of the Solar Equation,volume 1 of Lixiang Kaochen Houbian,was expressed in trigonometric function,not solved in the form of Kepler's equation.The theoretical model of astronomy for the solar motion was “the simplified elliptic”,which had been invented by Western astronomers in the 17th century,although it calculated the solar parameters by making use of Isaac Newton's value 365~d.24233442 for the sidereal year,as it was pronounced.