漢初百年（前206──前104）朔閏表得失論

Discussion of the Calendar Tables for the Early Han Dynasty (206 B.C.-104 B.C.)

歷來學者編排漢初百年朔閏表，各不相同。個中緣由，一則誤解藉半日法，一則誤解閏法。漢初朔閏雖據颛頊術及藉半日法，但藉半日法在文帝後元年前後有所變化：文帝後元年以前，藉半日法為加借朔小餘499分；自文帝後元年起，藉半日法為加借朔小餘的470分。其閏法之變化：文帝後元年之前，凡閏在人正十月以後者，皆移閏於下年；自文帝後元年起，凡閏在人正十月以後者，皆閏本年，不移於下年。據此，即可推排出準確的漢初朔閏表。

Discrepancies exist among the calendar tables for the first century of the Han dynasty produced by scholars down the ages. These have arisen due to misunderstandings of methods for borrowing a half day 藉半日法 and for establishing intercalary months 閏法. At the beginning of the Han dynasty, these calendar tables were calculated according to the Zhuanxu calendar 颛頊曆 and the method of borrowing a half day. However, this method was altered at the beginning of 163 B.C. during the reign of Emperor Wen 漢文帝, resulting in discrepancies in the calculations. A change was also made to the method of establishing intercalary months. Initially, in all years where an intercalary month was needed, that intercalary month was added to the following year; but from 163 B.C. onwards, necessary intercalary months were added to the current year, not the following year. A correct understanding of these changes allows the production of accurate calendar tables for the beginning of the Han dynasty.