The length of 19 regression years is almost the same as that of 235 new moons.Therefore, if seven leap months are added every 19 years, the solar calendar and the lunar calendar can be reconciled.
19Regression yearAnd 235New MoonAlmost the same.thereforeYin Yang CalendarIf the method of seven leap months in 19 years is adopted and seven leap months are added every 19 years, the time gap between the regression year (the cycle of the sun) and the new moon (the cycle of the moon) can be coordinated, and the calendar can be made in a simpler way.In ancient China, this cycle was called onechapter。
In 432 BC or earlier,Mesopotamia% of the residents already know this cycle and take it as their own standard calendar cycle, but this is notGreekUsed.
China
The earliest calendar known to ChinaAncient Six CalendarThe seven leap method of 19 years is adopted.In nineteen years, the seven leap method lasted untilXuanshi CalendarAndMing calendarWas abolished.
《Zhou Bi Suanjing》Volume II: "At the age of 19Chapter 1。” Zhen Luan said, "If one thousand nine hundred and forty-eight is used to divide the new moon, one hundred and thirty-five points will be obtained, that is, the chapter month. The difference between the chapter month and the middle of the chapter is seven, that is, the leap of a chapter. If two hundred and twenty-eight are used to divide the new moon by twelve years of age, nineteen points will be obtained, that is, the chapter year."《The History of the Han Dynasty·Legal chronicle》: "Leap method 19, becauseZhang Sui……”，“Zhang YueTwo hundred thirty-five...... ".However, since the late Spring and Autumn Period (the 5th century BC), the Chinese calendar has adopted the method of intercalation in July of 19.
