What is a twelve-year calendar?

19 12, Yao published the article "My humble opinion on changing the calendar" in the 23rd issue of Journal of China, proposing to abandon the lunar cycle and take beginning of spring Day as the beginning of the year, which is called the first day. Take Changxia, beginning of autumn and beginning of winter as the first day of each quarter, which are called Yuxian, Qiu Meng and Mengdong respectively. Each breath is divided into three months. Thus, summer air in April, May and June includes days, autumn air in July, August, September and March includes 92 days, spring air in June 1, February and March includes 9 1 day, and winter air in June 10,1. Such solar terms are always fixed at the beginning of the month, but the days n and j included are uneven.

1927 Zhang Zhaolin further improved this scheme. Cancel the name of digital month and change it to Meng Chun, Midspring, Ji Chun, Xia Meng, Midsummer, the last month of summer ... Mengdong, Winter Solstice and Jidong *** 12 "month", and fix the number of days in each month as 30 days or 3 1 day, so the solar terms in China always fall on/kloc-0.

At that time, a similar scheme was put forward abroad, but the concept of four seasons was directly used instead of China's concept of solar terms. In their scheme, the requirement that solar terms must fall on a fixed number of days has not been solved, and the monthly distribution is simply 30 days or 3 1 day. As for the extra day in leap year, it is called "empty day" and is not included in the calendar days.

Obviously, this scheme is a solar calendar scheme with evenly distributed days, and neither "moon" nor "week" corresponds to days.

In fact, the pioneer of this scheme was Shen Kuo in Song Dynasty, who put forward the theory of twelve qi calendars in Meng Qianbi's Talks. Shen Kuo wrote; "Every day comes and goes, called a day, and the full moon is called a month. However, on September 29th, it is strange. It will meet the sun, and it will be twelve years old. In a few days, it will accumulate in March1February, and it will end after a while. Qi is gradually leaving the new moon, and it is not this month. Nice name. January is a leap. The leap was born out of necessity and is still used as a wedge. "

Shen Kuo further pointed out that "the dispute between Qi and Shuo", "the confusion between years", "the loss of position at four o'clock" and "the gain and loss of observing the moon is not the comfort of years".

Therefore, Shen Kuo put forward: "If we take 20 Qi as a year, not to mention December, we will take the day of beginning of spring as the day, and the day of fright as one of the days in mid-spring. It should be as long as 3 1 day and as short as 30 days, and we will spend all the years without any leap. December is often one big and one small. "

Although Yao He didn't explain the origin of their plan, Shen Kuo's proposal was very clear hundreds of years ago, and it should be considered that Yao and Zhang inherited their reform plan.