What was the original definition?

1, the first lodging date is from summer to the third Geng day in the future.

The dog days are the hottest time of the year. The dog days appear between the light summer heat and the heavy summer heat, and it is the hottest, humid and sultry day of the year. "V" means it's too hot, so you should lie still. It is the hottest thirty or forty days in a year in the Central Plains. According to the lunar calendar, it is between mid-July and early August in the solar calendar.

3. The time of accommodation is not fixed every year, and the length of accommodation is also different. You need to consult the almanac to calculate. Simply put, the lodging date can be expressed by the formula of "three Geng", that is, from summer to the third Geng day in the future, the initial lodging is 10 day, the intermediate lodging is 10 day or 20 days, and the final lodging is 65438. In ancient China, the "trunk-branch calendar" was popular, and 60 groups of different names were used to record dates with 10 heavenly stems and 12 earthly branches, which were recycled.

4. The day with the word "Geng" is called "Geng Day". The word "Geng" in Geng Day is the seventh word in "A, B, C, D, E, Ji, G, Xin, Ren, Gui" 10 day, and it is repeated every 10 day. Starting from the summer solstice, according to the date of trunk, the third Geng day is the first, the fourth Geng day is the middle, and the 1 th Geng day after beginning of autumn is the last. When there are four Geng days between the summer solstice and the beginning of autumn, the middle part is 10 days, and when there are five Geng days, the middle part is 20 days.

I see. You have gained knowledge!

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