Twenty-four solar term song? When did "counting volts" and "counting nine" start respectively?

The "several volts" of the solar term Song began at different times of the year. It starts from summer to the third Geng day in the future, starts from the fourth Geng day and ends on the first Geng day in autumn, lasting for ten days.

The "number nine" of the solar term Song began in the winter. That is, 65438+February 2 1 per year.

It is necessary to calculate the entry time according to the almanac, and the relatively simple method is to use the four-word formula of "Summer Solstice Day Three Geng" to express the entry date. This means that from summer to the third "more" day in the future, you will enter the dog days, start lodging 10 days, intermediate lodging 10 days or 20 days, and finally lodging 10 days.

In ancient China, the "chronology of trunk and branch" was popular, that is, 60 groups of different names matched with 10 trunk and 12 branch were used to record dates and recycle them. The day with the word "Geng" is called "Geng Day". The word "Geng" on Geng Day is the seventh word in 10 day of "A, B, C, D, E, Ji, G, Xin, Ren and Gui", which is repeated every 10 day.