Twenty-four solar terms 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.

Song's "Count Nine" solar terms 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. It means entering the dog days from summer to the third "night" in the future, with initial lodging 10 days, intermediate lodging 10 days or 20 days, and final 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 the dates for recycling. The day with the word "Geng" is called "Geng Day". The word "Geng" on 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.