In ancient China, "Fu" meant that the weather was hot. Every year, "Fu" days in the northern hemisphere began after the slight summer heat and before the great summer heat. According to the astronomical calendar, "Fu" days were "three volts", which were called "head fu", "middle fu" and "last fu" (also called one volt, two volts and three volts), totaling 30 or 40 days. The beginning date of "Toufu" must be the third Geng day after the summer solstice (one Geng is 10 day), that is, as the saying goes, "the third Geng in the summer solstice is Fu". The third day with "Geng" is the beginning date of "Toufu", such as1July 1997/kloc-0. That is, the day when "Toufu" began. It must be emphasized here that this kind of cooperation between the heavenly stems and the earthly branches began thousands of years ago, and in this cycle, when it is scheduled to1July 17 in the Gregorian calendar in 997, it is just the "Geng Shen" day, not the temporary cooperation of that year. Usually, the summer solstice every year Over the years, the "first fall" (also known as the first fall) began in mid-July. The fourth Geng day after the "Summer Solstice" is the beginning day of the "middle fall", while the first Geng day after the "beginning of autumn" is the beginning day of the last fall, that is, the last fall takes the solar term "beginning of autumn" as the starting point, so the middle fall to the last fall is not necessarily/. The "first lodging" and "last lodging" are fixed every 10 day. If there is any change, it will only change in the days of "middle lodging". The "middle lodging" is either 10 day or 20 days, and it is absolutely not allowed to appear in the middle lodging 1 1 day or/kloc.