The origin and time of three volts

The dog days are determined according to the ancient "method of keeping records of cadres and branches" in China. "V" means hiding in a hot place, which has a warning effect. Geng, heaven is the seventh, and the five elements belong to gold. Gold is afraid of fire, which decreases day by day in a few volts, so the ancients counted it as "volt" on Geng Day.

Every summer to the future, the third Geng Day (referring to the day with the word "Geng" on the trunk and branches) is the beginning period, the fourth Geng Day is the middle period, and the first Geng Day after beginning of autumn is the end period, collectively referred to as the dog days. According to the solar calendar, it appears from mid-July to mid-August. At this time, most parts of our country are the hottest season of the year.

The first and last days are fixed at 65,438+00 days, and the middle days are not fixed. When there are four Geng days between the summer solstice and the beginning of autumn, the intermediate days are 65,438+00 days, and when there are five Geng days, the intermediate days are 20 days. So some years are 30 days and some years are 40 days.