The Order of beginning of autumn and Sanfu

The ancients also stipulated that "the third time is in autumn", which means that the third time is the last time, and it must be after beginning of autumn. In other words, it lasted 10 days, between beginning of autumn and the scorching heat, and could not be before the Mid-Autumn Festival.

Because the basis and method of ancient people's calculation of accommodation determined the specific number of days of accommodation each year, either 30 days or 40 days. Only these two forms of accommodation will not cause other days of accommodation.

The method and law of ancient people to calculate the summer solstice is "the third night returns to the summer solstice and then follows the summer solstice". The "G" here is the seventh number in the chronograph. In other words, the third "more" day after long summer is the first day of lodging.