Twelve Chih was sasigned to each day in the old Chinese calendar. This paper clarifres the relations between 12 Chih and the diurnal motion of Big Dipper or the clock, and it shows the long term table and formula for the dayly assignment of 12 Chih in the calendar.

Il-Cohin of the 24 subseasons is found to be repeated in the period ut 103, solar yeors. And that of the date in the old Chinese calendar xear is, repeating in the period of 102 solar years. It is also found that the length of lunar month is repeating in nearly 64solar years.

The interpolation formula Chao-ch'a-shn devised for the Chinese calendar, Shou-shih-li, has been shown as the one of the 3rd order polynomial. Its 3 coefficients have been determined from the table of the Sun in Shou-shih-li. Its applications to the moon and planets are also briefly mentioned.