CALLIPIC PERIOD, an improvement of the cycle of Meton, of 19 years, which Callippus the Grecian astronomer, finding in reality to contain 19 of Nabonassar's years, four days, and \frac{1}{2} of a day, he, to avoid fractions, quadrupled the golden number, and by that means made a new cycle of 76 years; which time being expired, he supposed the lunation, or changes of the moon, would happen on the same day of the month and hour of the day that they were on 76 years before.