CALIPPIC PERIOD, an improvement of the cycle of Meton, of nineteen years, which Calippus, a famous Grecian astronomer, finding in reality to contain nine-
teen of Nabonassar's years, four days, and , he, to avoid fractions, quadrupled the golden number, and by that means made a new cycle of seventy-six 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 seventy-six years before.