The epact is the number of days which must be added to a lunar year to complete a solar year.
Thus we have the epact, or age of the Calendar moon at the beginning of the year.
Thus, when the epact is 17, the new and full moons of March fall on the 13th and 28th.
During those few and sombre days which represented the epact of the dying year, Martin Grimbal returned to Chagford.
The epact 19′ (also distinguished by an accent or different character) is placed in the same line with 20 at the 31st of December.
On account of the solar equation S, the epact J must be diminished by unity every centesimal year, excepting always the fourth.
It is, however, only used in those years in which the epact 19 concurs with the golden number 19.
Having determined the epact of the year, it only remains to find Easter Sunday from the conditions already laid down.
The epact thus continues to vary until at the end of nineteen years the new moons return as at first.
In the calendar this epact first occurs before the 2nd of December at the 26th of November.
1550s, "number of days by which the solar year exceeds a lunar one of 12 moons;" also "number of days into the moon on which the solar year begins;" from French épacte (12c.), from Late Latin epacta "an intercalary day," from Greek epaktos, literally "brought in, inported," verbal adjective of epagein "to intercalate, add, bring forward," from epi "on" (see epi-) + agein "to bring, to lead" (see act (v.)).