Akan calendar each Akan year tends to be the various yam festivals celebrated around August or September. The lunar cycle and 28-day month are not carefully observed, except by the coastal Akan who are interested in tides as they affect fishing. Still, the month is known as "bosome". It consists of 28 days rather than the 30 or 31 days of the Gregorian calendar. Three "bosome" make two Adaduanan. Since the arrival of Swiss missionaries from Basel in the early nineteenth century, Christian Akan scholars have tended to 'Akanize' the Roman calendar rather than observe, analyse and explain the Akan calendar based
Julian calendar before the Julian reform, that the tropical year was slightly shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the calendar year gains about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was largely corrected by the Gregorian reform of 1582. The Gregorian calendar has the same months and month lengths as the Julian calendar, but, in the Gregorian calendar, year numbers evenly divisible by 100 are not leap years, except that those evenly divisible by 400 remain leap years. (Even then, the Gregorian calendar diverges from