The Annuary Calendar is a Calendar invented by Karl Palmen in which each year has twelve regular months alternating between 29 and 30 days plus a 30-day intercalary month occurring once every 33 months.
Such a calendar has an 8-year cycle of 99 months with a mean year of 365.25 days. To reduce the mean year to 365.2425 days three intercalary months every 400 years have 29 days (instead of 30 days).
The mean month is a little short of a lunar month and the calendar has a rule to reckon the slow drift of the moon phases against the calendar month.
The Months
The months are named thus.
Annuary, Bebry, Carch, Daipril, (Eapril), Fay, Gyne, Huly, Igust, (Jawgust), Keptember, Luctober, Myvember, Nicember, (Ocember).
Eapril, Jawgust and Ocember are intercalary months. Each one occurs once every 8 years.