Wittnauer annual calendar
The complex 'ANNUAL CALENDAR' dial is very easy to read & set the calendar around two apertures at 12 and 6. It uses tables and a revolving scale to reckon the day of the week for a given date. The years and days of the week are printed on the revolving disc & aligning the year with the month on the lower table (at 6), places each day of the week above one of seven columns (at 12) that contain the relevant days of the month. An engineering marvel invented by Orient & later the rights were sold to Wittnauer.