Calendar operating over twenty five years period - has required month and year scales aligned on two discs to bring weekdays into alignment with calendar for selected month

摘要

The calendar operating over the period 1976 to 2000 comprises two relatively rotatably discs attached together. The lower disc is divided into 28 segments having the year numbers arranged in a specified order around the edges of the segments, with three spaces being unused. The days of the week are regularly marked in a repeating pattern in the inner parts of the segments. The upper disc has two pieces removed over 90 degree arcs to display parts of the year and weekday scales, against month and day-of-the-month tables respectively. By relative rotation of the discs it is possible to select a combination of year and month in the specified period. The day-of-the-month calendar then appears in the correct position w.r.t. the days of the week.