40 Year Calendar 1994-2033 in wooden box with original packaging box.
An instrument used by sailors and navigators. It was so named because at the time, the average life span was 40-50 years. Instrument consists of 2 brass disks. Align the month on the upper disk with the year on the rim of the lower disk. Now view the calendar of that month in the lower window. Red months apply to leap years.
Excellent pre-owned condition.