Only perpetual calendars meet the basic condition of allowing the
deduction of any of their essential data from the others (the numbers of
the year, month, week and day). But almost all known analog perpetual
calendars have little of perpetual, their calculations are limited to
about 50 years.
This calendar runs from January 1, 1600 to
December 31, 2799. It is based on the 400 year repeating cycle and the
solar cycle which is 28 years.It works by the "Sunday letter".
Brass calendar, engraved on both faces
Includes a wooden stand
Includes a booklet (in English) with history and uses
Diameter: 9 cm
Designed and produced in Madrid, Spain
[$, £, CHF...]