Portal: Watch Knowledge

A complicated mechanism (complication) for large clocks and wristwatches, which displays the correct date of the Gregorian calendar up to the year 2100 without any external control intervention. It takes account of all the short and long months, of the twenty-ninth February, and of the leap years. The necessary control is performed in the movement by so-called program wheels.

In the Gregorian calendar the year 2100 is not a leap year. Some perpetual calendars (eg by IWC) support the consideration of this exception by a single operator intervention.

After a further definition of the perpetual calendar also moon age and moon phase are included. Also a leap year indicator is possible, indicating in which year of the 4-years cycle you are.

Wristwatches with perpetual calendars were manufactured by Patek Philippe as early as 1930 …

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