WDS XXIII VII MMXXII

WDS XXIII VII MMXXII PERPETUAL CALENDAR

WDS 23 07 2022 PERPETUAL CALENDAR

What is a Perpetual Calendar and What Does it Do

As its name implies, a calendar watch is one that indicates calendar information, which can include either one or a combination of the following: date, day, month, week, year, and moonphase. For instance, a time and date watch is a simple calendar watch. On the other hand, a perpetual calendar is one of the most mechanically sophisticated calendar watches there is.

A standard calendar watch has a date disc with 31 days, therefore, the wearer must manually adjust it at the beginning of each month if the previous month has less than 31 days. For example, April only has 30 days, so on the first of May, the date window on the watch has to be manually advanced from 31 to 1. Alternatively, an annual calendar is more complex because it can differentiate between months with 30 and 31 days. However, it does not take into consideration the fewer days in February. Therefore, an annual calendar watch must be manually adjusted once a yearon the first day of March. The rest of the year, an annual calendar watch will automatically adjust to indicate the right date, date, month, and so on.

Even more complex is the perpetual calendar complication remember, a complication is any function on a watch that goes beyond telling the time. A mechanical masterpiece, not only does a perpetual calendar take into consideration all the different days of the 12 months, but also, the occurrence of a leap year every four years. So a perpetual calendaras suggested by its namedisplays the correct date and year cycle and subsequently day, month, and moonphase too in perpetuity.

Well, thats not entirely true. In the year 2100, what would ordinarily be a leap year according to the four-year cycle, will, in fact, be ignored according to the standard Gregorian calendar. So, a perpetual calendar will have to be manually adjusted in 2100. However, thats well beyond our lifetime, so for our purposes, a correctly set perpetual calendar will continue to tell the correct time and date as long as the movement keeps running.

Brief History of the Perpetual Calendar

Rudimentary examples of the perpetual calendar complication date back as early as the 1600s, when English clockmaker Thomas Tompion and his famous successor, George Graham used it in clocks. However, it was an English horologist named Thomas Mudge the same man that invented the lever escapement, which is still ubiquitous to modern mechanical watches that adapted the perpetual calendar complication for a pocket watches in the 1700s. There are two perpetual calendar pocket watches made by Mudge that are currently known to exist; one sits in the British Museum dated 1764 and the other dated 1762 was purchased by the Patek Philippe Museum in 2016.

It is fitting that Patek Philippe purchased the earliest known example of a perpetual calendar pocket watch since it is Patek Philippe that is credited for creating the worlds very first perpetual calendar wristwatch. In 1898, Patek Philippe developed a perpetual calendar complication capable of keeping time, date, day, month, year and moon phase and fitted it into a womans pendant watch. However, there were no buyers for that mechanically advanced piece.

So, in 1925, Patek Philippe re-cased the movement in a yellow gold 34.4mm case and the first perpetual calendar wristwatch was born. The watch was ultimately sold to American watch collector Thomas Emery in 1927 and it has now found its way back to the Patek Philippe Museum in Geneva.

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