A date with time

Apart from telling time, perpetual calendar mechanical timepieces, as the name suggests, also tell the day, date, month and moon phase without - at least in our lifetime - the need for hands-on correction for the different number of days in February and the extra day gained every four years for leap year; the watch's mechanism makes all the necessary adjustments to ensure the date is correct.

Perpetual calendar timepieces are more sophisticated than their less complex offshoot - the annual calendar watch, in which you would have to manually push the last day of February - be it 28 or 29 - forward to 1 every year on March 1.

A much sought-after "useful" and enchanting complication watch today, the perpetual calendar timepiece was invented by Englishman Thomas Mudge (1715-1794). A perpetual calendar watch he made in 1762 now resides in the British Museum. It's the oldest known perpetual calendar timepiece.

Perpetual calendar watches, especially those worn on the wrist, are more linked to Swiss luxury watch company Patek Philippe in modern times. Patek, which also introduced the annual calendar watch in 1996, started making perpetual calendar pocket watches in 1862 and was granted a patent protection for its mechanism in 1889. In 1925, the Geneva-based company made the first perpetual calendar wristwatch using a women's pendant watch movement it produced in 1898.

Initial production of Patek perpetual calendar watches was small but they played a big role in the days when the company supplied the great industrial barons and financial tycoons of the New World. But with the launch of Ref 1526 in 1941, the first regular series-produced perpetual calendar wristwatches took off - and soon reached out to a wider market.

Patek has continued to launch new perpetual calendar timepieces, the latest being Ref 5320 introduced this year. This latest model, inspired by Ref 1526 which in 1941 kicked off perpetual calendar watches as part of Patek's regular collection, automatically indicates months with 28, 30 and 31 days and every four years also recognises Feb 29 as a leap day.

A recent exhibition of Patek Philippe perpetual calendar timepieces in Singapore showed the company has created at least 30 models between 1925 and 2017, not counting the multiple complication timepieces which feature a perpetual calendar.

Milestone pieces

01. Movement 12''

Patek's first perpetual calendar wristwatch, which was named after its hand-wound movement housed in a 34.4mm yellow gold case. The watch indicates the day of the month. A golden hand centred on the dial jumps correctly from one month to the next - also in a leap year. A sub-dial at 6 o'clock tells the month.

02. Ref 1526

Patek's first series-produced perpetual calendar timepiece launched in 1941, it also set the signature dial configuration for later models: two rectangular apertures displaying the day and month in the upper half of the dial, with the moon phase and date on a sub-dial below.

03. Ref 3448

This is the first Patek perpetual calendar watch to be powered by an automatic movement, nestled in a larger 37.5mm case. Until this watch came along in 1961, the case-size of Patek perpetual calendar timepieces was around 34mm.

04. Ref 5050

Patek's first perpetual calendar timepiece with retrograde hand. The model was introduced in 1993 in a 35.4mm yellow gold case with a self-winding movement. Two years later, Patek released pink gold, white gold and platinum versions of the model.

05. Ref 7140

A first for the ladies, this Patek perpetual calendar timepiece launched in 2012 came in a 35.1mm rose gold case. It is driven by an ultra-thin automatic movement, 240Q, built in-house specially for Patek perpetual calendars. The movement was first used in 1977.