The concept of global time zones emerged in the late 19th century, with Scottish Canadian Sir Sandford Fleming proposing the division of the world into 24 time zones, each time zone covering 15 degrees of longitude (one hour), in 1878. This idea was formalised at the 1884 International Meridian Conference in Washington, D.C., which established the Greenwich Meridian as the zero reference line for longitude and time. By 1929, major countries had adopted hour-based time zones, coinciding with the era of the first transatlantic flights and international calls. With the advent of transatlantic flights and international calls, it became a necessity to have a complication that can tell both local and international time, instead of looking at the town clock tower and mentally calculating the relevant time for a particular city.
In response to the growing need for tracking multiple time zones, Louis Cottier, a Geneva-based watchmaker, created the first world time mechanism in 1931 based on the 24 time zone system with a novel aesthetic layout that has became an iconic design for most world time complications. His ingenious concept featured two circular components: an outer stationary (adjustable) ring, displaying the 24 global time zones and an inner rotating ring for a 24-hour dial, typically split into day and night sections for enhanced legibility, which turned anticlockwise. This design enables users to read the accurate time for any city by looking at the corresponding section of the 24-hour ring aligned with the time zone.
Incorporating Louis Cottier’s horological solution, Patek Philippe was one of the earliest manufacturers producing the world time complication, from the earliest reference 1415, in 1939, to reference 2523, an updated two-crown system, in 1950. After a hiatus following Cottier’s death in 1966, Patek Philippe resumed production of world time complications in 2000 with the reference 5110 (2000-2006). Subsequent models included reference 5130 (2006- 2016) with a bigger case of 39.5mm from 37mm and later replaced by reference 5230 with an updated cities ring. In 2008, reference 5131 was launched with a cloisonné enamelled centre map and later substituted by reference 5231 in 2019. To celebrate the maison’s 175th anniversary, two references 5575 and 7175 of world time and moonphase pieces were introduced.
In 2023, Patek Philippe unveiled the reference 5530 at the Tokyo “Watch Art” Grand Exhibition, marking a significant advancement in world time complications. The maison has followed up with a regular edition with an opaline blue-gray dial a thematic colour for this year, and features a centre with a “carbon” pattern that one may relate to the reference 6007. The date is displayed on the flange by a red-tipped central glass hand which is only visible up close, presenting a mystery feeling of a floating red tip.
Embodied in a 40mm white gold case, the new calibre 240 HU C has been upgraded from the standard world time caliber 240 HU, keeping the functions such as the quick set button at 10 o’clock for local time and city disc advancement. The new date function is made up of 70 extra parts with only an increase of 0.7mm thickness on the movement.
The reference is the first world time with a date display that indexes to the local time. The date display might seem like a simple addition, though when it involves the 24 time zones, it becomes a much more complicated construction that includes the calculation on setting the date backwards when crossing the line from eastward and advancing one day when travelling westward.
Another point to note is that every day (unless summer time is in effect), there is a one hour window that the date is synchronised all over the world, a patented differential system keeping the date even when using the quick set at 10 o’clock by sending two contradictory signals to the same star-wheel, one to advance the date by a day, the other to subtract a day – which would block the movement.
From Sir Sandford Fleming’s initial concept to Louis Cottier’s innovative mechanism and Patek Philippe’s continual refinements, these world time complication timepieces have become not only a functional tool but also showing the pinnacle of horological craftsmanship.
