The ingenious world time mechanism, which corresponds the 24-hour display ring with the names of major cities in the world's 24 time zones, was invented by Louis Cottier, an independent Genevan watchmaker, in 1935. Patek Philippe's first wristwatch, the 515 HU, was released in 1937. It featured a dial with the names of 28 cities and regions of the world engraved on it, a unique square case, and was a pioneer of world time watches. It was manually wound (Caliber 10'''HU). From the Patek Philippe Museum.
Text by Shigeru Sugawara
As mentioned above, GMT watches, which basically display two time zones, first came into full use in the mid-1950s when global travel by jetliner became popular, and became popular among airline pilots and travelers.In contrast, it was not until the late 1930s, 20 years before the GMT watch, that "world time" watches, which simultaneously and comprehensively display the time in 24 time zones around the world, were realized on wristwatches.
At the International Meridian Conference held in 1884, the world was divided into 24 zones (time zones) each consisting of 15 degrees of longitude, and a system of standard time was established with GMT as the base point. Since then, many manufacturers have been working on developing mechanisms that can display more than one time on a single watch, but this has been nearly impossible with the limited size of wristwatches.
In the 1930s, a definitive solution to this problem was found by watchmaker Louis Cottier and the Geneva watch manufacturer Patek Philippe. The "world time" mechanism, credited to Louis Cottier's invention, placed a ring that rotated once every 24 hours on the outside of a regular watch that rotated once every 12 hours. The 24-hour numerals on this rotating ring corresponded to the names of major cities in the world's 24 time zones, allowing the time in all 24 different places to be displayed simultaneously. Patek Philippe's wristwatches, named "HU" in French ("World Time" in English), began with the 515 HU in 1937, and went on to produce numerous masterpieces that truly set the standard for world time.
Commonly referred to as the "Louis Cottier system," this world time system uses the same principles as a GMT watch, but what makes it so outstanding as a system is that it provides a wealth of time information with a simple rotating mechanism. The rotation of the 24-hour ring is similar to the image of the sun making a circuit around the world's cities over the course of a day. It conveys the transition of time from city to city, while also beautifully visualizing the passage of time in a single city throughout the day.
