World Time Complication
The mechanism was developed by Geneva watchmaker Louis Cottier in the 1930s and first commercialised by Patek Philippe in the reference 515 HU (Heures Universelles) in 1937. Cottier supplied his module to Patek, Vacheron Constantin and Rolex during the same period, establishing the convention - still used today - of pairing a fixed city ring with a 24-hour disc that rotates once per day.
Reading a world-timer
Identify your reference city on the outer ring; the hour aligned with that city on the inner 24-hour disc is the local time everywhere on the dial. Day-time hours are typically rendered light, night-time dark.
Modern references
Patek Philippe Calatrava World Time (current ref. 5230, evolved through 5110, 5130, 5131); Vacheron Constantin Overseas World Time (37-zone display, 2016); Jaeger-LeCoultre Geophysic Universal Time; Frédérique Constant Manufacture Worldtimer (the most accessible mainstream world-timer).
Key facts
- ▸Mechanism by Louis Cottier, 1930s.
- ▸Patek 515 HU (1937) was the first commercial wristwatch implementation.
- ▸Vacheron Overseas World Time displays 37 zones (vs the standard 24).