Photograph by Tom Schierlitz
The most practical complication for international travelers traces its existence to the International Meridian Conference of 1884, which divided the globe into 24 time zones. Swiss watchmaker Louis Cottier developed the first world-time wristwatch for Patek Philippe in 1937, the basics of which are still the standard today: a 12-hour dial, surrounded by a 24-hour scale with day/night indication, and an outermost, rotatable disk printed with the names of 24 cities, each corresponding to a different time zone. By lining up one’s present city with its current time on the 24-hour scale, one can read the correct time in the other cities simultaneously. Vacheron Constantin’s Patrimony Traditionnelle World Time even accounts for today’s expanded system of 37 time zones.