Rolex created the first watch in history to feature a fourth hand — or second hour hand — with their aptly named GMT Master ref 6542 in 1954. Developed in collaboration with Pam Am Airways for their pilots flying internationally, the new complication enabled aircrews to set their watches to a second time zone using the external, rotating bezel. It’s an extremely practical complication that almost every watchmaker has adopted, whether it’s labeled a GMT, world time, dual time, or what have you.
Rolex GMT Master 6542, picture courtesy HQ Milton
Where did this originate, though? Greenwich Mean Time, or GMT, has become synonymous with a second time zone complication amongst watch circles, and although Rolex created the original complication, they certainly didn’t invent GMT.
GMT is also known as Zulu Time and Universal Time Coordinated (UTC). It all started with the trains and railways of the early 1800’s. Railways cared most about the inconsistency in times along their routes, and made the adoption of a consistent time a priority. The Great Western Railway was the first to adopt this standard time in November of 1840. Soon after, the other railways followed their lead, and in 1847 the General Post Office approved that this time be the universal standard. The times on which the trains ran and the times in the stations were all set to this standard. Since the time was set at Greenwich, a district of Southeast London, it thereby became known as Greenwich Mean Time.
Railway Station, London, ca 1880
By 1855, the majority of the clocks in Britain were all set to GMT. The British legal system was the last stubborn holdout. Until they finally switched in August 1880, they would have events happen at strange times like polls opening at 08:13 and closing at 16:13.
At the International Meridian Conference held in Washington, DC in 1884, GMT went from “London Time” to the time the rest of the world set its watch to, as it was agreed upon to be marked at the Prime Meridian. Noon GMT is the average annual time when the sun is directly above the Prime Meridian — as opposed to the exact moment, due to the Earth’s inconsistent orbital speed. In fact, the precise moment the sun is directly above the Prime Meridian can vary up to about 16 minutes from the calculated mean. All other time zones were then referenced off of GMT, thereby creating a global standard.
Greenwich Mean Time is the same everywhere and unaffected by seasons or daylight saving time (take that, George Vernon Hudson). It is used all over the world by businesses, industry, transportation and shipping companies, and the military. GMT changed the way the world travels, does business, and how we tell time across the globe. Oh right, and it also spawned a whole bunch of awesome watches. Thanks, GMT.
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