Html code will be here
A GMT watch has a fourth hand and a scale that runs to 24 instead of 12. The hand goes round once a day rather than twice, so wherever it points is an hour in some other part of the world.
There are two ways watchmakers build that. In one, the hour hand jumps independently, so you set the local time and leave the fourth hand on home. In the other, the fourth hand is fixed to the movement and the 24 hour scale itself rotates: you turn the bezel until the scale lines up with the zone you want. That second one is called a caller GMT, named after the person who is not travelling anywhere but is calling someone who is.
I have looked at a lot of world time faces on Wear OS. There are good ones, and they tend to show a second small dial, a line of digital text, or a city name that changes. What I could not find was the mechanism itself. So I tried to build it, and spent most of that time discovering that the format it has to live in will not do the one calculation the whole idea depends on.
There are two ways watchmakers build that. In one, the hour hand jumps independently, so you set the local time and leave the fourth hand on home. In the other, the fourth hand is fixed to the movement and the 24 hour scale itself rotates: you turn the bezel until the scale lines up with the zone you want. That second one is called a caller GMT, named after the person who is not travelling anywhere but is calling someone who is.
I have looked at a lot of world time faces on Wear OS. There are good ones, and they tend to show a second small dial, a line of digital text, or a city name that changes. What I could not find was the mechanism itself. So I tried to build it, and spent most of that time discovering that the format it has to live in will not do the one calculation the whole idea depends on.