universal mechanical calculator calculating the exact time of sunrise and sunset was previously unheard of in mechanical horology. All the more so set into the few tiny square centimetres of a wristwatch case. A dream indeed, but one which Rémi Maillat, a young mathematician and watchmaker, has just turned into a reality together with the team at Krayon, his watchmaking design bureau based in La Chaux-de-Fonds.

To achieve this result, the Everywhere watch combines the five parameters that come into play when calculating sunrise and sunset – the coordinates of longitude and latitude which determine a given geographical point on Earth, the time zone, the date and the month. Thanks to a single, simple crown combined with a push-button on the side of the watch case to choose the desired setting, the wearer can adjust each of these parameters at will to discover the exact time at which the sun will appear or vanish at the place and on the day of their choosing!

Krayon, Everywhere

"You read the time around the perimeter of the dial with the aid of a blue arrow on a 24-hour scale which also indicates how long it was since the sun rose,” explains Rémi Maillat. The large, central hand points to the minutes. “A counter in the upper half of the dial tells you the longitude, between +/- 180°, indicated by the longer hand. The smaller hand indicates the UTC time zone and advances by half-increments to take into account all the time zones in use worldwide that is, including the half-hours of a handful of time zones, see list below*. If necessary, the DST (Daylight Saving Time or Summer Time) indicator allows the time to be corrected to summer time. At the centre of the main dial, on the left, a first, small hand indicates the latitude, from + to – 60°, while the other hand shows the selected parameter – date, latitude, longitude or UTC. Lastly, in the lower half of the dial, a counter shows the day and the month.”

The USS calibre (standing for Universal Sunrise Sunset) that drives the Everywhere comprises 595 parts, all specially designed and executed, which fit into a case 6.5mm thick. At the heart of the mechanism lies an equation of time which is not displayed, but which is necessary for the various calculations as complex as the results are simple – such as the time of sunrise and sunset. To achieve this, the mechanism – protected by three main patents – has 4 differentials, 84 trains and 145 gear components.

Endowed with a power reserve of 72 hours and beating at a frequency of 3Hz, this self-winding watch is fitted with a micro-rotor.

On the dial, a light-coloured circle helps visualise the duration of daylight. A darker-coloured circle represents the night and the two points where they meet indicate the rising and setting of the sun, the course of which is indicated by a blue hand. Through the seasons, and depending on the point on the globe, the duration of daylight expands or shrinks –bringing it vividly to life. A superb mathematical, horological and philosophical performance, you might say, which reminds us that our time is dictated to us by the sun.