Follow the Sun

Creativity, innovation and impeccable aesthetics have always been key to Breguet. And the watch manufacture’s complex new version, introduced at Baselworld 2017, the Breguet Marine Équation Marchante 5887, is no different. In fact, this ‘Grande Complication’ marks the start of an all-new era for the contemporary Marine collection.

The Breguet Marine Équation Marchante 5887 is unique in that it displays the running equation of time at a glance using a ‘running’ (marchante) central hand on the dial rather than on a subdial that shows the minutes to be added or subtracted to the current civil time. It even displays the cam that controls the equation-of-time function – alongside a tourbillon and a perpetual calendar. It celebrates Abraham-Louis Breguet’s appointment in 1814 as a member of the Bureau des longitudes in Paris, a group of experts who measured the earth’s physical properties.

Equation of time
The equation of time is essentially the addition of a sundial to the modern wristwatch. It measures time according to the current position of the sun, by which the length of a day can vary by -16 to +14 minutes compared to average or civil time. The difference is called the equation of time. For practical reasons, man has divided each year into 365 and a quarter days, each day into 24 hours, and the hours into 60 minutes each. However, because the Earth’s orbit is elliptical rather than circular, the time in relation to the sun varies daily. It is exactly 24 hours long on only four days: April 15th, June 14th, September 1st and December 24th.

Because these variations occur identically on the same dates, they can be programmed into a watch movement by means of a cam making one complete rotation a year. The cam is often linked directly to a perpetual calendar so that the display of the equation of time always corresponds to the current date. The cam on the Breguet Marine Equation Marchante 5887 is shaped like a figure eight, and visible on the dial through a window that also displays the tourbillon carriage. It runs on a sapphire disk so as not to block the view of the tourbillon.

Calibre check
Based on the self-winding 581DR calibre, the new Marine Équation Marchante by Breguet also flaunts a third complication that is noteworthy in its own right: a 60-second tourbillon with a titanium carriage housing a Breguet balance with a silicon balance spring. This innovative characteristic notably enables the balance wheel to achieve a 4Hz frequency, while maintaining a particularly comfortable power reserve for a self-winding model. This 80-hour autonomy is displayed through an aperture between 7 and 9 o’clock.

Among the many things that makes this complication valuable and collectible is its rarity: while many brands makes tourbillons and minute repeaters, only a handful make an equation of time.