The new Breguet Marine Équation Marchante 5887 watch — cased in choice of platinum or rose gold — features a running equation of time, a perpetual calendar and a tourbillon. Undoubtedly the star of show for Breguet this year (Baselworld), this impressive new grand complication is unmistakably inspired by A.L. Breguet’s unique heritage in timekeeping in general and marine chronometry in particular. The “equation of time” is one of the rarest and also fascinating horological complications due to its abstract nature for most. It serves to display the difference between mean solar time, corresponding to civil or standard hours and minutes, and true solar time, meaning the actual solar hours and minutes. The new Marine Équation Marchante from Breguet takes it one step further simultaneously indicating civil time and true time by means of two separate and easy-to-read minutes hands. While an impressive feat in and of itself, what would a Breguet grand complication be without the brand’s defining complication, a tourbillon? And further, a perpetual calendar? Yes, the Marine Équation Marchante 5887 has them both. Full breakdown on this superb new piece from Breguet, below.
Breguet Marine Équation Marchante 5887
43.9mm case in platinum or rose gold. Engine-turned dial in gold. Hours chapter ring with Roman numerals and luminescent dots. Breguet open-tipped hands in gold with luminescent material. Running solar hand with facetted golden sun. Aperture for days of the week, aperture for months and years, retrograde dates indication and power reserve.
Self-winding movement with running equation of time, perpetual calendar, tourbillon and 80 hours power reserve, Cal. 581DPE. Escapement wheel and spiral in silicon.
Two apertures – one between 10 and 11 o’clock and the other between 1 and 2 o’clock – respectively display the days of the week as well as the months and the leap-year cycle. The date appears inside the chapter ring by means of a retrograde hand tipped with an anchor motif and sweeping across an arc running from 9 to 3 o’clock. The dial layout of all this information is well laid out for simple reading.
The front dial features two types of engine turning, including a “wave” pattern specifically developed for this new creation. The inscription “Marine royale” is engraved on the vertical plan tourbillon bar (look closely you can see it below). The tourbillon is a 60-second tourbillon with a titanium carriage housing a Breguet balance with a silicon balance spring and 4Hz frequency. The 80-hour power reserve is very subtly displayed through an aperture between 7 and 9 o’clock (also visible below — look closely!).
Equation of Time Complication
Since Antiquity, the sun has been used as the basis of time. Nonetheless, the visible motion of the sun – the true solar time indicated on sundials – is irregular. With the improvement of timekeeping precision, watches and clocks became the basis of time and true solar time was replaced by mean solar time, within which each day has the same duration of exactly 24 hours. Mean solar time may show a discrepancy with true solar time ranging from minus 16 minutes to plus 14 minutes. On just four days a year, the two times are exactly the same. Given that the sun’s various positions in the sky are reproduced in an identical manner on the same dates, watchmakers can “program” them by means of a special cam. The latter is shaped like a figure 8 and mechanically reproduces the path of the sun’s successive positions, called an analemma curve. Requiring extremely accurate execution, the cam is coupled with a feeler-spindle that drives an equation lever serving to indicate the difference between civil time and solar time (-16 to +14 minutes). This readoff is generally provided on a sector or subdial. It is then up to the user to mentally add or subtract the difference displayed in relation to mean time in order to calculate true solar time.
The Breguet Marine Équation Marchante 5887’s running solar minute hand, adorned with a facetted golden sun, provides a direct reading of solar time minutes that is both quicker and more user-friendly. The solar minutes hand sweeps in a conventional way around the dial, like the normal minutes hand, while also daily moving away from the latter by a distance that varies in accordance with the analemma curve (as described above), in order to display the equation. Breguet was able to accomplish this by equipping its running solar hand with a differential gear powered by two rotation sources operating entirely independently: the rotation of civil minutes, and that controlled by the lever in contact with the equation of time cam, which makes one full turn per year. Breguet has developed an extremely slim equation cam borne by a transparent sapphire disc also serving to correct the equation of time by month.
The view of the caliber through the sapphire caseback is equally appealing: a meticulous depiction of the Royal Louis, a first rank vessel in the French Royal Navy. The barrel is also adorned: a windrose motif, in reference to astronomical navigation. Thanks to the carefully chosen positioning of the oscillating weight on the rim of the calibre, the self-winding movement deploys the full splendour of its decoration
Did You Know?
Throughout his career, A.-L. Breguet consistently demonstrated his exceptional mastery of time measurement. His strong involvement and his revolutionary developments earned him significant recognition and numerous honors. Renowned the length and breadth of Europe, Breguet found a particularly active admirer in Louis XVIII, king of France. In 1814, the latter appointed him a member of the Bureau des longitudes in Paris. This body created in 1795 by the National Convention was dedicated to the advancement of the various branches of astronomy and their applications to geography, navigation and geodesy (the measurement and understanding of Earth’s physical properties). Its tasks included the annual publication of reference documents such as astronomical ephemerides. The Bureau des longitudes was a prestigious organization whose 20 or so members included geometers, astronomers, seafarers and associate artists. The only representative of his profession that was eminently useful to physicists and navigators, Breguet became the horological authority, notably for the calculation of longitudes at sea. As an extension of this distinction, through an ordinance issued on October 27th 1815, Louis XVIII awarded A.-L. Breguet the official title of chronometer maker to the French Royal Navy. This was the most prestigious title a horologist could hope to receive, given that the very concept of marine chronometry implied scientific knowledge. It also involved playing a crucial role for the country, as marine chronometers were of capital importance for fleets by making it possible to calculate ships’ positions at sea.