The Breguet Marine Équation Marchant 5887 is a technical marvel of a timepiece. With the inclusion of two distinctive minutes hands, it is able to simultaneously indicate both civil hours and minutes as well the actual solar hours and minutes, between which there can be a difference ranging from minus 16 minutes to plus 14 minutes, through the course of a year.
Abraham-Louis Breguet– the late 18th-century founder of the house of Breguet – was not just a visionary and a watchmaking genius for the ages. He also had an abiding interest, throughout his career, in precision marine instruments, which incorporated technology that was very similar to that used in timepieces. His work was so renowned that King Louis XVIII appointed him to the Bureau des longitudes in 1814. This prestigious body was dedicated to the advancement of the various branches of astronomy and their applications to geography, navigation and geodesy (the measurement and understanding of the earth’s physical properties). Of its 20 or so members, that included geometers, astronomers, seafarers and associate artists, Breguet was the only horologist, notable for the calculation of longitudes at sea. Later, through an ordinance issued in 1815, Louis XVIII awarded Breguet the official title of chronometer maker to the French Royal Navy, which was the most prestigious title a horologist could hope to receive, given that the concept of marine chronometry implied scientific knowledge. It also involved playing a crucial role for the country, as marine chronometers were of crucial importance for fleets by making it possible to calculate ships’ positions at sea.
With this illustrious heritage in mind, the house of Breguet has launched an exclusive model called the Marine Équation Marchante 5887. This “Grande Complication” marks the beginning of a new era for the contemporary Marine collection.
The concept behind this unique watch has its origins in something that has been used to tell the time for millennia —the sun. Although it has always been used as the basis for time, the visible movement of the sun — what is referred to as true solar time — is irregular, and with improvements in timekeeping technology, true solar time came to be replaced by mean solar time — ‘civil’ or ‘standard’ time — whereby each day had a fixed duration of 24 hours. However, the difference between the two —the equation of time — ranges between minus 16 minutes to plus 14 minutes, in the course of a year. The equation of time is an important factor for astronomers and navigators, and the new Marine Équation Marchante 5887 features a unique complication that shows the difference between the two (the ‘running equation of time’). It also features a perpetual calendar, a tourbillon and a power reserve indicator.
The watch’s technical centrepiece is a cam, shaped like a figure of eight. It mechanically reproduces the path of the sun’s successive positions, which is called an analemma curve. On four days a year, civil and true solar times are exactly the same. Since 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 this special cam.
Normally, this cam is coupled with a feeler-spindle, which drives an equation lever that serves to indicate the difference between civil time and solar time. This read-off is generally provided on a sector or subdial, and the wearer then has to mentally add or subtract the difference displayed in relation to mean time, in order to calculate true solar time. However, the Marine Équation Marchante supersedes this principal.
The watch does this by simultaneously indicating civil time and true time by using two separate minutes hands. The running solar hand, with a facetted golden sun, provides a direct reading of solar time minutes, making it quicker and user-friendly. Seemingly simple, this is achieved by a very complicated construction process. The solar minutes hand has to meet two demands: it has to sweep in a conventional way around the dial, like the civil minutes hand, and also daily move away from the latter by a distance that varies in accordance with the analemma curve, in order to display the equation.
Breguet has accomplished this by equipping the running solar hand with a differential gear, powered by two rotation sources operating completely independently: the rotation of civil minutes, and the one 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 supported by a transparent sapphire disc, which also serves to correct the equation of time by month.
The complexity of this mechanism is complemented by a perpetual calendar. 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 the information has been carefully designed to ensure simple and intuitive linear reading, along with impeccable visual appeal.
Based on the self-winding 581DR calibre, the watch also has a third complication, a 60-second tourbillon with a titanium carriage, housing a Breguet balance with a silicon balance spring. This innovative characteristic enables the balance wheel to achieve a 4Hz frequency, while maintaining an 80-hour power reserve, displayed through an aperture between 7 and 9 o’clock.
The Marine Équation Marchante 5887 features new aesthetic signature codes, giving it a completely modern and dynamic appearance. The central lugs have polished and satin-brushed surfaces, there is more open fluting with visible flanks, a crown topped with a polished “B” against a sandblasted background, and a crown with a chamfered and satin-brushed wave motif.
The engraving on the watch consists of hand-carved designs or engraving script, and the bridges, which are visible through a sapphire caseback, are delicately chased to depict the Royal Louis, a first rank vessel in the French Royal Navy. The barrel is adorned with a windrose motif, in reference to astronomical navigation. Additionally, since A-L Breguet was the first to introduce guilloche decoration to watch dials, Breguet continues this tradition by hand-turning the gold dials on rose engines. The dial of the Marine Équation Marchante 5887 has an exclusive type of engine-turning in a wave pattern, especially developed for this piece. The inscription “Marine royale” is engraved on the tourbillon bar.
This magnificent “Grande Complication” comes with a 43.9mm-diameter case in rose gold or platinum. The rose gold version featured here frames a silvered dial and an anthracite movement, while the platinum version has a blue dial and a rhodium-plated movement. The hours chapter has Roman numerals and luminescent dots. The strap is in alligator leather. The watch is water resistant to a depth of 100m.