Two Marine Tourbillons
by Jeffrey S. KingstonIs it possible to marry, in a single timepiece, an ultra-complicated movement, exquisite métiers d’art, and a sport chic nautical style? Enter two exceptional Breguet Marine collection timepieces: the Tourbillon Équation Marchante 5887 and Tourbillon 5577.
The Tourbillon Équation Marchante 5887 is a world first. Never before had a running equation of time perpetual calendar complication been combined with an extra-thin automatic winding tourbillon. The running equation of time naturally fits with the notion of a nautical timepiece. The measurement of longitude in marine navigation historically depended upon the relationship between solar fixes and civil time.
As a vessel changed its longitudinal position, solar noon would occur at different times in reference to its starting point. For example, when sailing westward, solar noon would occur later in reference to noon at the starting location. This difference in time could then be translated into a longitudinal position. The Breguet Marine’s running equation of time display, although not directly measuring longitudinal changes, fully captures the spirit of this interplay.
Equation of time displays are a rare complication. The indication shows the difference between the standard 24 hour civil time day, which remains unchanged throughout the year, and solar time (generally measured from noon to noon the next day1), which, owing to the tilt of the earth’s axis and slight imperfections in the orbit around the sun, is slightly longer in some months, shorter in others. The accumulation2 of these differences places the solar minutes as much as 14 minutes ahead of civil time or 16 minutes behind.
On four days of the year, April 15, June 14, September 1, and December 24, there is no difference. With only a minuscule number of exceptions, wristwatches have shown this difference with a plus/minus display. It is ultra rare, and a significantly more complicated construction, to illustrate the difference by means of an additional minute hand, bearing an image of a sun, which directly shows solar time. The Breguet Marine timepiece is of the latter variety as it features this form of the complication termed “équation du temps marchante” (running equation of time). Paired with the running equation of time complication is a perpetual calendar.
¹ To be more precise, the length of the solar day is defined as the amount of time it takes for a point at the equator to rotate 360 degrees with reference to the sun.
² Day to day, the difference between the length of the solar day and the civil day is only a matter of a few seconds. However, these differences accumulate so that solar time and civil time diverge by several minutes at certain times of the year.
Both the Marine Tourbillon Équation Marchante 5887 and the Marine Tourbillon 5577 share Breguet’s extra-flat tourbillon as the base movement, a construction which itself abounds with technical innovations. There are some ultra-flat movement constructions that strive for record thinness, but in doing so impose significant compromises in robustness, power reserve and performance. Breguet has chosen the opposite route: using clever designs to produce an elegantly thin movement with no compromises in robustness, power reserve, or performance. There was no one silver bullet in achieving the slim construction. One of the key elements is the automatic winding system. The design is extraordinarily sophisticated as it utilizes a peripheral rotor which, not only contributes no extra thickness to the movement, but also allows an unobstructed view of the movement’s bridges.
These two Marine tourbillons embody a marriage of mechanical complexity, artistic crafts, and nautical spirit.
Not only does the tourbillon porthole offer a view of the tourbillon components, it also presents the elipsoidal equation of time cam.
Contrast conventional winding rotors positioned above the movement bridges, which, by adding an extra layer, thicken the construction and also cover the view of the components directly below. Similarly, the tourbillon avoids adding an extra layer with two clever constructions. First, the gear train that powers the tourbillon does so via the exterior of the tourbillon carriage (instead of the more conventional pinion below). Second, the fixed wheel, an essential component of every tourbillon, has also been placed on the exterior (again in contrast to conventional designs placing it below the carriage). There are other important design innovations that distinguish Breguet’s extra-flat tourbillon; for a comprehensive discussion see Le Quai de l’Horloge No. 7.
There is a significant additional benefit to the peripheral winding rotor design, since it does not block the view below, it permits the Marine Tourbillon Équation du Temps to become a showcase for Breguet’s master engravers. Using the movement bridges and the winding barrel as their canvas, the engravers create two elaborate nautical motifs. Upon the bridges, using the classic technique of taille douce appears the image of the French Navy’s Royal Louis sailing vessel finely carved in sumptuous detail. With the Tourbillon 5577, the movement bridges are decorated with fine hand applied anglage and striping along the surface in the style of nautical wooden planking. For the winding barrels of both tourbillons, the engravers created hand-engraved presentations of a compass rose.
