The Breguet Tourbillon Équation Marchante watch weaves together three threads from the storied Breguet history. First, its legacy of the invention of the tourbillon, patented by founder Abraham-Louis Breguet in 1801. Second, the combination of the latest generation tourbillon with a perpetual calendar and an equation of time, and finally, it recalls the company founder’s appointment in 1815 by the King of France, Louis XVIII, as Horloger de la Marine Royale, the official watchmaker of the French Navy. The connection with the ocean is established with a guilloche-peaked wave motif at the center of the dial, as well as hand carving of an image of an ancient flagship of the French Navy, the Royal Louis, across the bridges of the movement that can be seen at the back. The stand-out complication of the watch is the display of the equation of time. It is essentially the time difference between our ‘civil’ time, based on the conventional 24-hour period, and a ‘true’ solar time measured as the precise time that the earth takes to rotate fully, with respect to the sun. In a regular watch (also known as the civil clock), a standardised day is always constant at 24 hours, while in reality, because of the earth’s tilt and its elliptical orbit around the sun, the perfect 24-hour day is achieved only on four occasions in a year (April 15, June 14, September 1, and December 24). During the rest of the year, the day is slightly longer or shorter. This variation in time is a daily occurrence, resulting in shorter days during winter, and longer days in summer. At its shortest, on November 4, the day is 16 minutes and 23 seconds shorter than 24 hours. And at the longest, on February 11, the day clocks 14 minutes and 22 seconds longer than 24 hours.
The Breguet timepiece features two minute hands, one for the civil minutes, and the other with a faceted sun that displays the solar time (civil time plus equation of time). The latter is connected to a transparent sapphire disc, with months of the year marked along its perimeter, whose movement faithfully duplicates the equation of time cycle, completing a full rotation in a year. With the two minute hands, the owner, at a glance, can read both the civil time and solar time. The equation of time display on the watch is paired with a perpetual calendar, which obviates all the irregularities of the four-year calendar cycle, the months of 30 or 31 days, and the month of February of 28 or 29 days during the leap year, and displays the correct date and day without any adjustment. The calendar display is unique among Breguet collections and features a newly constructed mechanism. Rather than with hands, the day of the week and the month are shown in small windows. The date is indicated with a retrograde hand, which advances along an arc until the end of the month, and then reverses course by snapping back to ‘1’ to start the next month.
Both the complications are powered by the extra-thin self-winding tourbillon movement. The timekeeping elements of the watch, its balance wheel, spiral, and the escapement, are located within a carriage that makes one rotation per minute. The tourbillon carriage is made from titanium, while the balance wheel’s spiral, as well as the escape wheel, are fashioned in silicon. It provides a power reserve of 80 hours, which is shown by a gauge-type indicator at 8 o’clock. The 43.9mm case is made in rose gold for the first time, in this collection. The slate-grey dial in gold is engine-turned by hand and individually numbered, with a Breguet signature. The day window is between 10 and 11 o’clock, month and year between 1 and 2 o’clock, and the retrograde date on a circular arc is running from 9 to 3 o’clock.