>

keep my inbox inspiring

Sign up to our monthly newsletter for exclusive news and trends

Follow us on all channels

Start following us for more content, inspiration, news, trends and more

© 2017 - Copyright Fondation de la Haute Horlogerie Tous droits réservés

Breguet – Solving the equation
New Models

Breguet – Solving the equation

Thursday, 20 April 2017
By The HH Journal editors
close
The HH Journal editors

Read More

CLOSE
4 min read

The equation of time complication shows the difference between mean and true solar time. The Marine Equation Marchante 5887 makes this difference instantly readable by simultaneously showing solar and civil time. This innovation is joined by a perpetual calendar and a tourbillon.

The House of Breguet now launches a worldwide exclusive model named the Marine Équation Marchante 5887. This “Grande Complication” marks the start of a new era for the contemporary Marine collection.
The equation of time is one of the rarest and most fascinating horological complications. 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.

Breguet Marine Equation Marchante 5887
Breguet Marine Equation Marchante 5887

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 read-off 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 new Marine Équation Marchante from Breguet supersedes this principle. It simultaneously indicates civil time and true time by means of two separate minutes hands. The running solar hand, adorned with a facetted golden sun, provides a direct reading of solar time minutes that is both quicker and more user-friendly. This apparently simplicity conceals an arduous construction process that few watchmakers are capable of achieving. The solar minutes hand has to meet two imperative demands: it must sweep in a conventional way around the dial, like the civil minutes hand, while also daily moving away from the latter by a distance that varies in accordance with the analemma curve, 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.

Breguet Marine Equation Marchante 5887
Breguet Marine Equation Marchante 5887

The complexity that the running equation of time brings to this model is naturally complemented on this “Grande Complication” 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.
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.
This “Grande Complication” comes with a 43.9mm-diameter case in rose gold or platinum. The rose gold version frames a silvered dial and an anthracite movement, while the platinum interpretation has a blue dial and a rhodium-plated movement. Elegance, legibility and aesthetic balance are the keynote features of these two equally sumptuous models.

Back to Top
Lily Ohalloran interview
Point of View
A moment with... Lily O'Halloran
Thursday, 20 July 2017
5 min read
Point of View
Thierry Stern : «You have to innovate, otherwise you die»
Thursday, 20 July 2017
12 min read
Vianney Halter
News
Vianney Halter, the watchmaker of future past
Tuesday, 27 September 2016
8 min read
11
Antoine and Florian Preziuso
News
In the name of the father, son and tourbillon
Wednesday, 16 November 2016
5 min read
13