August 7, 2006 For two centuries, perhaps the rarest of watchmaking complications has been the equation of time. Measuring the difference between the length of the solar day which constantly varies over the course of the year and the length of the standard 24 hour civil day, an equation of time display has graced only the most exclusive watches and clocks. Even more refined and exclusive has been an equation of time display which shows both solar time and civil time with two separate minute hands. In all of watchmaking history, only a handful of the most important clocks and pocket watches have featured this form of dual time, termed “equation marchante” or “running equation” display. Indeed equation marchante timepieces have been so exclusive that nearly every single one produced over the last two hundred years has been catalogued and recorded as an historically significant piece.
Thus, Blancpain startled the watchmaking world in 2004 when it revealed that it had succeeded in miniaturising the running equation complication which heretofore had only been built in large scale clocks and pocket watches. At the Basel fair, Blancpain unveiled the first wristwatch in the world featuring a running equation of time, the Le Brassus Equation Marchante. This landmark timepiece was produced in a limited series of 50 pieces which have all been long since been eagerly snapped up by passionate collectors. However to mark the seventh anniversary of Blancpain’s partnership with the Monaco Yacht Show, Blancpain has created a special limited edition Le Brassus series watch featuring an evolution of its world record breaking equation marchante movement. It is a modern convenience that the timepieces measure and display an exact 24 hour day.
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Were we more tied to the ancient sundial, we would know that length of the day changes considerably over the course of the year. The variability in the length of the solar day is the result of what some may consider two flaws in the earth’s position relative to the sun. First the orbit of the earth is not round, but in fact highly elliptical. Second instead of rotating on an axis which is perpendicular to the plane of the orbit, the earth is inclined at an angle of 23 degrees. These two abnormalities combine to produce days, which consist of a single rotation of the earth relative to the sun, of slightly longer or shorter length depending on the time of year. Ancient astronomers fascinated by movement of heavenly bodies, most particularly the most important orb in the sky, the sun, centuries ago began recording data showing the changes in the length of the solar day throughout the course of a year.
Their findings have been most commonly expressed by a complex oblong chart termed an analemma. The twin kidney shape of the analemma shows that on but 4 days a year (April 15th, June 14th, September 2nd, and December 26th - these dates change with the leap years) 24 hour civil time and solar time have caught up with each other. At other times the differences between the two may be as much as -16 minutes and + 15 minutes.
Mechanical marvels lie behind the realization of an equation of time display. Through precise calculations, watchmakers have developed a figure 8 shaped cam which mechanically mimics the analemma curve derived by astronomers. Turning once per year, this cam is used to drive a finger producing a plus minus display of the difference between solar time and civil time. Blancpain wished to go further however. Its watchmakers strove to create for the first time in a wristwatch an equation display that would simultaneously show both civil time and solar time on two separate minute hands. This was the Le Brassus Equation Marchante watch which startled the world of horologerie upon its debut in 2004.
The first of the two minute hands in this ground breaking wristwatch indicates civil time in a conventional fashion. The second minute hand, adorned with the image of a golden sun, indicates solar time. The user can thus, directly read at a glance both civil time and solar time, as well as visualize the ever changing relationship between the two.
The display of solar time on a wristwatch firmly fixes this unique Blancpain mechanical innovation in the world of nautical navigation. Historically, one of the great barriers in maritime navigation was the determination of longitude. This obstacle was surmounted by the invention of highly accurate nautical clocks, which combined with a measurement of solar time, yielded longitudinal position. Blancpain’s Equation Marchante integrating both civil time and solar time captures the spirit of this former maritime challenge.
Yet the simplicity of the appearance of the running equation display gives little hint of the prodigiously complex horological movement that lies under the surface of the dial. The remarkable mechanism of the Equation Marchante has been integrated within a self-winding movement, itself combined with the world’s thinnest perpetual calendar module. In turn the equation mechanism is synchronized with the perpetual calendar.
The great obstacle which Blancpain surmounted in the design of the running equation was finding a way to drive the solar hand from two sources, the regular running train of the watch, powering the civil minute hand, and a gear train driven by the precision figure 8 shaped equation cam. The solution was found in an innovative system of differential gears.
The solar hand is, thus, simultaneously powered by two separate sources, its position constantly effected by both. Because the solar time indication is constantly changing in real time, the term “running equation” is the perfect description.
The limited edition Equation Marchante M.Y.S. is derived from the ground breaking 2004 watch. Adding to its refinement, the equation display in this new limited edition highlights the running solar hand by dispensing with a plus minus indication which was included in the original watch.
This horological masterpiece is based upon Blancpain’s Calibre 3863 and its 364 components. Endowed with a 72-hour power reserve, this mechanical self-winding movement displays, in addition to the running equation of time by two separate hands, indications of the date, day of the week, month, leap years and small seconds at 6 o’clock. The Equation Marchante thus focuses on essentials, ensures excellent legibility, and features a brilliant blend of remarkable inner complexity and apparent outward simplicity. In keeping with the same spirit, all the components of this fabulous mechanism are chamfered, polished, rhodium-plated, decorated and assembled by hand by Blancpain’s master-watchmakers.
To celebrate this encounter between astronomy and Haute Horlogerie, a circular aperture at 6 o’clock on the dial allows one to gaze upon the equation cam, whose position portrays the universe in miniature. The small seconds hand also turns in the centre of this opening. The hand-sewn crocodile leather strap is fitted with a folding clasp in red gold. Paying eloquent homage to the master-watchmakers, designers and artisans who have contributed for the past 270 years to Blancpain’s acknowledged mastery of the watchmaking art, the Equation Marchante M.Y.S. is crafted in an exclusive limited series of 7, each hand-engraved and personalized following the owner’s wishes.View gallery - 7 images