Important Watches

Geneva, Mar 20, 2010

LOT 160

Franck Muller Platinum Retrograde Perpetual Calendar Equation of Time Franck Muller, Geneve, "Master of Complications, Perpetual Calendar, Equation of Time, Automatic?, No. 10, Ref. 76850 CC QP E. Sold on December 22nd, 2008. Very fine and rare, astronomic, cintree curvex, self-winding, water-resistant, platinum wristwatch with perpetual calendar, moon phases, retrograde monthly equation of time, 24-hour indication and a platinum Franck Muller buckle. Accompanied by a Franck Muller carrousel winding box, setting pin and Certificate of Origin.

CHF 30,000 - 45,000

USD 28,000 - 40,000 / EUR 20,000 - 30,000

Sold: CHF 28,001

C. Two-body, solid, polished and brushed, curved tonneaushaped, correctors in the band, back with four screws,domed sapphire crystal. D. Silver engine-turned with painted black Arabic numerals, inner minute and 1/5th second division, subsidiary dials for the date, days of the week, the 24 hours and the 4-year cycle, sector for the retrograde indication of the months and equation of time at 6, aperture for the moon phases below 12. Blued steel pear and double-feuille hands. M. Cal. 2800, rhodium-plated, fausses cotes decoration, 26 jewels, straight-line lever escapement, monometallic balance, shock-absorber, self-compensating flat balance spring, micrometer regulator, platinum rotor segment. Dial, case and movement signed. Dim. 35 x 47 mm. Thickness: 13.5 mm


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Grading System
Grade:
Case: 2

Very good
Movement: 2*

Very good

Overhaul recommended, at buyer's expense
Dial: 1-01

As new

HANDS Original

Notes

Equation of Time. It indicates the time difference between the true solar day and the mean solar day (or time told by a clock or watch). It has two major causes. The first is that the plane of the Earth's Equator is inclined to Earth?s orbital plane. The second is that the orbit of the Earth around the Sun is an ellipse and not a circle. Equation of Time due to Obliquity (the Earth's tilt). If the Earth's rotational axis was not tilted with respect to its orbit around the Sun, the apparent motion of the Sun along the Ecliptic would fall directly on the Equator, covering the same angles along the Equator in equal time. However, this is not the case, since the angular movement is not linear in terms of time because it changes as the Sun moves above and below the Equator. The projection of the Sun's motion onto the Equator will be at a maximum when its motion along the Ecliptic is parallel to the Equator (at the summer and winter solstices) and will be at a minimum at the equinoxes. Equation of Time due to Unequal Motion (the Earth's elliptical orbit). The orbit of the Earth around the Sun is an ellipse. The distance between the Earth and the Sun is at a minimum around December 31 and is greatest around July 1. The Sun's apparent longitude changes fastest when the Earth is closest to the Sun. The Sun will appear on the meridian at noon on these two dates and so the Equation of Time due to Unequal Motion will then be zero. The mean solar day, calculated by averaging all the days of the year, was invented by astronomers for convenience so that the solar day would always be 24 hours. True solar time and mean solar time coincide four times a year, on April 16, June 14, September 1, and December 25. On these days, the equation will equal zero. During the other 361 days, the equation of time must be used to indicate the difference between the two times, amounting over 16 minutes at certain times of year. The minimum difference occurs on November 1 with a loss of 16 minutes and 23 seconds and the maximum occurs on February 11 with an increase of 14 minutes 20 seconds. This positive and negative value is offset in the time of the local noon and those of sunrise and sunset. Equation of time, often represented by a figure eight, called an ?analemma?, can be approximated by the following formula: E = 9.87 * sin (2B) ? 7.53 * cos (B) ? 1.5 * sin (B) Where: B = 360 * (N-81) / 365 Where: N = day number, January 1 = day 1.