A TRIBUTE TO PRECISION AND COMPLICATE...

Hotel Nogalhilton Geneve, Nov 11, 2001

LOT 30

Precision Timekeeper with 2 ComplicationsBreguet No. 1210, sold to Monsieur Labaume for 1,600 francs on February 4, 1808.Extremely rare, fine and important month-going center-seconds table regulator with true equation of time, annual Gregorian and Revolutionary calendars, accompanied by Breguet certificate.

CHF 180,000 - 220,000

USD 113,000 - 138,000

Sold: CHF 179,500

C. Mahogany, glazed on both sides and the front, rectangular cresting above molded cornice, veneered base.D. White enamel, Breguet numerals, minute divisions, gold Breguet equation hand, blued steel Breguet mean time hand, semicircular brass plate below with winding and calendar apertures. M. Rectangular with canted top corners, 153 mm x 176 mm, mounted to U-shaped brass frame, brass plates, turned cylindrical pillars with conical bases, double barrel, four-wheel train, pin-wheel escapement with jeweled pallets set on the back plate, steel and brass gridiron compensation pendulum beating half secondwith calibrated regulating knob and micrometric beat adjustment on the crutch, double spring suspension, leveling device mounted to the base. The annular wheel with engraved calendars is driven from one of the barrels via three wheels, the last of which is 20-tooth jump star wheel with a clutch for possibility of manual adjustment, the equation cam, fixed to the annular wheel, controls the equation hand via spring-loaded pivoted lever terminated with very nicely finished rolling cylinder to minmize the friction. This lever, via a fusee-like chain, is connected to the set of planetary wheels going to the canon pinion and the equation hand wheel.Signed on the dial and movement, movement numbered.Dim. Height 38 mm, width 23 mm.


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Grading System
Grade:
Case: 3

Good
Movement: 3 - 21*
Dial: 3 - 01

Notes

Table and wall "valet astronomiques" were sold both with and without cabinets. This one, as indicated in the Breguet registers, was sold without, and was made to be displayed under a glass dome. It is the only Breguet table "valet astronomique" known to date with equation of time and featuring both Gregorian and Revolutionary calendars.What is an Equation of Time?The equation of time was developed to explain and compensate for the discrepancy between true solar time and mean solar time. The true solar day is the length of time between one local noon, when the sun is highest, and the next. The length of this day is not always 24 hours, as the hours between sunrise and sunset are not always the same. The variable rate of the true solar day is due to two factors: 1) the Earth's rotation around the Sun is an irregular elliptical course and 2) the tilt of theEarth's rotation axis relative to its orbit around the Sun. Our yearly calendar that we rely on is based on an equal length of days throughout the year. The mean solar day (or time told by a watch or clock), 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. The true solar time and mean solar time coincide four times a year, April 16, June 14, September 1 and December 25. On these days, the Equation willqual zero. During the other 361 days, the equation of time must be used to indicate the difference between the two times, amounting to about 16 minutes at certain times of the 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 fourteen minutes and 20 seconds. These positive and negative values are the offset in the time of the local noon and those of sunrise and sunset. The equation of time is oftn represented by a figure 8, called an "analemma".The equation of time 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