Magnificent Swiss gold and enamel duplex pocket watch Circa 1810

Gold duplex with dead centre seconds
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A magnificent Swiss 18 carat gold and painted on enamel pocket watch, circa 1810. With a dual calendar, equation of time indication, dead centre seconds with stop feature, the early type double wheel duplex escapement and large seconds beating balance wheel.
A polished case, the back decorated with a finely painted enamel scene of a Roman centurion and a lady in a landscape within an arch, royal blue ground with gold paillon pillars and vari coloured paillon flower garlands, gold paillon profile head below, outer sprig border.
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White enamel dial with offset radial Roman numerals, outer minutes and seconds divisions and Arabic fifteen second numerals, concentric with the equation of time sector, subsidiary dials above for the date and months with their respective number of days. Gold Breguet hands, gold sun hand for the equation of time. Matte gilt full plate movement, cylindrical pillars, fusee and chain with maintaining power, double wheel duplex escapement, large seconds beating three arm brass balance, flat balance spring, finely pierced and chased continental balance cock with polished steel endplate, silvered regulation dial, spring for the stop feature on the backplate with lever protruding from the dial plate.
Dial and movement signed, case and movement numbered.
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Diameter: 59 mm
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Signed: Meuron & Comp.  Swiss
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EQUATION OF TIME With this type of Equation of Time display, the equation hand is concentric with the minute hand. The difference between the meantime and the solar time is shown by the Sun hand which revolves, following or preceding the regular minute hand of the meantime. The equation of time 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 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.
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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 to over 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 14 minutes and 20 seconds. Pocket watches with a true equation of time indication using an irregular cam and a separate hand are exceedingly rare with only very few examples known. The present watch is particularly interesting because it also incorporates an early form of double wheel duplex escapement which impulses the balance so that it beats at one second intervals, thereby allowing the inclusion of a deadbeat center seconds hand.