Swiss 18 carat gold astronomical verge watch Circa 1800

Technically significant watch with equation of time
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A technically significant astronomical verge watch with calendar and equation of time. The movement was made by J. Robert & Fils, Courvoisier & Cie in La Chaux-de-Fonds, Switzerland, circa 1800. This watch features a numbered plain case crafted from 18 carat gold and bears a hallmark PIG with a crown, manufactured by Courvoisier Frères around 1840. The white enamel face features a decentralised time display at 6 o’clock, a display of the date at 3 o’clock, month and month length at 9 o’clock and a kidney shaped window for displaying the length of the day depending on the season at 12 o’clock and gold Breguet hands. The numbered movement is equipped with a Courvoisier Frères verge escapement.
The dial and movement are signed, probably at a later date (around 1843).
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Diameter: 54.5 mm
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Weight: 103 g
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Signed: Courvoisier Frères
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Equation: In astronomy, the difference between mean solar time and true solar time is called the equation of time. The equation of time is different every day and varies between -14.59 and +16.15 minutes. It is indicated on the dials by a hand or a cutout. Pocket watches with an equation of time are extremely rare among astronomical pocket watches. Only a few pieces are known to exist. The design on offer here, with the kidney shaped window, was invented by Courvoisier.
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Courvoisier
The name Courvoisier represents one of Switzerland’s most distinguished watchmaking legacies, spanning over 200 years and reaching the courts of European emperors. While separate from the famous cognac house, the family was equally influential in horology.

The brand’s roots trace back to Josué Robert, a master watchmaker who received the first watchmaking patent from the King of Prussia in 1725.

• 1781: Louis Courvoisier, Robert’s son-in-law, joined the firm.
• 1787: The company rebranded as J. Robert & Fils, Courvoisier & Cie, signalling Courvoisier’s rising influence.
• 1811: After internal tensions, Louis took full control, renaming the firm Courvoisier & Cie.