French gold quarter repeater with grande sonnerie Circa 1809

Gold open faced pocket watch by Mugnier
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A very fine and extremely rare French Empire, 18K gold, two-train quarter repeating grande sonnerie clockwatch with Robin detent lever escapement, hallmarks for circa 1789-1809.
Gilt brass movement, half-plate, standing barrel, 10 jewels, Robin detent lever escapement with jewelled impulse pallet, the escape wheel and lever with jewelled pivots and polished steel endplates, three-arm gold balance wheel, the top pivot with pare-chute, blued steel flat balance spring with bimetallic compensation curb fixed to the index regulator, the striking and repeating train with fixed going barrel, striking the hours and quarters at each quarter and at will by depressing a button in the pendant, strike/non-strike lever in the band.
Case with mastermark for Amy Gros (AG), polished. Gilt metal cuvette.
White enamel dial with Breguet numerals, outer minute track, subsidiary seconds with Arabic 60-second numerals. Blued steel Breguet hands.
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Diameter: 54 mm
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Signed: Mugnier Horloger de L’Empereur et Roi
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This watch, very much in the style of Breguet, is by Charles Mugnier the younger, watchmaker to the Emperor Napoleon I, and later to S.A.R. Monsieur, the brother of Louis XVIII. He worked in Paris on the Rue Neuve des Petits Champs 1807-1823. Copied Breguet’s ‘sousenption. Mugnier served his apprenticeship under Abraham Louis Breguet, and alongside his master and Charles Oudin (another pupil of Breguet?s), was the only maker capable of executing a watch of such good quality, which can be compared with most of the best watches by Breguet, although it was made from a blank of entirely original design which was used by Breguet. Moreover, Mugnier used for this watch Robin?s detent lever escapement, which he only used for his top quality production such as the wonderful perpetuelles, considered worldwide as even better than those made by his master, Invented by Robin in 1791, the detent lever escapement, compared to regular spring or pivoted detent escapements, is less sensible to inertia.