Fine French gold pocket chronometer with moon phases Circa 1840

Open faced pocket watch by Louis-Clément Breguet
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A fine French gold open faced pocket chronometer with moon phases, circa 1840. The watch features a gilded half plate movement, adorned with the signature Breguet, and incorporates a Louis Berthoud type pivoted detent chronometer escapement, a bimetallic compensation balance with three large keystone weights. These weights are secured with a gold screw and a platinum nut, along with an adjustment screw on either side. It also includes a blued steel helical spring, a ruby endstone, a fusee and chain with maintaining power, and a female winding sleeve. The silver engine turned dial has a satin finished chapter ring marked with black Roman numerals, an outer minute ring of similar finish, and blued steel hands. The minute hand features an open square at the base for setting purposes, while the subsidiary seconds display boasts a contrasting engine turned finish, and there is a large aperture for the ages and phases of the moon at 12 o’clock.
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The 18 carat gold case has an engine turned back, with the bezels and band further engine turned. Additionally, there is a recessed pusher beneath the bezel at 2 o’clock for adjusting the moon phases and a detachable polished gold cuvette signed by Breguet, complete with milled borders. The case displays a gold pendant and bow, while the back is signed and numbered B 873, featuring the case maker’s mark of J P with a star within a lozenge shaped cartouche, along with French hallmarks on the back and pendant.
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Diameter: 53 m
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Signed: Breguet
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The movement is running. The surfaces appear in generally good condition, with a few light scratches. The adjuster for moon phases is currently not operational. The dial has some light scuffs and a few scratches within the clouds beneath the aperture for moon phases. The engine turned case is generally clean, with a small abrasion on the inner edge of the bezel between 3 and 4 o’clock.
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French watchmaker, physicist, and inventor Louis (François) Clément Breguet was born on 22 December 1804 in Paris and is the grandson of Abraham-Louis Breguet. Louis was educated in Switzerland and took over the management of the family business from his father, Antoine-Louis Breguet, in 1833. On 17 May 1833, he married Eugénie Caroline Lassieur in Paris. She was the daughter of Jonas-Louis Lassieur, a nephew of Louis-Clément, and the granddaughter of Marie-Louise Breguet, the youngest sister of Abraham-Louis Breguet. Louis and Eugénie’s marriage produced three children: Louise, Antoine, and Madeleine. Eugénie’s father was Jonas-Louis Lassieur, a nephew of Louis-Clément and his father-in-law.