French rare 18K gold skeletonized verge watch Circa 1780

Gold skeletonized verge watch by Berthoud
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A very fine and rare French 18K gold and gemstone-set open faced skeletonized verge pocket watch, circa 1780. glazed on both sides,
Engraved case, glazed on both sides, gemstone-set bezels, chased and engraved à trois couleurs band and a large lateral hinge. Signed white enamel paste-set dial with radial Roman hours, Arabic minutes and paste-set pierced hands. Hand-engraved fire gilt skeletonized movement, moulded pillars, chain and fusee, a regulation device for a flat balance spring, verge escapement, three-arm steel balance.
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Diameter: 41 mm
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Weight: 50 g
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Signed: Berthoud à Paris
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Ferdinand Berthoud was born on March 19, 1727, in Plancemont near Neuchâtel, Switzerland. His father was a bricklayer, carpenter, architect and lawyer. He had three brothers who also worked as watchmakers Jean-Henry Berthoud, Jean-Jacques Berthoud and Pierre Berthoud. At the age of fourteen, Ferdinand began an apprenticeship with his brother Jean-Henry, who worked as a watchmaker in Couvet. He stayed there for four years until he went to Paris in April 1745. He opened a studio on Rue Harlay. His start in the French capital was made easier because his brother Jean-Jacques had lived there since 1742. Through his work, he drew the attention of Julien Le Roy, with whom he then worked for a long time. From 1756 he specialized in the construction of precision clocks and, around 1771, independently developed the chronometer escapement with rocker and spring winding. Abraham Louis Breguet probably also worked for him. Ferdinand Berthoud was purveyor to King Louis XV and his grandson and successor Louis XVI. In 1763 and 1766, he was sent to London to find out the secrets of Harrison’s H4. His main merit is the construction of the French marine chronometer. In 1770 he was appointed ‘Horloger mécanicien du Roi et de la Marine’ (watchmaker of the king and the navy). Later he became a member of the ‘Institut de France’ and the ‘Royal Society’. On July 17, 1804, he was appointed ‘Knight of the Legion of Honor’.
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Ferdinand Berthoud was married twice, first to Elisabeth-Henriette Chatry de la Fosse and later to Marie-Adélaïde Dumoustier. Marie-Adélaïde Dumoustier was a daughter of Gabriel-Etienne-René Dumoustier (1730-1802), an uncle of Elisabeth-Henriette Chatry de la Fosse. He died childless after a short illness on June 20, 1807, in Groslay near Paris. In Paris, a primary school is named after Ferdinand Berthoud, as are Couvet, Argenteuil, Groslay and Besançon.