Rare French double dialled 24 hour world time lever watch Circa 1887

Pink gold keyless lever watch by Bernard Callier
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A very rare French pink gold double dialled 24 hour world time keyless lever watch with an enamelled map of the northern hemisphere, circa 1887. This watch features a gilded movement with a lever escapement, 19 jewels, and a bimetallic compensation balance. The case is made of pink gold and features a plain polished hinged back that opens to reveal the rear dial, which is numbered 2325.–
The watch has two dials: the front dial is white enamel with a 24 hour chapter ring divided into concentric 12 hour periods in red and black. The dial’s centre displays a polychrome enamel rendition of the world, with the Northern Hemisphere on the outer edge and the Southern Hemisphere at the centre. The watch is equipped with blued steel moon hands and a central gilt hand for setting the designated longitude. The concealed back dial is also white enamel and includes an outer minute ring with Arabic five minute divisions, a subsidiary seconds display, and additional features for regulation. The minutes and seconds run counterclockwise. A recessed plaque is inscribed with Montre Géographique Sans Calcul donnant les longitudes, les latitudes, et les heures de tous les points de la terre, and it is signed and dated Callier, Horloger de l’Observatoire, Fournisseur de la Marine de l’Etat, Paris, 1887.
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This unique and distinctive watch features a front dial displaying lines of longitude and latitude, allowing it to show the current time anywhere in the world. The central gold hand indicates the time in the user’s current location, while the time in other locations can be determined by tracing their nearest line of longitude to the chapter ring.
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Diameter: 58.5 mm
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Signed: Callier, Horloger de l’Observatoire Fournisseur de la Marine de l’Etat, Paris 1887
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The movement is running smoothly, and the handset is well adjusted. Both dials are in good overall condition. The back dial has a small residue on the upper right side of the subsidiary Montre Géographique plaque dial, along with a light scratch near the edge. The case shows signs of light polishing and has a few scratches.
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Bernard Callier, French watchmaker
Bernard Agnan (Aignan) Callier was born on January 20, 1821, in Aubigny, Cher (now Aubigny-sur-Nère), France. He began his career as a watch and chronometer maker in Gien and later established himself on Quai St. Michel in Paris. In 1867, Callier was awarded a gold medal at the Paris Exhibition. In 1870, he acquired the workshop of Joseph Thaddäus Winnerl. By 1879, he had developed a new compensation balance for chronometers and was appointed Horloger de l’Observatoire in 1880. On July 20, 1893, he was honoured as a Chevalier of the Legion of Honour. Eventually, Emmanuel Boudeaud joined the Boudeaud company at 50 Boulevard de Port Royal, succeeding Bernard Callier. Bernard Callier passed away on December 15, 1908, in Neuilly, near Paris.