Swiss gold chronometer with Guillaume balance Circa 1920

Gold keyless hunting cased watch 
–
A very fine Swiss, 18K gold hunting cased, keyless lever pocket chronometer with Guillaume balance, circa 1920. Massive bassine, entirely engine-turned with a geometric pattern, the front cover with a vacant cartouche. Hinged gold cuvette inscribed Bulletin de 1ere Classe de l’Observatoire Astronomique de Neuchatel.

White enamel dial with Breguet numerals, outer minute track, subsidiary seconds. Gold spade hands. Rhodium-plated movement, Geneva striping decoration, 21 jewels, straight-line lever escapement, cut Guillaume balance, blued steel Breguet balance spring with swan-neck micrometre regulator. Dial, case and movement signed.
–
Diameter: 51 mm
–
Signed: Ulysse Nardin  Locle & Genève