Rare Swiss gold watch with 30-hour power reserve Circa 1920

Observatory chronometer by Vacheron & Constantin
–
A rare and highly interesting Swiss observatory chronometer/test chronometer with a 30-hour power reserve indicator, circa 1920. This watch was completed in August 1920 and sold on April 18, 1939, to the Etablissements Edmond Jaeger, Paris (France).
Extremely rare chronometer movement, 21 jewels, wolf’s toothing, special fine adjusting device, index regulator with patented swan-neck spring and micrometric screw, eight adjustments, movement number 388237. Very well-preserved enamel dial with Breguet-style radial hours, outer minutes track, subsidiary dial for the seconds, extremely rare power reserve indication, and blued steel hands. Polished 18K gold à-goutte case, case number 247280. Dial, case and movement signed. Accompanied by a copy of the invention patent and by The Extract from the Archives, dated November 10, 1994, that mentioned that this watch was made in 1920 and sold in 1939.
–
Diameter: 50 mm
–
Weight: 83 g
–
Signed: Vacheron & Constantin, Genève Suisse
–
This extremely rare chronometer was not intended for sale but for observatory testing purposes. According to the archives, it was made in 1920 and was not sold until 1939. In the archive documents, the movement is marked Development Resort.