Swiss gold lever chronograph with pulsation Circa 1918

Unusual gold hunting cased chronograph by Vacheron & Constantin
–
A rare and unusual Swiss 18 carat gold hunting cased keyless lever chronograph pocket watch with pulsation scale, circa 1918. Jewelled lever movement, bimetallic compensation balance. Gold cuvette. White enamel dial with Arabic numerals, outer calculated pulsation ring, two sunken subsidiary dials for 30 minute register and constant seconds, later personalized with portraits of the original owners. Plain case, chronograph operated through a button in the band, hinged back. Case, cuvette, dial and movement signed, case and movement numbered.
–
Diameter: 50 mm
–
Signed: Vacheron & Constantin Genève