Very fine French platinum and enamel chronometer Circa 1830

Chronometer with unusual and rare escapement by Bertot
–
A very fine French platinum and enamel open faced pocket chronometer, circa 1830. Bar movement, key winding, extremely rare chronometer escapement, a combination of a pivoted detent and a spring detent escapement with gold chronometer wheel and rubies, gold screw balance. Cuvette gilt or solid gold. White enamel with Roman hours and outer minute divisions, subsidiary seconds and filigree fleur-de-lys hands. Plain case, enamelled lion to the back. Case and cuvette with matching numbers, cuvette signed.
–
Diameter: 46 mm
–
Weight: 94 g
–
Signed: Bertot à Caen
–
This piece is an absolutely rare collector’s item, on the one hand, due to the platinum enamel case which is extremely rare for watches of this time, on the other hand, due to the completely unknown chronometer escapement in this version.