French watch with chronometer escapement Circa 1820

Silver  watch with a large auxiliary seconds indicator
–
A French pocket chronometer  with spring detent escapement according to Thomas Earnshaw, circa 1820.
A silver case and white enamel dial, 2/3 plate movement, large three-arm brass balance, hack feature.

The balance of this pocket chronometer has a diameter of 21 mm! The dial is fitted with a large auxiliary seconds indicator with hack mechanism and shows that the maker of the watch laid great value on accuracy. Not many movements by Brosse in Bordeaux still remain – the majority of them is kept by the Conservatoire National des Arts et Métiers in Paris. The small number of pendulum clocks, marine chronometers and pocket watches are often fitted with unusual custom-made mechanisms.
–
Diameter:  61 mm   Weight: 154 g
–
Signed: Brosse à Bordeaux