20,700 CHF
Brosse à Bordeaux (France), No 24, circa 1830. Very fine and unusual 2-day marine chrono-meter of special construction. Two-body, mahogany, top with sliding panel to reveal the dial, fixed brass handles, lock in front, bracket for key in the left rear corner. Gimbaled bowl with poising weight at the bottom, threaded glazed bezel. Silvered, champlevé Roman numerals, outer minute track, subsidiary seconds. Blued steel "spade" hands. 96 mm, brass, 3/4-plate, going barrel, Earnshaw spring detent chronometer escapement, unusual cut bimetallic compensation balance with brass arm and bimetallic rims screwed to the arm bracket, Earnshaw-type trapezoidal sliding temperature weights, two mean-time screws, blued steel free-sprung helical balance spring with terminal curves fastened to adjustable stud. Signed on the dial. Dim. 20 x 20 x 18 cm. Notes This is one of only three Brosse marine chronometers known. Each one is highly unusual. The one sold by Antiquorum on April 12, 1997 (lot 231), features the most unusual constant force escapement. The present one and the one in the Musée des Arts et Métiers are very similar, the only significant difference being that this one is equipped with an Earnshaw spring detent and the one at the Musée des Arts et Métiers with Arnold’s spring detent escapement. All three are with going barrels. The concept of timepieces with just going barrel appeared in France in late 1670 or early 1680. The invention by Huygens in 1675 of the balance spring,
Auctioneer:
Antiquorum
Date:
2002-10-19