Gold Watch no. 744

Case: Dial: Movement: Provenance: 18?? - Potter, Geneve 2001 - Antiquorum, 11 Nov 2001, sold CHF 157,500 , "Albert H. Potter & Co. Geneva, No. 744, made circa 1885.Exceptional and certainly unique, 18K gold, hunting-cased, keyless, constant force chronometer escapement watch with self-starting and automatic balance-locking features. C. Four-body, "bassine et filets", solid, five-piece hinges, polished, double lift springs, gold glazed cuvette. D. White enamel, radial Roman numerals, outer minute ring, subsidiary sunk seconds, snap-on fit. Blued steel Breguet hands. M. 45,7 mm (20'''), nickel, "fausses côtes" and spotting decoration, 28 jewels, ingenious constant force escapement utilizing Potter's pivoted detent mechanism to wind and lock the spring-loaded pivoted impulse pawn, cut bimetallic compensation balance with goldemperature-adjusting screws and platinum screws for mean time adjustment, free-sprung blued steel helical balance spring, mechanism locking the balance when the watch is wound down, double barrel click, each with its own spring, the lever set with unusual self-loaded spring lever.Signed on dial and movement, case stamped with the same serial number.Diam. 54,6 mm. Notes This is clearly the masterpiece among all Potter's watches. It is the most unusual of the over 90 watches we know of, which is a strong statement considering that all his watches are exceptionally well-finished. The watch is magnificent in conception and execution, down to the last detail. In its constant force escapement, giving an impulse only in the center of the impulse pallet, the irregularities of unlocking are minimized by placing the unlocking pallet very close to the detent arbor, thusonsiderably reducing the momentum and making it less dependent on the pressure exerted by the escape wheel. Possibly the most unusual aspect is the self-starting feature. In unidirectional impulse escapements, one must jolt the watch to make it start. Not this one; it ingeniously employs the stopping device found in early perpetuelle watches which blocked the weight when fully wound; Potter, however, modified it to stop the balance. Furthermore, it does not lock it at an arbitrary point, but aftr one of the quarter screws, thus ensuring sufficient tension in the balance spring. Consequently, when the watch is wound and the balance released, the tension stored in the balance spring is enough to swing the balance and unlock the escape wheel, winding the hammer and giving an impulse to the balance. Although Henry Motel experimented with a similar arrangement, in his chronometers the locking was manual. There are numerous other small details that perhaps only a watchmaker can fully apprecite; the spotting on the plates done with an indexing machine which moves outward from the center, giving a sparkling appearance, the setting lever constructed in such a way that when the canon pinion tension is correctly set, backwards setting becomes impossible. The patented safety barrel is unique to Potter and not found anywhere else, the double click assures smooth winding and lessens the recoil somewhat, the high number of jewels, even on the barrel arbor, only confirms the impression of thmost careful finishing. "