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|1010: Gents J.Sewill Chronometerwith Up/Down Display, Gold 18K, 1874|
Gross weight 108g
Accessories: newer key
Case: 16432, JWS, hallmark London 1874, gold 18K, mineral crystal, hinged double bezel, hinged back with guilloche pattern and free monogramm shield, hinged dust cover, D=49.5mm
Dial: enamel, inserted sunk sub second
Movement: 25511, J.Sewill, 30. Cornhill, Royal Exchange, London, calibre 18.5''', gold plated, 19 jewels, 4 visible screwed gold settings, key wind and set, fusee/chain, fusee with spring to maintain power during winding, chronometer escapement with spring detent 9000 P/h, bimetallic screw balance under diamond end-stone, unusual: the hairspring is helical with Philips-curve on the cock side, and spherical towards the balance
Condition: C1, D0, M0
Britten: John Sewill, 1871-1875, 30. Cornhill (London)
The company was still in business after 1970 with production and service of marine chronometers.
The summit of precision watch making
In early lever escapements the balance was continuously connected to the escapement wheel; nevertheless acceptable accuracy was obtained. But only the detached lever escapement allows the accuracy as we watch it today at certified chronometers.
It was called "detached" because the balance could almost freely oscillate - however not completely free: Twice per oscillation periode, balance and escapement wheel are shortly coupled via lever, disturbing the oscillation.
Still more detached is the chronometer escapement: It couples balance and whell only once per periode, and this much shorter than in the best lever escapement. Morover, only negligible mass is moved, if the escapement is designed with a spring detent after Earnshaw. Thus a "more detached" escapement is hard to imagine, and not for nothing this was the common escapement for marine chronometers.
Sold in Auction
High bid EUR 3960.00 (~CHF 4430.96)
Reserve EUR 2300.00 (~CHF 2573.54)
Not for Sale!
The watch presented here is not for sale. It was offered or sold as mentioned above a longer time ago. This archive is just a market overview and price guide, e.g. for evaluation of comparable watches. Moreover, images and descriptions can help for dating and checking the authenticity of watches.
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