chronometer watch

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Object Type
Museum number: 1958,1201.1734
Escapement: pivoted detent
Description: SILVER-CASED SUBSIDIARY SECONDS POCKET-CHRONOMETER WITH PIVOTED DETENT ESCAPEMENT, FORMERLY WITH DUST-CAP. Chronometer watch. Pivoted detent escapement. Enamel dial. Silver case.
Producer name: Made by: George Edwarts; Case made by: JMK
Production date: 1880 (watch); 1903 (case)
Production place: Made in: London (England); Made in: Chester (Cheshire)
Dimensions: Diameter: 53.50 millimetres (case); Diameter: 44.50 millimetres (dial); Thickness: 20.40 millimetres
$Inscriptions
Curator's comments: Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990) Made by George Edwarts, 1903 Chronometer Signature: On the barrel bridge 'George Edwarts 005'. On the back plate 'CHRONOMETER MAKER TO THE ADMIRALTY LONDON'. Case: Open face silver case with the Chester hallmark for 1903 and the maker's mark J.M.K. surmounting a I. The inner dome numbered 005. The middle with fine reeding, the back engine-turned with an oval central cartouche and opening with a single fly spring, and a case catch and spring operated by a push-piece in the pendant. The pendant hallmarked and with the maker's mark CH. Diam. 53.5 mm, overall h. 20.4 mm. Dial and hands: Flat enamel dial with sunk central portion and subsidiary seconds, and inscribed CHRONOMETER in the upper half of the centre, secured directly to the front plate by three feet and pins. On the back of the dial in the enamel 86. Blued steel hands, all replacements. Movement: Ebauche marks 18 4 W.B., and 005, 005 also on the train bridge. Front plate diam. 46-6 mm; back plate diam. 41.2 mm; frame h. 8.2 mm. Frame: Full plate construction with four turned pillars,(1) the back plate retained by two blued steel screws and two pins. A detachable barrel bridge, no dial plate but the front plate recessed for all the under dial work. The movement hinge and case catch fitted on the front plate under the dial. There was once a dust cap, now missing. All the brass parts gilded, probably electro-gilded after acid etching. Fusee: Key wind fusee with the usual stop-work and maintaining power, the maintaining ratchet wheel steel. The setting-up-work fitted on the dial side of the front plate, in a shallow recess. The barrel arbor with an extended square on that end only. Going train: The usual layout and construction, the brass wheels burnished, the steel pinions and arbors well finished and polished. Jewelling: The pivots of the fourth and escape pinion arbors in pierced jewels, those of the balance staff in pierced jewels with endstones. Escapement: A form of pivoted detent escapement. The brass escape wheel left the full thickness, and locked by a triangular, clear sapphire, locking stone. The steel detent pivoted in the frame, the pivoting point planted well inside a tangent to the locked tooth. A blued steel spiral return spring acts by the free outer end resting against the detent. The passing spring also of blued steel pinned into a block set in the short detent tail. Banking provided by a strong brass pin in the path of the detent tail. The impulse roller with polished edge and notch, the impulse face leaning slightly towards a radius to the tip. Grained steel discharge roller with a jewel. Balance: Bimetallic two-armed balance with brass screws. Diam. of rim 17.4 mm, h. 1.62 mm. Balance spring: Blued steel spiral spring of 10½ turns, without an overcoil or terminal curve, pinned to a polished steel stud on the balance cock. 5 scratched on the underside of the cock. A polished steel index fitted on a boss concentric with the balance upper bearing. Going-train counts: Great wheel (fusee) 75 teeth Centre pinion 10 leaves, wheel 64 teeth, no crossings Third pinion 8 leaves, wheel 60 teeth, 5 arms Fourth pinion 10 leaves, wheel 75 teeth, 5 crossings Escape pinion 10 leaves, wheel 16 teeth, 4 crossings Beats per hour: 14,400 Motion work: Cannon pinion 14 leaves, brass minute pinion 12 leaves Hour wheel 48 teeth, minute wheel 42 teeth Provenance: Ilbert Collection; purchased by Ilbert from Malcolm Gardner in 1932. Note: (1) This is exceptionally late for a full plate movement; it is possibly re-cased.
Bibliographic references
Location: Not on display
Condition: Latest: 2 (2017); 3 (Oct 1995) Dust-cap missing.
Acquisition name
Previous owner
Acquisition date: 1958
Acquisition notes: Following the successful acquisition of the celebrated Ilbert collection of clocks (1958,1006 collection), prints and other related materials made possible by the generous donation of funds by Gilbert Edgar CBE Ilbert's watches were then acquired using funds provided by Gilbert Edgar, public donations and government funds.
Department: Britain, Europe and Prehistory
Registration number: 1958,1201.1734
Additional IDs: Previous owner/ex-collection number: CAI.1734 (Ilbert Collection); Previous owner/ex-collection number: M296 (Ilbert Ledger)

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