- Museum number
GOLD-FILLED CASED SUBSIDIARY SECONDS POCKET-CHRONOMETER WITH PIVOTED DETENT ESCAPEMENT AND KEYLESS WINDING.
Pivoted detent escapement.
Later gold filled case.
- Production date
Diameter: 55.70 millimetres (case)
Diameter: 44.20 millimetres (dial)
Thickness: 18.30 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by Jules Jürgensen, c. 1870
Signature: On the bridges 'Jules Jürgensen Copenhagen No 12422'. On the dial 'Jules Jürgensen Copenhagen'.(1)
Case: Later metal case, the front bezel and back hinged to the middle opposite the pendant. All three decorated with an engraved or embossed design, and with engine-turned decoration on the back. The cuvette glazed. The movement fitted into a metal ring fitting tight in the case. Diam. 55.6 mm, h. over glass 18.4 mm
The inside of the back marked ' C.W.C. Co. Trade Mark ' and '596766'. The middle marked '6766' and 'Pat'd Dec 7 86'.
The pendant bow extending inside the hollow pendant and arranged to operate a sleeve for the hand set when turned to rest against the front or back of the case.
Dial and hands: Finely marked flat enamel dial with sunk subsidiary seconds, held friction tight in a white metal ring snapping onto the edge of the front plate, and with one positioning peg. Blued steel hands, the seconds hand not original.
Ebauche marks: stamped on the front plate under the dial 'Jules Jürgensen of Copenhagen 12422', also the scratched number 66724 over the letters of the inscription.
Front plate diam. 45.2 mm; bridge overall diam. 43.9 mm; frame th. 7.0 mm; front plate h. 3.4 mm.
Frame: Open bridge construction built up on a massive front plate with turned or milled recesses for the motion and keyless work and for the going train and escapement parts. The frame made of an alloy of nickel brass, the surfaces finished in the most careful and refined way with spotting under the dial and fine snailing on the visible surfaces at the back.
Going barrel: Of the hanging barrel type and fitted with Geneva stop-work, the Maltese cross missing.
Going train: The high numbers of the pinions give an indication of the quality of the train. The crossings of the gilded brass wheels very carefully filed with a rounded bevel on the upper surfaces, the steel parts well finished and polished.
Jewelling: The centre arbor rear pivot, and those of the third and fourth arbors in pierced jewels with curved faces against the pivot shoulders. All the pivots of the escapement arbors in pierced jewels with endstones. The detent and escape wheel upper endstones set in red gold plates.
Escapement: Pivoted detent, the gold escape wheel very finely crossed out and finished. The pivoted detent with spiral return spring, half-round locking stone and gold passing spring held away from the body of the detent by the short horn with its end formed at right angles to the rest. The centre line of the detent planted outside a tangent to the locked tooth, and locking on the second tooth after the one which has just given impulse. The detent banked by the extending locking stone passing into an eccentric hole in a steel plate set in the front plate. Jewelled impulse roller, the jewel set with its impulse face leaning slightly towards a radial from the centre to the tip. The discharge roller a later replacement made of steel.
Balance: Bimetallic two-armed balance with gold screws, the steel parts blued. The arms join the rim midway between the top and bottom of the rim. Diam. 20 mm, h. 1.6 mm.
Balance spring: Blued steel spiral spring of 12½ open coils and with an overcoil and terminal curve having a reversed curve. A steel finger piece is attached to the end of the last turn of spring, before the overcoil, by a brass pin clamping the spring in a hole. This works in conjunction with an amplitude limiting device. Round brass collet; polished steel stud held by 2 screws on the balance cock. Polished steel index with a long tail passing over a vernier scale on the centre and third bridge.
Amplitude limiting device: A pin (now missing) standing up on one balance arm passes between two prongs set in a block and pointing down from the underside of the balance cock. The finger piece carried on the balance spring and described earlier is carried outwards by the expansion of the balance spring and is so arranged that at a certain amplitude it closes the gap between the two prongs before the pin on the balance arrives to pass through. Being unable to pass, the balance is thus prevented from attaining a larger amplitude.
Keyless work: Swiss sliding-pinion keyless work with massive steel winding wheels. The hand set operated by moving the pendant bow as described under Case details. In either position a pair of levers is set in motion by a sleeve in the pendant tube to move the sliding pinion into engagement with the first of two intermediate hand-set wheels transmitting motion to the minute wheel.
Great wheel (going barrel) 96 teeth
Centre pinion 12 leaves, wheel 96 teeth, 5 arms
Third pinion 12 leaves, wheel 90 teeth, 5 arms
Four pinion 12 leaves, wheel 80 teeth, 5 arms
Escape pinion 8 leaves, wheel 15 teeth, 5 arms
Beats per hour: 18,000
Cannon pinion 16 leaves, minute pinion 9 leaves
Hour wheel 48 teeth, minute wheel 36 teeth
First winding pinion or crown wheel 18 winding teeth, 12 ratchet teeth
Intermediate winding wheel 38 spur teeth and 38 bevel teeth
Barrel ratchet wheel 40 teeth
Sliding pinion 12 ratchet teeth and 22 bevel teeth for hand setting
First intermediate hand-set wheel 25 teeth
Second intermediate hand-set wheel 29 teeth
Provenance: Ilbert collection. Purchased by Ilbert from Malcolm Gardner in 1932.
(1) Although signed 'Jules Jürgensen, Copenhagen', the watch would have been made at Le Locle in Switzerland where Jules Jürgensen spent most of his life. As far as the author knows, all the very high-class watches made by Jules Jürgensen were signed in this way; see Chamberlain 1941, pp. 413-15. A similar watch compete in its original silver case, the movement numbered 14424, is in the Museum of La Chaux-de-Fonds, Switzerland.
- Not on display
Latest: 3 (Oct 1995)
3 (Oct 1995)
- Acquisition date
- 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.
- Britain, Europe and Prehistory
- Registration number
- Additional IDs
Previous owner/ex-collection number: CAI.1728 (Ilbert Collection)
Previous owner/ex-collection number: L202 (Ilbert Ledger)