- Museum number
POCKET-CHRONOMETER MOVEMENT WITH SPRING DETENT ESCAPEMENT.
Spring detent escapement; chronometer escapement applied 1834.
- Production date
Diameter: 45.70 millimetres (dial)
Diameter: 41.80 millimetres (dust-cap)
Thickness: 15.50 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by Ellicott, 1823-4
Signature: On back plate 'Ellicott LONDON 10078'.
On the balance cock 'Chronometer Escapement applied by Brockbanks & Atkins 1834'.
Dial and hands: Flat enamel dial, damaged, with Roman hour numerals and subsidiary seconds dial, signed below the figure XII, 'ELLICOTT Royal Exchange'.
Gold minute and hour hands, seconds hand missing.
Ebauche marks 166.
Dial plate diam. 46.0 mm; front plate diam. 43.9 mm; back plate diam. 39.0 mm; frame h. 6.6 mm.
Frame: Full plate with four turned pillars, the back plate retained by pins, detachable barrel bridge. A dust ring retained by two dog screws at the edge of the back plate, one missing. The dial plate carrying the movement hinge fixed to the front plate by three short feet and pins, scratched on the front 'Wident' and faintly 'Ellicott'. The case catch and spring screwed to the front plate under the dial. The frame dust ring and dial plate gilded.
Fusee: Keywind fusee with normal stop-work and maintaining power, the maintaining ratchet wheel steel. The barrel arbor with an extended square at both ends, the blued steel setting-up ratchet wheel and click mounted on the barrel bridge. The barrel with a flange at the cover end. The setting-up click return spring and screw missing from the barrel bridge.
Going train: Brass wheels gilded, the steel pinions, pivots, arbors and undercuts polished.
Jewelling: The lower pivot of the fourth arbor in a pierced jewel. The pivots of the escape pinion arbor and balance staff in pierced jewels with endstones. Diamond endstone in a blued steel ring on the balance cock.
Escapement: The original escapement, replaced by Brockbanks and Atkins, was presumably either a cylinder or a duplex. The escapement now fitted is an Earnshaw type of detent escapement with brass escape wheel sunk out on the upper side to leave only the teeth standing proud of the rim. The wrecked dovetailed detent was set in a gilded brass cock with integral banking. Both the impulse and discharge rollers are jewelled, the former with its jewel leaning slightly forwards. Both are grained, being unpolished on any surface. The discharge roller has a flat for adjusting.
Balance: Bimetallic two-armed balance, the steel parts blued, with steel quarter and brass compensation screws, two of the quarter screws in the wrong positions. Diam. of rim 18.0 mm, h. 1.58 mm.
Balance spring: Blued steel spiral spring of 7¾ open turns, free sprung to an overhanging polished steel stud screwed to the back plate.
Balance cock: The original balance cock probably fitted better against the end of the barrel bridge, and must have carried an index with tail passing over the back plate. The engraved indications for slow and fast remain.
Great wheel (fusee) 72 teeth
Centre pinion 12 leaves, wheel 64 teeth, no crossings
Third pinion 8 leaves, wheel 60 teeth, 6 arms
Fourth pinion 8 leaves, wheel 80 teeth, 6 arms
Escape pinion 8 leaves, wheel 15 teeth, 3 arms
Beats per hour: 18,000
Cannon pinion 12 leaves, minute pinion 14 leaves
Hour wheel 42 teeth, minute wheel 48 teeth
Provenance: Ilbert Collection; purchased by Ilbert from Malcolm Gardner in 1933.
- Not on display
Latest: 3 (2017)
4 (Oct 1995) Seconds hand missing. Dial badly damaged between VIII and X
- 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.1596 (Ilbert Collection)
Previous owner/ex-collection number: N72 (Ilbert Ledger)