- Museum number
- 1958,1201.989
- Description
-
MOVEMENT, DIAL AND DUST-CAP OF A LEVER WATCH.
.
Full-plate, fusee, Harrison's maintaining-power, ratchet-tooth lever-escapement, Earnshaw compensation balance, oversprung.
White enamel dial, 2-piece; hours I-XII, sunk subsidiary seconds.
Blued steel spade hands, seconds hand missing.
Gilt-brass dust-cap.
Case missing.
- Production date
- 1825-1835
- Dimensions
-
Diameter: 44.70 millimetres (dial)
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Diameter: 42.80 millimetres (dust-cap)
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Thickness: 12.80 millimetres
- $Inscriptions
-
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- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Thomas Earnshaw Junior
London, c. 1830
Movement of a ratchet tooth lever watch
Signature: On the barrel bridge 'Thos Earnshaw High Holborn' and on the back plate 'LONDON No 7104'.
Case: Missing.
Dial & hands: A flat dial with a sunk subsidiary seconds dial. The dial has hair-line cracks and is badly damaged and distorted where the hinge once was. Fired into the counter-enamel, in red, the word 'Crystal' with two un-deciphered words. Blued-steel spade pattern hour and minute hands, the seconds hand missing.
Dial-plate: Unmarked. Badly distorted when the movement was wrenched from its case.
Dust-cap: Stamped on the inside with the maker's mark 'WS' in cameo and the number 7104.
Movement
Ebauche Marks: None. There are four graver point marks on the front plate.
Frame: A full plate layout, the back plate supported by four turned pillars. The balance cock is finely engraved all over with foliate scrolls and has the number '04' scratched on the underside.
Fusee, Barrel and Mainspring:
Fusee: 43-turn fusee fusee with Harrison's maintaining power, with a steel maintaining ratchet wheel.
Barrel: internal diameter 16.0 mm, height 3.0 mm.
Mainspring: height 2.8 mm, thickness 0.25 mm.
Barrel Arbor: diameter 5.3 mm, not snailed.
Hooking: originally square but now round.
Train: All the wheels polished, the centre wheel solid, the third and fourth wheels with five crossings.
Jewelling: Jewelled bearings in screwed settings for the fourth wheel onwards except for the pallet pivots. A diamond endstone in the balance cock, a ruby endstone in a wedge in the potence.
Escapement: A right-angle layout ratchet tooth lever escapement with short lever, single roller and D-shaped impulse pin. The enclosed pallet stones have convex impulse and locking faces. The ungilded escape wheel has three crossings.
An equal impulse escapement.
No. of teeth embraced 32.
Balance & Spring: A bimetallic balance with brass timing and compensation screws, diameter 19.7, thickness 1.05 mm. A blued-steel flat spiral spring with 72 turns attached to a long polished steel stud on the back plate.
Means of Regulation: An index on the balance cock registers against a silver scale screwed to the back plate with 'Slow' and 'Fast' engraved on the back plate at each end.
Train Counts and Beat Rate:
Great wheel 70 (fusee)
Centre wheel 64 pinion 10
Third wheel 60 pinion 8
Fourth wheel 56 pinion 8
Escape wheel 15 pinion 7
Beat Rate: 14,400
Motion work: cannon pinion 12
minute wheel 48, minute pinion 14
hour wheel 42.
Winding System: Key wound.
Dimensions:
Movement: diameter 42.8 mm, height 13.0 mm, pillar height 3.2 mm.
Provenance: Formerly in the Ilbert Collection. Ilbert purchased this from Malcolm Gardner 21/5/1932.
- Location
- Not on display
- Condition
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Latest: 3 (2017)
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2 (1992)
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Dial badly damaged at XII.
- 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
- 1958,1201.989
- Additional IDs
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Previous owner/ex-collection number: CAI.0989 (Ilbert Collection)
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Previous owner/ex-collection number: M28 (Ilbert Ledger)