- Museum number
MOVEMENT, DIAL AND DUST-RING OF A LEVER WATCH.
Full-plate; fusee; Harrison's maintaining power; four-wheel train.
Ratchet-tooth lever escapement; bi-metallic compensation curb; plain steel three-arm balance.
Enamel dial; subsidiary seconds.
- Production date
Diameter: 47.50 millimetres (dial-plate)
Diameter: 45.90 millimetres (dust-ring)
Thickness: 15 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Finer & Nowland.(1)
London, c. 1840
Movement of a ratchet tooth lever watch with a Savage two-pin fork and roller action.
Signature: On the dial 'FINER & NOWLAND LONDON' and on the back plate 'Finer & Nowland 4102', on the barrel bridge 'LONDON'
Case: Missing, the movement was hinged to the case at XII.
Dial & Hands: Flat dial with a subsidiary seconds dial. Fine cracks in the dial. The hands are missing.
Dial-plate: Standard pattern without marks.
Dust-cap: A gilded edge ring retained by two dog screws.
Ebauche Marks: 20 6 also, inside the front plate, '41 C2 C2'.
Frame: Full plate layout with the back plate supported by four turned pillars. The potence has a straight moulded foot. The balance cock is engraved all over with foliate scrolls. A blued-steel balance protection post is mounted in the front plate.
Fusee, Barrel and Mainspring:
Fusee: six-turn fusee with Harrison's maintaining power and a steel maintaining ratchet wheel.
Barrel: Internal diameter 18.7 mm, height 4.0 mm.
Mainspring: height 3.6 mm, thickness 0.25 mm,(2) not original.
Barrel Arbor: diameter 5.9 mm, not snailed.
Hooking: originally square but now round.
Train: Gilded brass wheels, the centre wheel solid, the third and fourth wheels with five crossings.
Jewelling: Jewelled bearings for the rear fourth wheel pivot, the escape wheel and the balance pivots. Ruby endstones for the escapement, that in the potence in a wedge, otherwise the jewels are in screwed settings.
Escapement: An acute-angle layout ratchet tooth lever escapement with a Savage two-pin fork and roller action. The pins in the roller are gold. There is slight wear in the notches. The enclosed pallet stones are flat on the impulse and locking faces. The brass escape wheel has three crossings.
A mixed impulse escapement.
Number of teeth embraced 32.
Balance & Spring: A rounded-rim polished steel three-arm balance, diameter 22.4 mm, thickness 1.00 mm. Blued-steel flat spiral spring with seven turns attached to a polished steel stud screwed to the back plate.
Means of Regulation: An index registers against an applied silver scale screwed to the back plate with 'Slow' and 'Fast' engraved at the ends on the back plate.
Temperature Compensation: A Breguet type bimetallic curb screwed to the regulator index has a single curb pin at the end which operates in conjunction with the fixed curb pin in the index. There is a screw in the bimetallic curb at the folded end to limit the movement of the free end.
Train Counts and Beat Rate:
Great wheel 60 (fusee)
Centre wheel 64 pinion 12
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.
Movement: diameter 47.4 mm, height 15.4 mm, pillar height 4.3 mm.
Provenance: Formerly in the Ilbert Collection.
(1) Thomas Finer and Thomas Nowland of 48 High Holborn, London.
(2) Although the mainspring is not the original it is of interest in being of an unusual cross section. The outside face is virtually flat having only a very slight curvature towards the edges. However the inside face is more highly curved. At the centre the spring is 0.25 mm, in thickness but at the edges it is only 0.18 mm. Although this leads to less friction between the surfaces as long as lubricant is present, the highly localised pressure tends to break down the lubricant, especially if anything other than a grease is used.
- Not on display
Latest: 3 (2017)
- 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.0951 (Ilbert Collection)