- Museum number
MOVEMENT AND DUST-CAP OF A LEVER WATCH.
Full-plate; fusee; Harrison's maintaining power; ratchet-tooth lever escapement.
Gilt brass dust cap.
- Production date
Diameter: 48.30 millimetres (dial-plate)
Diameter: 44.70 millimetres (dust-cap)
Thickness: 13.40 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Charles Frodsham
London, c. 1860
Movement of a ratchet tooth lever watch
Signature: On the barrel bridge 'Arnold C Frodsham 94 Strand 100511' (1)
Dial & Hands: Missing.
Dial-plate: No dial-plate intended.
Dust-cap: Punched WS in an oval cameo and scratched '51' on the inside edge and 'V' inside the barrel bulge .
Ebauche marks: 20 3 10051
Frame: Full plate layout, with four turned pillars supporting the back plate. The balance cock is engraved with foliate scrolls. Numbered 51 under the barrel bridge and 10051 on the inside of the back plate. The number 51 is also inscribed beneath the balance cock.
Fusee, Barrel and Mainspring:
Fusee; four-turn fusee with Harrison's maintaining power, the maintaining ratchet of steel.
Barrel: flanged at the cap end, internal diameter 17.5 mm, pillar height 3.7 mm.
Mainspring: height 3.5 mm, thickness 0.23 mm.
Barrel Arbor: diameter 5.9 mm.
Train: All the wheels gilded, the centre wheel solid, the third and fourth wheels with five crossings.
Jewelling: Jewelled bearings for the third wheel onwards. All the jewels in the front plate are rubbed in with the exception of the escape wheel jewel which along with the jewels in the back plate are in screwed settings. Ruby endstones for the escape wheel. The potence with a ruby endstone in a wedge and the endstone in the balance cock a diamond. The lever holes are not jewelled.
Escapement: A right-angle layout ratchet tooth lever escapement with short lever, single roller and round impulse pin. The enclosed pallet stones have convex impulse and locking faces with a chamfer on the exit edge of the exit pallet. A polished brass escape wheel with three crossings.
An equal impulse escapement.
No. of teeth embraced 32.
Balance & Spring: A split bimetallic balance with brass compensation and quarter screws, balance diameter 21.0 mm, thickness 1.4 mm. Blued-steel flat spiral spring with 93 turns attached to a polished steel stud mounted on the back plate.
Means of Regulation: An index mounted on the balance cock registers against a divided silver scale applied to the back plate, with 'SLOW' and 'FAST' engraved on the back plate. A slot in the tip of the balance cock table allows the cranked index arm to move and the slot edges form bankings preventing the index from being moved beyond the scale.
Train Counts and Beat Rate
Great wheel 70 (fusee)
Centre wheel 64 pinion 10
Third wheel 60 pinion 8
Fourth wheel 63 pinion 8
Escape wheel 15 pinion 7
Beat rate: 16,200
Motion work: Cannon pinion 12. The minute wheel and pinion and the hour wheel are missing.
Winding System: Key wound.
Movement: diameter 48.3 mm, height 13.3 mm, pillar height 3.7mm.
Provenance: Formerly in the Ilbert Collection. Purchased by Ilbert in Ealing 10/12/1931.
(1) This would appear to be a mistake, as the firm was at 84 Strand. The number also appears to be wrongly engraved since it does not agree with the numbers on the other parts of the movement. It is somewhat surprising that these two mistakes, which must have been noticed at the time, were not rectified by replacing the barrel bridge. It is of course possible that this watch is a fake but nothing about it supports this view. If the watch number were 10051 as it appears in various parts of the watch apart from on the back plate, it would fit in the sequence which includes watch numbers 9737 and 12867, in cases hallmarked 1858 and 1862 respectively, see Mercer, The Frodshams p. 245.
- 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.0922 (Ilbert Collection)
Previous owner/ex-collection number: L143 (Ilbert Ledger)