- Museum number
MOVEMENT AND DIAL OF A LEVER WATCH WITH CENTRE-SECONDS.
3/4-plate, fusee, Harrison's maintaining-power, Chalfont rocking-bar keyless-work, 3rd. and 4th. wheels have separate bridge in back-plate, ratchet-tooth lever-escapement, Earnshaw compensation balance, Breguet overcoil.
White enamel dial; hours I-XII, minutes 5-60, 1/4 seconds.
Gold spade hour and minute hands; blued steel centre-seconds hand.
- Production date
Diameter: 40.70 millimetres (back-plate)
Diameter: 44 millimetres (dial)
Curvature: 11 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 V (Unpublished manuscript)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. 1864.(1)
Movement of a centre-seconds ratchet tooth lever watch
Signature: 'CHAs FRODSHAM 84, STRAND LONDON 02317 AD Fmsz'(2) on the dial and 'Chas. Frodsham, 84, Strand, LONDON. No. 02317. AD,, Fmsz,,' on the back plate.
Dial & Hands: Flat dial, the minute circle with 3-second graduations and numbered 0-60 at 5-second intervals in Arabic. The number '17' fired into the counter-enamel. Gold spade-pattern hour and minute hands and a blued-steel centre seconds hand with a polished centre.
Dial-plate: None intended, the dial is pinned directly to the front plate.
Dust-cap: None intended.
Ebauche Marks: I.P
Frame: A three-quarter plate layout, the back plate supported by three turned pillars and secured by screws. There is a separate plate screwed to the back plate to provide a bearing for the third pinion and fourth wheel pivots. A combined cock for the escape wheel and pallets. The balance cock is plain.
Fusee, Barrel and Mainspring:
Fusee: 43-turn fusee with Harrison's maintaining power and with a steel maintaining ratchet wheel.
Barrel: internal diameter 15.8 mm, height 2.5 mm a fine lip at the cap end. Mainspring: height 2.35 mm, thickness 0.25 mm.
Barrel Arbor: diameter 5.3 mm, snailed.
Train: A high quality train with gilded brass wheels and high-count pinions. The centre, third and fourth wheels have six crossings. The second wheel is off-set from the centre and recessed into the front plate. It also carries the motion work beneath the dial for the hour and minute hands. The fourth wheel is planted at the centre of the movement and recessed into the front plate. The third wheel and fourth pinion run above the balance in a raised plate screwed to outside of the back plate.
Jewelling: Jewelled bearings from the fusee onwards with the exception of the fusee and fourth wheel in the front plate. The jewels are all bombé. Most unusually there is an endstone for the fourth wheel in the back plate bridge. The escapement with ruby endstones throughout except for a diamond in the balance cock. All of the jewels are in screwed settings except for the second wheel jewel in the front plate, which is rubbed in.
Escapement: An obtuse-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 pallet staff has one pivot broken. A most delicate polished brass escape wheel with three crossings.
An equal impulse escapement.
No. of teeth embraced 32.
Balance: A split bimetallic balance with gold compensation screws and quarter nuts. The balance diameter 17.9 mm, thickness 1.5 mm. Blued-steel flat spiral spring with 14 turns, pinned to a rectangular polished steel collet on the balance staff, and with a terminal curve pinned to a polished steel stud screwed to the balance cock. One balance pivot is broken.
Means of Regulation: An index on the balance cock registers against a divided scale with 'S' and 'F' with a fleur-de-lys between, engraved on the balance cock table.
Train Counts and Beat Rate:
Great wheel 84 (fusee)
Centre wheel 80 pinion 12
Third wheel 75 pinion 10
Fourth wheel 72 pinion 10
Escape wheel 15 pinion 8
Beat rate: 16,200
Motion work: Intermediate 36
cannon wheel 36
minute wheel 36, minute pinion 6
hour wheel 72
Winding System: Chalfont and Key's keyless work. Three steel wheels are mounted on the fusee arbor. The lowest wheel is of ratchet form. Above this is a main winding wheel which meshes permanently with an intermediate winding wheel and also, when required, with the sliding intermediate hand-set wheel. Recessed into the main winding wheel is a further ratchet wheel. Also in the main winding wheel is a spring-loaded click which only engages in the recessed rathet wheel when the winding button is turned in the direction of wind. The main winding wheel meshes with an intermediate winding wheel which is turned by a bevel wheel mounted on the pendant stem. There are two levers held in engagement with each other by a spring to ensure that the watch is normally in the winding postion. When a push-piece in the case band is depressed it disengages the winding ratchet and causes the intermediate hand set wheel and pinion to engage with the winding wheel assembly allowing the hands to be turned in either direction by rotating the pendant button. The intermediate winding wheel is only in engagement with the intermediate hand-set wheel via the winding wheel assembly when the push-piece is depressed. The sliding hand-set wheel has an integral pinion which is permanently in mesh with the intermediate motion-work wheel and rotates feely as the watch runs. At the same time it should be noted that the watch retains key-operated winding and hand-setting squares on the back plate.(3)
Movement: diameter 44.0 mm, height 11.0 mm, pillar height 3.0 mm.
Provenance: formerly in the Ilbert Collection. Ilbert purchased this from Malcolm Gardner 31/12/1936.
(1) Mercer, The Frodshams, p.246 lists watch no.02184 with a date of 1863 and watch no 02408 dated 1865.
(2) See cat. no 147 (registration no. 1958,1201.915) note 1 for an explanation of Frodsham's AD Fmsz inscription.
(3) This pendant-operated winding and hand-setting mechanism was first patented by John William Chalfont, of 7 Denmark Grove, Islington and David Keys of 14 Craven Street, Strand, a watchmaker and a watchmaker/wholesaler, on 17 December 1861, patent number 3160. This patent was followed on 11 September 1865 with no. 2330 granted David Keys for a similar system. W.W. Chalfont of 6 Percy Street, Islington also communicated the following to the Horological Journal:-
Vol. XXII (Dec. 1879) pp.46-47, illustrated, 'Chalfont's ratchet-winding action for keyless fuzee watches'. This communication by W.W. Chalfont is based on the Chalfont and Keys' patent no. 3160
Vol. XXII (Feb. 1880) pp.76-77, illustrated, 'Chalfont's frictionless winding action for fuzee keyless watches'.
(4) For another watch with a variant of this system see Cat. no. 234 (registration no. 1958,1201.932).
Bibliography: Mercer, The Frodshams, pl. 85, p. 416.
- Not on display
Latest: 2 (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.1000 (Ilbert Collection)
Previous owner/ex-collection number: P127 (Ilbert Ledger)