- Museum number
MOVEMENT AND DIAL OF A LEVER WATCH WITH CENTRE-SECONDS AND STOP LEVER.
3/4-plate; going-barrel; rocking-bar keyless.
Lever escapement; resilient banking.
Stop lever acts on balance.
White enamel two-piece dial; centre-seconds.
Blued steel fleur-de-lys hands.
- Production date
Diameter: 39.30 millimetres (back-plate)
Diameter: 43.10 millimetres (dial)
Thickness: 9.70 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by William Edwards
Birmingham, c. 1875
Movement of a centre-seconds stop-watch with a resilient ratchet tooth lever escapement.
Signature: 'Wm Edwards 44. New St BIRMINGHAM. 53316 PATENT RESILIENT' on the back plate.
Case: Missing, the movement was held in the case by a locating pin and two dog screws.
Dial & Hands: A flat dial with a sunk centre. The seconds circle is marked with 1/5ths of a second and numbered at every five seconds. The number '3' is fired faintly into the counter-enamel. Blued-steel fleur de lys hour and minute hands and a blued-steel centre-seconds hand.
Dial-Pate: None intended.
Dust-Cap: None intended.
Ebauche Marks: 10.0 J.W.
Frame: A 3/4 plate layout, the back plate supported by four turned pillars and retained by screws. The balance cock is engraved on the outside with foliate scrolls and is stamped on the underside of the foot with a mark similar to a sea horse or perhaps a bird. The fourth wheel is at the centre of the movement.
Barrel and Mainspring:
Barrel: going barrel with Geneva stop-work but now only the finger survives. Barrel internal diameter 17.2 mm, height 2.0 mm. Mainspring: height 1.8 mm, thickness 0.20 mm.
Barrel Arbor: diameter 5.0 mm, not snailed
Train: Gilded wheels, the centre, third and fourth wheels with five crossings. The fourth wheel is planted at the centre of the watch and carries the centre-seconds hand.
Jewelling: Jewelled bearings from the third wheel onwards. All the jewels are in screwed settings except for the third and fourth jewels in the front plate which are rubbed-in. Ruby endstones for the escapement.
Escapement: An acute-angle layout ratchet tooth lever escapement with short lever, single roller and a D-shaped impulse pin. The banking consists of a C-shaped spring attached to a steel post with the free ends providing the resilient banking.(1) The enclosed pallet stones are convex on the impulse and locking faces.
An equal impulse escapement.
No. of teeth embraced 32.
Balance and Spring: A split bimetallic balance with gold compensation and timing screws. Balance diameter 16.5 mm, thickness 1.2 mm. A blued-steel flat spiral spring with 143 turns attached to a polished steel stud screwed to the balance cock table. The balance staff is broken.
Means of Regulation: An index on the balance cock registers against a divided scale with 'F' and 'S' engraved on the balance cock table.
Train Counts and Beat Rate:
Great wheel 75 (barrel)
Second 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: intermediate wheel 36
cannon wheel 36
minute wheel 36 minute pinion 6
hour wheel 72
An intermediate wheel, mounted on a friction-tight pin in the hollow second wheel arbor, drives the minute wheel and pinion. The hand-set square at the rear end of the pin is now missing. A brass spring in a brass block on the front plate bears on the minute wheel to eliminate backlash.
Stop Mechanism: A lever causes a wire detent to touch the balance rim.
Winding System: Conventional side-set, rocking bar keyless work.
Movement: diameter 43.0 mm, height 10.0 mm, pillar height 3.0 mm.
Provenance: Formerly in the Ilbert Collection. Ilbert purchased this from Malcolm Gardner in 1946.
(1) This escapement was the subject of patent no. 56 dated 10th January 1871 taken out by Mortimer George Cole. It reads as follows:-
'This invention relates to timekeepers in which a balance and a lever escapement is employed. The object of the invention is to obviate the evils resulting from the giving of an unusually great impulse to the balance. The ordinary banking pins are dispensed with and a spring takes their place. The spring is tempered and is bent round into position. By this arrangement the ruby pin can pass the horns of the lever when an extra motion is given to the balance'.
This patent outlining the use of a C-shaped spring follows an earlier patent, no.657 of 4 March 1869 where Cole uses a straight spring attached to the pallets and operating between two banking pins.
For more details of M. G. Cole and his relationship with E. Dent see Dr V. Mercer, Dent, 1977, pp. 465-468. Mercer comments that a number of watches having this escapement survive, mostly signed E Dent & Co., but quite a number are signed M. F. Dent and a few others are signed by various makers such as Hardy Bothers.
- 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.0990 (Ilbert Collection)
Previous owner/ex-collection number: Q123 (Ilbert Ledger)