- Museum number
Lever escapement; two going barrels.
- Production date
Diameter: 31.10 millimetres (back-plate)
Diameter: 33.20 millimetres (dial)
Thickness: 7.30 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
England, c. 1870
Movement of a ratchet tooth lever watch with twin going barrels and an impulse roller with two impulse pins.
Signature: inscribed on the back plate 'PATENT No.13078'
Case: Missing, the movement was held in the case by a locating peg and two dog screws.
Dial & Hands: Flat dial with a sunk subsidiary seconds dial. Fired into the counter-enamel, in red, the number '8'. There is damage to the enamel at XI and fine cracks radiate from the centre hole. Blued-steel moon pattern hour and minute hands and a blued-steel seconds hand with a large diameter boss. None of these hands is original.
Dial-plate: None intended.
Dust-cap: None intended.
Ebauche Marks: 8
Frame: An unusual layout of the 3/4 plate type with a solid back plate extended to surround the balance and balance cock. There are also two circular cut outs for the standing barrels. The combined pallet and escape wheel cock is not gilded. The front plate, a large un-gilded plate retained by five screws, covers the winding work and carries the jewelled bearings for the third and fourth wheels and the escapement.
Barrels and Mainsprings:
Barrels: identical twin going barrels both fitted with five-turn Geneva stop-work.
Internal diameter 12.0 mm, height 1.0 mm.
Mainsprings: two identical mainsprings, height 0.97 mm, thickness 0.15 mm.
Barrel Arbors: both arbors, diameter 3.5 mm, not snailed.
Each barrel has a square section hole through its arbor and the squared winding wheel arbor passes through this. The arbor has the Geneva finger mounted on it and is retained by a pin which holds the entire assembly together. One of the barrels is not gilded on the outer surface.
Train: Twin great wheels drive a common centre pinion. All the wheels gilded, the centre wheel solid, the third and fourth wheels with five crossings.
Jewelling: Jewelled bearings from the centre wheel onwards except for the pallets. All the jewels, apart from the centre wheel bearing in the back plate, are in screwed settings. The escape wheel and balance have ruby endstones.
Escapement: An acute-angle layout ratchet tooth lever escapement with a very short lever, only 5.4 mm in length and a single roller with two brass impulse pins. The pallet stones enclosed, the impulse faces and the entrance locking face are convex, the exit locking face is flat.
A mixed impulse escapement.
No. of teeth embraced 32
Balance & Spring: A rounded-rim, three-arm gold balance, diameter 11.3 mm, thickness 0.50 mm. A blued-steel flat spiral spring with 7 turns pinned to a polished steel stud on the back plate.
Means of Regulation: An index on the balance cock registers against a divided scale with 'FAST' and 'SLOW' engraved on the balance cock table.
Train Counts and Beat Rate:
Great wheels: 60 (barrels)
Centre wheel 72 pinion 8
Third wheel 64 pinion 8
Fourth wheel 60 pinion 8
Escape wheel 15 pinion 7
Beat rate: 15,428.571.
Motion work: cannon pinion 10
minute wheel 30 minute pinion 8
hour wheel 32
Winding System: Key wound, a common winding wheel with with an arbor squared at the back for the key has ratchet teeth which engage with two ratchet wheels each mounted on one of the barrel arbors.
Movement: diameter 33.5 mm, height 7.0 mm, frame height 3.7 mm.
Provenance: Formerly in the Ilbert Collection. Ilbert purchased this from Wartski in 1946?
- Not on display
Latest: 3 (2017)
2 (Feb 1995)
- 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.1233 (Ilbert Collection)
Previous owner/ex-collection number: Q124 (Ilbert Ledger)