- Museum number
MOVEMENT AND DIAL OF A HALF-HUNTER LEVER WATCH.
3/4-plate; going barrel.
Savage type lever escapement;
Nielsen's (Dent's?) keyless work.
White enamel dial with subsidiary seconds at IX.
Blued steel double spade hands; seconds hand missing.
Half-hunter case missing.
- Production date
Diameter: 37.70 millimetres (back-plate)
Diameter: 39.10 millimetres (dial)
Thickness: 7.70 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Edward John Dent
London, c. 1850
Movement of a ratchet tooth lever watch with two pins on the roller.
Signature: 'E.J. DENT LONDON 22208' on the dial, and 'E.J. Dent Watchmaker to the Queen London No 22208 Patent' on the back plate.
Case: Now missing but originally was a half-hunter.
Dial & Hands: Flat dial with a subsidiary seconds dial with a sunk centre positioned near XI o'clock. The dial is secured by dog screws. Blued-steel spade pattern hour and minute hands, the hour hand with a double swell for use with a half hunter case. The seconds hand is missing.
Dial-plate: None intended.
Dust-cap: None intended.
Ebauche Marks: 2546 2220 (the 8 probably machined off when the plate was recessed).
Frame: A 3/4 plate layout without pillars, the front plate recessed to accommodate the wheels. The back plate is secured by three screws. A round disk set into the front plate carries the escapement jewels. The balance cock is engraved with foliate scrolls.
Barrel and Mainspring:
Barrel: going barrel with Geneva stop-work, the wheel now missing and the finger on the arbor broken off; internal diameter 14.3mm, height 2.2 mm. The barrel has a recessed cover.
Mainspring: height 2.1 mm, thickness 0.18 mm.
Barrel Arbor: diameter 5.0 mm, not snailed.
Train: All the wheels gilded, the centre, third and fourth wheels all with five crossings. The centre pinion is unpolished and still in the rough.
Jewelling: Jewelled bearings from the fourth wheel onwards in the front plate and the third wheel and escapement in the back plate. The escapement with ruby endstones, those in the combined pallet and escape wheel cock in steel endplates. The balance jewels in screwed settings, the rest are rubbed in.
Escapement: An acute-angle layout ratchet tooth lever escapement with a short lever, single roller and two gold impulse pins. The enclosed pallet stones have convex impulse and locking faces. The polished brass escape wheel has three crossings.
An equal impulse escapement.
No of teeth embraced 32.
Balance & Spring: A split bimetallic balance with gold compensation screws and platinum quarter screws. Balance diameter 15.7 mm, thickness 0.95 mm. Blued-steel flat spiral spring with 10 turns attached to a polished steel stud on the balance cock table.
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 80 (barrel)
Centre wheel 80 pinion 10
Third wheel 75 pinion 10
Fourth wheel 70 pinion 10
Escape wheel 15 pinion 7
Beat rate: 18,000
Motion Work: cannon pinion 12
minute wheel 36, minute pinion 10
hour wheel 40
Winding System: The revised version of Adolphe Nicole's keyless work.(1) The steel piece that holds the bevel winding wheel is missing. This bevel winding wheel drives a wheel which is in constant mesh with it and which winds the mainspring. This wheel can freewheel when moved in the opposite to the winding direction so that even when the watch is fully wound so that the hands can be set in the forward direction. They cannot however be set in the anti clockwise direction when the watch is fully wound. To hand set a side button is pressed and this moves an intermediate wheel that is in constant mesh with the winding wheel into mesh with the pinion on the minute hand arbor.
Movement: diameter 37.7 mm, height 7.8 mm, frame height 4.4 mm.
Provenance: Formerly in the Ilbert Collection.
(1) This revised keyless work is an improvement on Adolphe Nicole's original design, see cat no. 242 (registration no. 1958,1201.982). Here the pinion on the minute wheel arbor is in permanent contact with another wheel with a consequent waste of energy.
E. J. Dent had acquired the rights to use the Nicole winding work in about 1846, Nicole had patented this mechanism in 1844 (patent no. 10348). A pamphlet dated 1879 states that Dent was the sole licensee of its manufacture which explains why many of the watches having Nicole's keyless work are signed Dent. The system was in use until about 1862, See Mercer, Dent, pp. 275-279.
This movement is a similar calibre to cat. no. 242 although larger.
- 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.0983 (Ilbert Collection)
Previous owner/ex-collection number: N14 (Ilbert Ledger)