- Museum number
MOVEMENT AND DIAL OF A HALF-HUNTER LEVER WATCH.
Savage-type lever escapement; split bi-metallic balance.
White enamel dial; hours I-XII; sunk subsidiary seconds.
Blued steel double-swell spade hands.
Half-hunter case missing.
- Production date
Diameter: 35.60 millimetres (back-plate)
Diameter: 39 millimetres (dial)
Thickness: 7.80 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by W. H. and S.Jackson.(1)
London, c. 1875
Movement of a ratchet tooth lever watch with two pins on the lever.
Signature: 'W H. & S. JACKSON LONDON' on the dial. 'W H & S. Jackson Invt London 27618 Clerkenwell' on the back plate.
Case: Missing, originally a half-hunter case with the movement hinged at XII.
Dial & Hands: A flat dial with Gothic hour numerals and a subsidiary seconds dial with a sunk centre. Blued-steel spade pattern hands the hour hand with a double swell for a half hunter display. A blued-steel seconds hand.
Dial-plate: None intended.
Dust-cap: None intended.
Ebauche Marks: 10 IG 27618, also a letter 'J' on the hinge.
Frame: 3/4 plate layout, the back plate supported by three turned pillars and secured by screws. A bridge on the front plate for the front bearing of the barrel arbor and a bridge carrying the ratchet and spring for the barrel ratchet wheel. A combined cock for the escape wheel and pallets. The balance cock is finely engraved with foliate scrolls. The combined escape wheel and pallets cock and the balance cock are both stamped '18' on the underside.
Barrel and Mainspring:
Barrel: going barrel with four-turn Geneva stopwork. Internal diameter 14.4 mm, height 2.0 mm.
Mainspring: height 1.60 mm, thickness 0.20 mm.
Barrel Arbor: diameter 4.6 mm, not snailed.
Train: A high quality gilded train, the centre, third and fourth wheels with five crossings.
Jewelling: Jewelled bearings from the fourth wheel onwards in the front plate and additionally for the third wheel in the back plate. All the jewels in screwed settings except for the front fourth wheel and rear third wheel jewels which are rubbed in. The escapement has ruby endstones in the front plate but there are no endstones in the cock for the escape wheel and pallets. A diamond endstone in the balance cock.
Escapement: A right angle layout ratchet tooth lever escapement. The lever has no notch, there being instead two gold pins working with a round impulse pin mounted radially in the roller. There is no dart, instead the end of lever has a chamfered end which works with a normal passing hollow. The enclosed pallet stones have convex acting faces except for the exit stone locking face which is flat. The gilded escape wheel has three crossings and the tips of the teeth are badly worn.
An equal impulse escapement.
No of teeth embraced 32.
Balance and Spring: A split bimetallic balance with gold compensation and quarter screws; balance diameter 13.3 mms, height 1.1 mm. Blued-steel flat spiral spring with 11 turns and a terminal curve 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 'S' and 'F' engraved on the balance cock table.
Train Counts and Beat Rate:
Great wheel 75 (barrel)
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
minute wheel 36, minute pinion 10 hour wheel 40
The cannon pinion is integral with a pin which passes through the hollow centre pinion and is secured by a loose hand set square which is pinned on. This loose square is missing.
Winding System: Key wound and key set, the winding arbor has a square hole and the missing hand set square had a square hole for a male key.
Movement: diameter 39.0 mm, height 8.5 mm, pillar height 2.1 mm.
Provenance: Formerly in the Ilbert Collection. Purchased by Ilbert from Collet 26/3/1938.
(1) Samuel Jackson was partner to W. H. Jackson c. 1842-1875. He died in 1904 aged 81. The firm was at 66, Red Lion St., Clerkenwell, London. Samuel was for many years Treasurer and Vice President of the British Horological Institute.
- 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.1023 (Ilbert Collection)
Previous owner/ex-collection number: P251 (Ilbert Ledger)