- Museum number
MOVEMENT AND DIAL OF A LEVER CHRONOGRAPH WITH CENTRE-SECONDS.
3/4-plate; going barrel; club-tooth lever escapement; fly-back chronograph; keyless winding, rocking-bar hand-set.
White enamel dial; subsidiary seconds, minute circle calibrated for 1/5th seconds.
Hunter case missing
- Production date
Diameter: 39.30 millimetres (back-plate)
Diameter: 41.20 millimetres (dial)
Thickness: 12.10 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by American Waltham Watch Co.
Waltham USA, c. 1885
Chronograph watch movement with a club tooth lever escapement.
Signature: On the dial "A.W.W.C WALTHAM". On the back plate "A.W. Co. WALTHAM MASS 3038842. Pat. Sept 28. 80 Eng Pat 3224" and "Safety Pinion".
Dial and Hands: Dial with sunk subsidiary seconds and with a seconds ring around the outside divided into three hundreths of a second. In the counter-enamel in red 8. Blued-steel spade hands and blued-steel seconds hand.
Ebauche Marks: 38842
Frame: ¾ plate, all components numbered 3038842 including the barrel and its cover. The balance cock and the pallet bridge engraved.
Barrel, and Mainspring: Going barrel I. diameter 16.7 mm., height 2.3 mm.
Mainspring: height 2.1 mm., thickness 0.22 mm.
Arbor: diam. 5.5 mm., not snailed.
Hooking: T piece.
Train: Gilded brass wheels with five crossings except for the escape wheel which has four.
Jewelled: From the third onwards, all in screwed settings except for the three train holes in the front plate. The lever holes are not jewelled. The balance with ruby endstones. The back pivot of the centre seconds arbor also jewelled.
Escapement: Club tooth lever, straight line short lever, single roller, impulse pin D shaped. Exposed pallet stones, the impulse faces convex the locking faces flat. Brass escape wheel. Adjustable banking pins.
An equidistant locking escapement.
Number of teeth embraced 3 ½.
Balance: A split bimetallic balance, with brass screws, there are two timing screws opposite the ends of the arm. Balance diameter 15.5 mm., thickness 1.25 mm. Flat spiral blued-steel spring with 15 turns.
Means of Regulation: Index on the balance cock registering against a divided scale with engraved "F S".
Train Counts and Beat Rate:
Great wheel (barrel) 85
Centre wheel 80 pinion 12 Safety pinion threaded on to the arbor
Third wheel 75 pinion 10
Fourth wheel 80 pinion 10
Escape wheel 15 pinion 8
Beat Rate: 18,000
Motion work: cannon pinion 12, minute wheel 36
minute pinion 10, hour wheel 40
Chronograph Work: Operated by a side button acting on the ratchet teeth of an edge cam giving the three classic conditions; run, stop and zero. The chronograph train has no conventional teeth on its wheels but is furnished with fine angled edge serrations.
Winding System: Side lever set rocking bar keyless work.
Dimensions: Movement diameter 42.0 mm., height 12.3 mm
Provenance: Formerly in the Ilbert collection. Ilbert purchased this from Cox of Clerkenwell Rd 14/3/1932
(See L 1/4 for a similar example).
- 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.0904 (Ilbert Collection)
Previous owner/ex-collection number: L185 (Ilbert Ledger)