- Museum number
SILVER CASED LEVER WATCH WITH JUMP-HOURS AND MINUTES.
Keyless winding and hand-set.
Enamel dial; jump hours and minutes in apertures; subisidary dial for seconds.
Hours and minutes indicated by numbered discs appearing in dial apertures; blued-steel seconds hand.
- Production date
Diameter: 53.60 millimetres (case)
Diameter: 41.10 millimetres (dial)
Thickness: 17.70 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Switzerland, c. 1900
Silver cased watch with digital display and a club tooth lever escapement.
Signature: "Patent A KAISER" on the back plate and "Kaiser's Patent"(1) on the dial.
Case: Silver open face case with the Swiss quality mark and 800 in a cartouche. The outer dome marked S7, both domes and the pendant numbered 734.
Dial and Hands: As with registration nos. 1958,1201.1100 and ?1958,1201.901? (L6/23 and L½ ) but the enamel decorated with pellatons of gold and silver. However the under metal dial only provides a mask for the numerals, cocks are provided to support the pivots of the 'tens of minutes' and 'minute' discs. The seconds hand is of blued-steel.
Ebauche Marks: 734 2
Frame: The movement with a combined barrel and centre wheel bridge and a third and fourth wheel bridge, a combined escape wheel and pallet cock and a balance cock, the foot of this latter is engraved. All of these parts stamped 2.
Barrel and Mainspring: Recessed cover the going barrel I. diameter 17.4 mm., height 3.15 mm.
Mainspring: height 3.2 mm., thickness 0.23 mm.
Arbor: diameter 5.8 mm., not snailed.
Train: The brass wheels gilded one side only. Five crossings except for the steel escape wheel which has four.
Jewelled: From the third onwards in the back plate, from the escape wheel onwards in the front plate. Jewels rubbed in, ruby endstones for the balance. The jewel in the cock for the fourth wheel has been replaced by a soldered-in bush.
Escapement: Club tooth lever, straight line layout, short lever, single roller, impulse pin elliptical. The pallet stones are convex on the acting faces. Escape wheel steel, polished both sides, the tooth tips chamfered. The pallet staff is screwed in and has a poising tail.
A mixed escapement.
Number of teeth embraced 3½.
Balance: An uncut bimetallic balance , diameter 17.0 mm., thickness 0.9 mm. A blued-steel, flat spiral spring with 12 turns.
Means of Regulation: An index on the balance cock registering against a divided scale with engraved 'A R'.
Train Counts and Beat Rate:
Great wheel (barrel) 80
Centre wheel 80 pinion 12
Third wheel 64 pinion 10
Fourth wheel 70 pinion 8
Escape wheel 15 pinion 7
Beat Rate: 18,000
Digital Display Work: Yet another variant with a similar third wheel assembly to cat no. 0-0 (that with the ancillary spring) but unlocking in a different way. The continuously rotating third wheel and the intermittently disc indexing wheel each carries a cam with ratched toothed projections. The cam on the small barrel assembly is locked by a detent which is lifted each minute as one of the ratchet teeth of the cam on the third wheel passes. The barrel arbor of the barrel assembly carries an 8 toothed pinion which meshes with the minute disc through an idle pinion. The minute disc carries a finger which at each revolution indexes the 'tens of minutes' disc through another intermediate disc with 10 vertical projection, i.e. a disc that revolves once every 100 minutes. This disc also has 50 gear teeth on its periphery and it is this gear that meshes with a gear of 30 on the 'tens of minute' disc. 50 to 30 is of course the same ratio as 100 to 60 this giving the correct rate of revolution to the 'tens of minutes' disc which revolves every 60 minutes. A finger on the 'tens of minute' disc indexes the hour wheel, which has 12 upstanding teeth, each hour.
Winding System: Side set positive keyless work. On pressing the hand-set button (which, unusually, is nearly at right angles to the pendant) the intermediate pinion between the third wheel and the minute indicating wheel is thrown out of mesh. At the same time the sliding pinion is brought into action and the discs can be set.
Dimensions: Case diameter 53.6 mm., height 17.6 mm., over the glass.
Movement diameter 43.2 mm., height 10.7 mm.
Provenance: Formerly in the Ilbert collection. Ilbert purchased this from Gould in August 1947.
(1) There is a patent by A. Kaiser but it is not relevant to this watch as it covers an escapement.
- 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.1133 (Ilbert Collection)
Previous owner/ex-collection number: Q137 (Ilbert Ledger)