- Museum number
NICKEL-SILVER CASED LEVER WATCH.
3/4-plate; going barrel.
Pin-pallet lever escapement; rocking bar keyless.
White enamel dial; hours I-XII; minutes 15-60.
Blued steel spade hands.
Nickel-silver case with glazed inner dome.
Diameter: 53.50 millimetres (case)
Diameter: 40.70 millimetres (dial)
Curvature: 18.50 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
ANONYMOUS but almost certainly made by the Jura Watch Company.
Switzerland, Date: c.1920
Watch with pin pallet lever escapement
Signature: None, but on the dial 'SYSTEME ROSKOPF PATENT' and '1a'
Case: Open face case with inside the back cover a glazed bezel. On the outside of the back within a circular cartouche is 'SYSTEME ROSKOPF' with a star set around a shield.
Dial and Hands: A flat enamel dial with hair line cracks and chipped where it is held by the screws at III and IX o'clock. Black Roman numerals and minute circle with the minutes numbered at 15, 30, 45 and 60. Blued-steel spade hands.
Ebauche Marks: None
Frame: Brass frame with the back plate supported by three pillars and secured by screws. The pallet cock is mounted on the back plate and the balance cock is screwed and steady pinned to another pillar. A bridge holds down the barrel ratchet wheel and its spring, the latter is now broken.
Barrel and Mainspring: The going barrel has a brass cover with the minute wheel mounted friction tight on this cover. Barrel inside diameter 22.0 mm
inside height 2.8 mm.
Mainspring height 2.75 mm., thickness 0.23 mm.
Arbor: Diameter 5.4 mm., snailed
Hooking: The barrel wall has four notches which restrain a turn of longer spring to which the mainspring is hooked. Therefore this is a slipping mainspring design.
Train: The brass wheels with five crossings, the steel escape wheel with four.
Jewelled: No jewels.
Escapement: A pin pallet escapement obtuse angle layout, long lever with effectively a double roller. A brass impulse finger. Steel escape wheel and lever, steel pallet pins.
An equal impulse escapement.
Number of teeth embraced 3 ½.
Balance and Spring: A brass three armed balance with a rounded rim. Balance diameter 15.9 mm., thickness 0.7 mm.
The flat spiral blued-steel spring with 11 turns.
Means of Regulation: An index on the balance cock which has stamped floral decoration and also with a divided scale and 'SF AR'.
Train Counts and Beat Rate:
Great wheel (barrel) 128. Rotates in 4 hours.
Centre wheel 84 pinion 8
Third wheel 60 pinion 7
Escape wheel 18 pinion 6
Beat Rate 17,280
Motion Work: Cannon pinion 18, minute wheel 72, minute pinion 22, hour wheel 66
Winding system: Side set positive keyless work
Dimensions: Case diameter 53.5 mm., thickness 18.1 mm., over the glass.
Movement diameter 43.6 mm., height 10.5 mm.
Provenance: Formerly in the Ilbert collection.
- Not on display
- Latest: 3 (2017)
- Acquisition date
- Britain, Europe and Prehistory
- Registration number
- Additional IDs
Previous owner/ex-collection number: CAI.1093 (Ilbert Collection)
Previous owner/ex-collection number: M20 (Ilbert Ledger)