stop-watch
- Museum number
- OA.443
- Description
-
MOVEMENT AND DIAL OF A LEVER WATCH WITH STOP MECHANISM.
.
Full-plate; fusee; Harrison's maintaining power.
Lever escapement, converted from rack; stop acts on lever.
White enamel dial; sunk subsidiary seconds.
Gold hour hand; minute hand not original; blued steel seconds hand, broken.
Dust-cap missing.
Case missing.
- Production date
- 1825-1835
- Dimensions
-
Diameter: 39.40 millimetres (back-plate)
-
Diameter: 46.60 millimetres (dial)
-
Thickness: 17.50 millimetres
- $Inscriptions
-
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by James Miller
Glasgow, c. 1830
Movement of a rack-lever stop watch now converted to a ratchet tooth lever escapement.
Signature: On the barrel bridge 'Jas Miller PORT GLASGOW 400'.
Case: Missing.
Dial and Hands: A flat dial with heavy Roman numerals and a subsidiary seconds dial. Gold spade hour hand with the spade end dished. The minute hand is not original. The blued-steel seconds hand is broken and partly missing.
Dial-Plate: Gilt-brass dial plate without marks.
Dust-Cap: There is provision for a cap which is now missing
Movement:
Ebauche Marks: None
Frame: A full plate movement, the back plate supported by four turned pillars. A typical Liverpool style balance cock engraved with foliate scrolls and rosettes and with the number '1895' scratched on the underside of the foot.
Fusee, Barrel and Mainspring:
Fusee: six-turn fusee with Harrison's maintaining power, the maintaining ratchet wheel of brass.
Barrel: internal diameter 16.3 mm, height 4.90 mm.
Mainspring: height 4.65 mm, thickness 0.225 mm.
Barrel Arbor: diameter 5.1 mm, not snailed.
Hooking: Square.
Train: All the wheels gilded, the centre wheel solid, the third and fourth wheels with five crossings.
Jewelling: Only the balance pivots are jewelled with a diamond endstone in the balance cock and ruby endstone in a wedge in the potence.
Escapement: Originally a rack lever escapement now converted to ratchet tooth lever. The two-way slides for the original pallets are still present although not now used. The pallets are not the original. One pallet staff pivot is broken. Brass escape wheel with three crossings.
No. of teeth embraced 32.
Balance and spring: A rounded-rim, polished steel three-arm balance, diameter 20.1 mm, thickness 0.5 mm. A flat spiral blued-steel spring of 72 turns.
Means of regulation: A Bosley regulator registering against a divided scale with 'Fast' and 'Slow' engraved on the back plate.
Train Counts and Beat Rate
Great wheel 62 (fusee)
Centre wheel 64 pinion 12
Third wheel 60 pinion 8
Fourth wheel 56 pinion 8
Escape wheel 15 pinion 7
Beat rate 14,400
Motion work: cannon pinion 12, minute wheel 48
minute pinion 14, hour wheel 42
Stop mechanism: a lever between the dial plate and the movement causes a brass wire detent to act on the pallet frame.
Winding Mechanism: Key wound
Dimensions:
Movement: diameter 44.5 mm, height 18.0 mm, pillar height 4.9 mm.
Provenance: not known.
- Location
- Not on display
- Condition
- Latest: 3 (2017)
- Department
- Britain, Europe and Prehistory
- Registration number
- OA.443