- Museum number
POCKET-CHRONOMETER MOVEMENT WITH PIVOTED DETENT ESCAPEMENT.
Pivoted detent escapement.
- Production date
Diameter: 41.60 millimetres (back-plate)
Diameter: 44.60 millimetres (dial)
Thickness: 11.20 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by M. B. Lee and Son, c. 1900
Signature: On the back plate 'M. B. Lee and Son 155 Oxford Street MANCHESTER NO. 3334'. On the dial 'CHRONOMETER' 3334'.
Dial and hands: Flat enamel dial, retained to the front plate by three feet and pins.
Blued steel hands, the hour hand broken.
Movement: Ebauche marks 16 2
Front plate diam. 45.0 mm; back plate diam. 41.7 mm; frame h. 7.0 mm.
Frame: Typical half plate construction, with three turned pillars, the back plate retained by three recessed blued steel screws. The movement held in its case by a small hinge and a pin opposite passing into a hole in the middle of the case instead of a catch. The brass parts gilded.
Fusee: Keywind fusee with the usual stop-work and maintaining power, the maintaining ratchet wheel steel. The setting-up-work under the dial on the front plate, the barrel arbor with an extended square on that end only.
Going train: The centre arbor hollow for the hand-set arbor carrying the cannon pinion. The train well finished, the brass wheels gilded.
Jewelling: Only the pivots of the escape arbor and balance staff in pierced jewels, with endstones, the diamond endstone in the balance cock missing.
Escapement: A development of the Earnshaw detent escapement. The brass escape wheel with rim and arms sunk below the level of the teeth. The jewelled discharge roller without an adjusting flat sandwiched between the radially jewelled impulse roller and the back slope of the balance staff. The detent with its passing spring missing and the locking stone replaced by a piece of brass wire. Banking for the detent provided by a brass piece screwed in a recess on the end of the escape cock.
Balance: Bimetallic two-armed balance with gold compensation and quarter screws. The steel parts do not appear to have been blued. Diam. 18.5 mm, h. 1.4 mm.
Balance spring: Free sprung, blued steel, open coil, spiral spring of 10¾ open turns and with an overcoil and theoretically incorrect terminal curve. A brass collet on the balance staff and a diamond-shaped stud on the balance cock.
Great wheel (fusee) 72 teeth
Centre pinion 12 leaves, wheel 80 teeth, 5 arms
Third pinion 10 leaves, wheel 75 teeth, 5 arms
Fourth pinion 10 leaves, wheel 80 teeth, 5 arms
Escape pinion 8 leaves, wheel 15 teeth, 5 arms
Beats per hour: 18,000
Cannon pinion 12 leaves, minute pinion 10 leaves
Hour wheel 40 teeth, minute wheel 36 teeth
Provenance: Ilbert Collection; purchased by Ilbert in 1931.
- Not on display
Latest: 3 (2017)
3 (Oct 1995) Hour-hand broken off at boss. Pivoted detent missing.
- 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.1606 (Ilbert Collection)
Previous owner/ex-collection number: K75 (Ilbert Ledger)