- Museum number
SUBSIDIARY SECONDS CLUB-TOOTH LEVER MOVEMENT CONVERTED TO A DESIGN INCORPORATING BOTH SPRING AND PIVOTED DETENTS.
Spring-pivoted detent escapement; experimental, added later.
- Production date
Diameter: 38.20 millimetres
Thickness: 13.80 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Maker Unknown, c. 1900
Signature: On the barrel bridge 'J.W. Jennings BIRMINGHAM 14756'.(1)
Dial and hands: None.
Ebauche marks 12, 4. and on the underside of the balance cock w.c.
Front plate diam. 38.3 mm; back plate diam. 36.0 mm; frame h. 7.6 mm.
Frame: Typical English full plate construction. The brass parts electro-gilded.
Fusee: The usual construction, steel maintaining ratchet wheel.
Going train: The usual construction, the brass wheels burnished but not gilded.
Jewelling: Only the balance staff pivots in pierced jewels with endstones.
Escapement: Originally an English ratchet tooth lever escapement, later replaced by a form of detent escapement. The balance staff carries a table roller without a notch, and a steel pallet as in a duplex escapement. Impulse is given to the steel pallet by a ratchet-tooth lever escape wheel. Locking of the escape teeth occurs on a steel locking piece carried on the end of a spring detent. This detent is carried on a brass mounting with adjustments for depth of locking and spring tension. A pivoted detent performs the functions of unlocking the spring detent, and of passing action, when displaced by a jewel pin on the table roller. The pivoted detent carries another jewel pin to unlock the spring detent, and has a fine leaf spring to return it to rest against the stronger spring detent. It also has a forked tail so that it can be moved aside to remove or replace the balance.
Balance and spring: Plain steel three-armed balance, undersprung with a blued steel flat spiral spring of 10 full turns. Originally there was an index, now only the scale remains on the back plate. No compensation. Balance diam. 18.0 mm, h. 0.8 mm.
Great wheel (fusee) 70 teeth
Centre pinion 10 leaves, wheel 64 teeth, no crossings
Third pinion 8 leaves, wheel 60 teeth, 5 arms
Fourth pinion 8 leaves, wheel 56 teeth, 5 arms
Escape pinion 7 leaves, wheel 15 teeth, 3 arms
Beats per hour: 14,400
Motion work: Missing.
Provenance: Ilbert Collection; purchased by Ilbert in 1937.
(1) This is an experimental piece by an unknown maker.
- Not on display
Latest: 4 (2017)
4 (Oct 1995) Motion work missing. Balance spring stud pin missing. Spare holes relate to conversion.
- 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.1831 (Ilbert Collection)
Previous owner/ex-collection number: P202 (Ilbert Ledger)