- Museum number
MOVEMENT AND DIAL OF A LEVER WATCH WITH SPLIT CENTRE-SECONDS.
Bar movement; going barrel; club-tooth lever escapement; split bi-metallic balance; balance spring with overcoil.
Silvered engraved dial with sunk subsidiary for hours and minutes.
Split centre seconds.
Blued steel hands.
- Production date
Diameter: 47.70 millimetres (dial)
Thickness: 9.80 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by E. J. Dent
London and probably Switzerland, 1846
Movement with split seconds chronograph and club tooth lever escapement.
Signature: On the barrel cock 'E J Dent Compound Movement'. On the dial 'E J Dent Chronometer Maker to the Queen no. 10951'.
Dial and Hands: An engraved silvered brass dial retained by a single screw in the upper half. The subsidiary time of day dial is recessed in a hole in the main dial and held by two screws from behind. Scratched on the back of the dial 10951. Moon hands, the tip of one broken and missing, both of blued-steel with counterpoise extensions.
Ebauche Marks: none.
Frame: Lepine construction, built up on either side of recessed front plate. The movement was retained in its case by two dog screws and positioned by two pegs. The second wheel is offset with the fourth wheel at the centre.
Barrel and Mainspring: A going hanging barrel supported by a cock, the barrel ratchet mounted on the side of the cock in typical Swiss fashion. A steel barrel bridge beneath the dial furnished with a brass bush for supporting the upper barrel pivot. The barrel fitted with Geneva stopwork.
Barrel I. diameter 18.3 mm., height 2.4 mm.
Mainspring height 2.3 mm., thickness 0.23 mm.
Arbor: diameter 5.9 mm., not snailed.
Hooking: round. The mainspring with a T piece about a 1/6 of the way around the barrel wall from the hooking.
Train: Brass wheels, not gilded, centre, third and fourth wheels with five crossings, the steel escape wheel with four.
Jewelled: From the third onwards, the balance with ruby endstones, the jewels bombé and rubbed in.
Escapement: Club tooth lever, right angle layout, short lever, single roller, impulse pin elliptical. Pallet stones exposed the acting faces flat. One piece pallet frame and lever. Escape wheel of steel, polished all over, teeth chamfered both sides. Solid banking i.e. no banking pins, banking against the side of the plate recess.
An equidistant locking escapement.
Number of teeth embraced 3 ½.
Balance and Spring: A split bimetallic balance with gold compensation screws, a steel screw in each of the short rims at the ends of the arm and two small brass screws. Balance diameter 17.6 mm., thickness 1.2 mm. A blued-steel flat spiral spring with 11 turns and an inner and outer terminal curve. A Breguet stud clamped under a steel plate giving radial adjustment. The steel plate probably not original.
Means of Regulation: Index on the balance cock registering against a divided scale with engraved "F S".
Train Counts and Beat Rate:
Great wheel (Barrel) 96
Centre wheel 80 pinion 12
Third wheel 75 pinion 10
Fourth wheel 70 pinion 10
Escape wheel 15 pinion 7
Beat rate: 18,000
Motion work: cannon pinion 10, minute wheel 30, minute pinion 8, hour wheel 32.
Stop-catch up mechanism: For the upper sweep centre seconds hand. A push piece in the pendant is made to advance a star wheel with jumper by one tooth space at a time. On the underside of the star wheel is a series of indentations corresponding with every alternate tooth space. A steel arbor passing through a hole in the front plate is caused to move up and down as the star wheel rotates. This rocks a spring-loaded steel system pivoted like a see-saw about a shoulder screw on a block on the back of the front plate. The hollow fourth arbor has an extended pivot at both ends, on the front to carry the lower sweep centre seconds hand, and on the back sliced off at 45° to the axis. Down the hollow arbor passes a steel arbor with the other seconds hand on the front end and a mushroom-shaped piece on the end of short tube, also sliced at 45° on the other end. In one position of the star wheel the mushroom shaped end is held down with the two 45° faces in contact, thus the arbor and rod are held relative to each other and the two seconds hands coincide one above the other and move round together. In the other position of the star wheel, the mushroom-shaped piece is withdrawn, whereupon the upper seconds hand stops. A further advance of the star wheel causes the upper seconds hand to catch up the lower and move round with it again.
The mechanism is an early example of split-seconds work for timing short intervals.
Winding System: Keywound.
Dimensions: Movement diameter 47.3 mm., height 10.5 mm.
Provenance: Formerly in the Ilbert collection; purchased by Ilbert from Desoutter in 1935.
Watches numbers 10950 and 10952 are recorded in Dent's books as manufactured by Gibbons and appear in 1846. No. 10951 is not mentioned and so was possibly bought in as a complete watch from Switzerland and sold by the firm.
- Not on display
Latest: 2 (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.0981 (Ilbert Collection)
Previous owner/ex-collection number: N309 (Ilbert Ledger)