- Museum number
WATCH MOVEMENT WITH GOING-BARREL, KEYLESS-WORK, CENTRE-SECONDS, AND RATCHET-TOOTH LEVER-ESCAPEMENT.
3/4-plate, going-barrel, Geneva stop-work, Swiss rocking-bar keyless-work, centre-seconds by an idle 4th. pinion passing through a hollow centre-pinion and driven by a ancillary wheel mounted on the back 3rd-wheel pivot the backlash being taken up by a spring acting on the idle 4th. arbor [this whole arrangement is mounted on the back-plate under cocks], ratchet-tooth lever-escapement, gold escape-wheel, Earnshaw compensation balance, Breguet overcoil.
Dial; 2-piece, sunk centre, enamel, white with black I-XII numerals, minute/seconds circle marked in minutes/seconds and 1/5's 25-300.
Hands; blued steel spade hands and centre-seconds hand.
- Production date
Diameter: 30.10 millimetres (back-plate)
Diameter: 32 millimetres (dial)
Thickness: 18.20 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Hahn, Landeron.(1)
Landeron, Switzerland, c. 1910
Movement of a centre-seconds ratchet tooth lever watch.
Signature: 'HAHN LANDERON' on the inside of the back plate
Case: Missing, the movement was held in the case by a locating stud and two dog screws.
Dial and Hands: Flat dial with sunk centre. The minute circle surrounded by a seconds circle marked in fifth seconds and numbered 25-300 for 1/5th seconds. Blued-steel spade pattern hour and minute hands, blued-steel centre seconds hand.
Ebauche Marks: "DÉPOSÉ 68102" on the front plate and '102 HAHN LANDERON' on the inside of the back plate.
Frame: 3/4 plate layout, the back plate supported by three turned pillars and secured by screws. A combined pallet and escape wheel cock and a plain balance cock. A keyless block is screwed to the front plate to carry the stem and the winding pinion.
Barrel and Mainspring:
Barrel: going barrel with four-turn Geneva stopwork. Internal diameter 12.5 mm, height 1.50 mm.
Mainspring: height 1.43 mm. thickness 0.16 mm.
Barrel Arbor: diameter 4.3 mm, snailed.
Train: The wheels are gilded on one side only. The centre, third and fourth wheels have six crossings. The train is laid out for indirect centre seconds with an ancillary wheel mounted on an extension to the third wheel rear pivot which drives an idle centre seconds pinion with an anti-backlash spring acting on the central fourth pivot.
Jewelling: Jewelled bearings for the fourth wheel onwards in the front plate and for the third wheel onwards on the back plate including the centre seconds pinion. All the jewels are rubbed in. The front balance jewel is carried in a circular polished steel disc recessed into the front plate and retained by a screw.
Escapement: A right-angle layout ratchet tooth escapement with short lever, single roller and elliptical impulse pin. The pallet stones are enclosed, both impulse faces and the entrance locking face are convex but the exit locking face is flat. The gold escape wheel has three crossings.
An equal impulse escapement.
No. of teeth embraced 32.
Balance & Spring: A split bimetallic balance with brass compensation and quarter screws, balance diameter 12.5 mm, thickness 0.3mm. Blued-steel flat spiral spring with 14 3/4 turns with a terminal curve attached to a polished steel stud screwed to the balance cock.
Means of Regulation: An index on the balance cock registers against a divided scale with 'F' and 'S' engraved on the balance cock table.
Train Counts and Beat Rate:
Great wheel 80 (barrel)
Centre wheel 64 pinion 10
Third wheel 60 pinion 8 Ancillary third wheel 75
Fourth wheel 60 pinion 8 Idle centre seconds pinion 10 (with a drag spring)
Escape wheel 15, pinion 6
Beat rate: 18,000
Motion Work: cannon pinion 10
minute wheel 30, minute pinion 10
hour wheel 40
Winding System: Keyless winding with side-set rocking bar hand set mechanism. A squared stem carries the winding pinion.
Movement: diameter 32.0 mm, height 9.0 mm, pillar height 2.2 mm.
Provenance: Formerly in the Ilbert collection.
(1) Charles Hahn and Company were makers of ebauche in Landeron and made 500 different calibres between 5 and 40 lignes in size (11 mm-90 mm). In 1918 there were 130 employees and in 1927 the firm was affiliated to the Ebauche Group under the name of Landeron.
- Not on display
Latest: 3 (2017)
3 (Mar 1996)
- 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.1260 (Ilbert Collection)