Ladies stainless steel cased automatic centre-seconds wrist-watch with expanding stainless steel bracelet

Description — British Museum

Movement with automatic winding and club-tooth lever escapement. White-painted metal dial with raised baton hour markers and minute circle. Stainless-steel hands; centre-seconds hand plain; hour and minutes hands with black stripe. Stainless-steel case with screw-on back. Stainless-steel expanding bracelet.

Curator's comments — British Museum

Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript) Made by Omega Watch Company Switzerland, c. 1970 Ladies self winding wrist watch with a club tooth lever escapement. Signature: On the dial the Omega trade mark and 'OMEGA Ladymatic SWISS MADE'. Case: A stainless steel two part case with a screw back. The button with the Omega trade mark. The outside of the case back stamped with a representation of a seahorse. The inside of the back stamped with 'OMEGA WATCH Co' in a triangular cartouche 'FAB SUISSE SWISS MADE STAINLESS STEEL S.F' and the numbers 11000.61 followed by 'SC' An expanding metal strap with each link marked 'FIXO-FLEX-S' and the end terminations marked respectively 'MADE IN GERMANY' and 'ROM STAINLESS STEEL PAT 1149932'. Dial & Hands: A silvered metal dial with rhodium plated applied batons for the hour marks with a wider one for the 12 o'clock. The back of the dial is stamped with the number 32130 and ZO. The hour and minute hands and the centre seconds hand also finished by plating with rhodium, the centre seconds hand is without a tail. Movement: Finished in a pink colour. The self winding weight marked 'OMEGA WATCH Co SWISS'. Ebauche Marks: on the inside of the front plate is the number 18251538. On the self winding work bridge is the Omega letter with within it a 2 and below it 455, also 'SEVENTEEN 17 JEWELS'. Frame: The self winding work can be removed complete by releasing two screws. The last pinion in the gear train meshes with the barrel ratchet wheel which is thickened so that part of it is in the correct plane. A bridge for the barrel and keyless work and for part of the train, another for the fourth and escape wheels and cocks for the pallets and balance. Barrel and Mainspring: the going barrel with a recessed cover. Barrel: I diameter 6.4 mm., height 1.18 mm. Mainspring: height 1.18 mm., thickness 0.075 mm. Barrel Arbor: diameter 2.15 mm., snailed. Hooking: A slipping mainspring. Train: All the wheels gilded, the centre, third and fourth wheels with five crossings. The steel escape wheel with four. Jewelling: Jewelled bearings from the third wheel onwards, all the jewels pressed in. Shock protected jewelling to the balance pivots. Escapement: A straight line layout, club tooth lever escapement with short lever, double roller and D-shaped impulse pin. The exposed pallet stones have flat acting faces. A steel escape wheel with four crossings. An equal impulse escapement. No. of teeth embraced 3½. Balance & Spring: a monometallic balance with brass screws. Balance diameter 6.45 mm, thickness 0.55 mm. A 'self compensating' flat spiral spring with 10 turns. Means of Regulation: An index on the balance cock registers against a divided scale with 'A' and 'R' engraved on the balance cock table. Train Counts and Beat Rate: Great wheel 70 (barrel) Centre wheel 64 pinion 10 Third wheel 60 pinion 8 A wheel of 60 mounted on an extended pivot of the third pinion driving the centre seconds pinion of 8. This pinion is held down by a drag spring. Fourth wheel 66 pinion 8 Escape wheel 15 pinion 6 Beat rate 19,800 Motion work: cannon pinion 10 minute wheel 40, minute pinion 12 hour wheel 36 Winding System: Conventional positive stem set keyless work, the bolt spring broken. Self winding work: The figure explains the principle of the self winding work. Dimensions: Case: Diameter 19.5 mm., height over the glass 10 mm. Movement: diameter 16.3 mm., height 7.8 mm. Provenance: Purchased in 1989 with the aid of funds from the Dingwall Bequest.