Stainless-steel cased automatic winding centre-seconds club-tooth lever wrist-watch with day-date mechanism

Description — British Museum

Wrist-watch. Movement with automatic winding and club-tooth lever escapement. Black painted dial with outer adjustable seconds ring numbered every ten divisions in Arabic; inner ring for minutes and white luminous baton hour markers with wider baton at 12; rectangular aperture to right for day and date indications. Steel hour and minute hands with luminous bars; red-painted centre-seconds hand. Stainless-steel case with snap-on bezel and screw-on back; pull-out hand setting button at 4 o'clock.

Curator's comments — British Museum

Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript) Made by Seiko Watch Co. Japan, c. 1960 Self wound wrist watch with day date and a club tooth lever escapement. Signature: On the dial 'SEIKO JAPAN WATER 70 RESIST 21 JEWELS linked chevrons JAPAN 6119 60205'. On the self winding bridge 'SEIKO 21 JEWELS JAPAN 6119C'. Case: A two part stainless steel case with a screw back. On the outside of the back is 'SEIKO' with two chevrons, 'STAINLESS STEEL 6119-6023 WATER RESISTANT 331835 JAPAN F'. There is a rotatable insert in the case and this surrounds the glass and has black and white minute marks which are numbered 10, 20, 30, 40, and 50. Dial and Hands: A black dial with batons filled with luminous paint. An aperture for the day and date indication. The day dial is printed in both French and English. At the centre of the dial is "C Ring UPWARDS No 870 557 T" and an inscription in Japanese. The day and dates are in white on a black background but with Sunday in red. Printed on the back of the dial is 32. Rhodium plated baton hour and minute hands, skeletonised and filled with luminous paint. The red centre seconds hand has a moon end and this is also filled luminous. The day dial is retained by the C ring referred to on the dial. Movement: Ebauche Marks: none. Frame: A nickel silver movement. A bridge for the barrel and another for the train, a cock for the centre wheel a bridge for the pallets and a cock for the balance. Barrel and Mainspring: A recessed cover to the barrel. Barrel: I diameter 11.2 mm., height 1.0 mm. Mainspring: height 1.0 mm., thickness 0.09 mm. Barrel Arbor: diameter 2.8 mm., snailed. Hooking: A slipping mainspring with the outer turn of the spring reinforced by a single turn of thicker spring. Train wheels of brass, gilded. The centre, third, and escape wheels (this latter steel) with five crossings, the fourth wheel with six. Jewelled: from the centre onwards, the jewels pressed in, endstones to the escape wheel. Shock protected bearings to the balance of the KIF type but known in this watch as the "Diashock Shock Resistant Device". Escapement: A straight line layout club tooth escapement, short lever, double roller, the impulse pin D shaped. The pallet stones exposed with flat acting faces. The escape wheel of steel. Solid bankings on the pallet bridge. A mixed escapement. Number of teeth embraced 3 ½. Balance & Spring: a four arm monometallic balance with brass screws. Balance diameter 11.7 mm., thickness 0.4 mm. A 'self compensating' flat spiral spring with 13 ¾ turns. Means of Regulation: An index on the balance cock registers against a divided scale with + and - engraved on the balance cock table. Train Counts and Beat Rate: Great wheel 84 (barrel) Centre wheel 75 pinion 12 Third wheel 64 pinion 8 Fourth wheel 96 pinion 10 Escape wheel 15 pinion 8 An unusual train. Beat rate 21,600 Motion work: cannon pinion 12 minute wheel 36, minute pinion 8 hour wheel 32 Self Winding System: The weight runs on a ball race and is eccentrically mounted. It carries a ratcheting lever which has click terminations that, as the weight revolves, alternatively pull and push on the fine tooth ratchet wheel. This latter wheel carries a pinion which meshes directly with the barrel ratchet wheel. Day and Date work: the hour wheel of 32 drives a plastic pinion of 16 so that this revolves once in a ¼ of a day. This plastic pinion is integral with another of 12 leaves which in turn drives the calendar indexing wheel of 48, this revolving once a day. A plastic cam on the indexing wheel propels the date ring. Winding System: Conventional positive stem set keyless work but there is no winding pinion so no provision for manual winding, only hand setting. The stem carries another pinion for setting the adjustable minute ring. Dimensions: Case: Diameter 38.0 mm., height 13.2 mm. Movement: Diameter 26.7 mm., height 7.2 mm. Provenance: Purchased in 1986 with the aid of funds provided by Stanley H. Burton. Note 1: For an almost identical example see registration no. 1986,1024.2.