- Museum number
Square-dialled jewelled lever automatic wrist-watch with subsidiary seconds in a chrome-plated case with black leather strap.
15 jewel movement with lever escapement and Louis Müller's patent winding system; movement contained in spring-loaded carriage which slides back and forth to wind the watch.
Silvered metal dial with painted baton hour marks and subsidiary seconds.
Rectangular chromium-plated case with hinged bezel; outer case bezel raised to provide access for winding.
Crocodile-skin wrist-strap with gold-plated buckle.
- Production date
Length: 39.60 millimetres (case)
Length: 24.70 millimetres (dial)
Length: 232 millimetres (strap)
Thickness: 9.10 millimetres
Width: 25.10 millimetres (case)
Width: 19.20 millimetres (dial)
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Switzerland, 1931 or soon after.
Self winding wrist watch with club tooth lever escapement.
Signature: On the dial 'MARS AUTOMATIC'. On the back of the self winding block that locates the movement is '+PATENTS+ D.R.P. 529785'(1) USA PAT. APP. FOR PATENTS PENDING IN OTHER COUNTRIES'. On the movement is 'MARS AUTOMATIC 15 JEWELS ADJUSTED'.
Case: A three part case, chrome plated. The hinged bezel, which is unglazed, lifts to reveal the glazed inner cover which is snapped onto the band. The purpose of this outer cover is to hide the very large gap in the case which has to be there to allow the stem to move along as self winding occurs. This is because the whole self winding block which also carries the movement moves backwards and forwards in the case.
Dial & Hands: A silvered dial with black painted chapter ring and batons. A similar subsidiary seconds dial but with 5 seconds batons only, no seconds divisions. Blued-steel baton hands, blued-steel seconds hand.
Ebauche Marks 19 - 4
On the front plate under the dial is 'USA Pat. app. for. 1367790 DRP 459755 + 124382 + 134413 + 144348'.
Frame: A nickel silver frame of curious construction. The front plate is in two parts with the keyless block separate and integral with the part of the plate with the upper third jewel and the supporting parts for the bridges and cocks. A bridge for the barrel, one for part of the train and one for the escape wheel. Cocks for the fourth, the escape wheel and the balance. Under the balance cock is scratched 7.90.
Barrel and Mainspring:
On the going barrel is 'PATENT(2) + 131142. SWISS - MARS 19- 4'
Barrel I diameter 7.35 mm., height 1.15 mm. A recessed steel cover.
Mainspring: height 1.15 mm., thickness 0.08 mm.
Barrel Arbor: diameter 2.4 mm., snailed.
Hooking: A slipping mainspring.
Train: All the brass wheels are gilded, the centre wheel with six crossings, the third and fourth wheels with five crossings. The steel escape wheel with four crossings.
Jewelling: Jewelled bearings from the third wheel onwards, all the jewels friction set.(3) Ruby endstones to the cocks and the balance jewels set into gold chatons.
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 split bimetallic balance with brass screws. Balance diameter 7.65 mm., thickness 0.6 mm. The arm scratched underneath 790. A blued-steel flat spiral spring with 10 ½ turns.
Means of Regulation: An index on the balance cock registers against a divided scale with 'F S' and 'A R' engraved on the balance cock table.
Train Counts and Beat Rate:
Great wheel 55 (barrel)
Centre wheel 48 pinion 8
Third wheel 45 pinion 6
Fourth wheel 60 pinion 6
Escape wheel 15 pinion 6
A most unusual train.
Beat rate: 18,000
Motion work: cannon pinion 10
minute wheel 30, minute pinion 8
hour wheel 32
Self winding work: The round movement sits in a tonneau shaped block which contains two gears. The first is a ratchet wheel of 85 which carries a pinion of 8. The pinion drives a gear of 22 which meshes directly with the barrel ratchet wheel of 48 teeth. One to and fro motion of the block through the agency of a click indexes approx 2 ½ teeth of the ratchet wheel. Thus the ratio is approx 85/5 x 2/8 x 48 = approx 200:1.
Winding System: Conventional positive stem set keyless work.
Dimensions: Case length 36.0 mm., width 25.0 mm., height 9.0 mm., over the glass.
Movement diameter 19.0 mm., height 4.8 mm.
Provenance: Purchased in 1989 with the aid of funds from the Dingwall Bequest.
(1) The patent was taken out by Louis Muller & Co. in 1931.
(2) The intention here is no doubt to reduce the wear due to the constant slipping of the mainspring. This wear was to prove a constant source of trouble in self winding watches in general.
(3) If one ignores the crystal plated watch by Waltham then this may well be the earliest use of friction set jewels. See also watch registration no. 1989,0407.6, which has a date of c. 1940.
Literature: Ehrhardt and Demesey p. 394. Also Kahlert Muhe & Brunner p. 258.
- Not on display
- Latest: 4 (2017) lead weight burst
- Acquisition date
- Britain, Europe and Prehistory
- Registration number