- Museum number
MOVEMENT EBAUCHE FOR A LEVER WATCH WITH SPLIT-SECONDS CHRONOGRAPH, MINUTE-REPEAT, PERPETUAL-CALENDAR AND MOON-PHASE.
3/4-plate, going-barrel, English rocking-bar keyless-work; repeating, perpetual calendar, centre-seconds chronograph movement in unfinished state.
No dial apart from gold and blue enamel moon wheel.
- Production date
Diameter: 49.50 millimetres
Thickness: 28.30 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Switzerland, ca. 1900
Ebauche for a split-seconds chronograph with perpetual calendar, lunar indications, and minute repeat, intended for a lever escapement.
Case: Not yet fitted.
Dial and hands: Not yet fitted.
Ebauche marks: 11235
Frame: 3/4 plate layout, the back plate supported by four turned pillars and secured by screws (one missing). The repeating barrel arbor is pivoted in the back plate but the rest of the repeating train is under its own bridge. The second wheel is offset from the centre of the movement. The movement edge is scratched 11135. A separate sub-plate carries the perpetual calendar and lunar work.
Barrel and Mainspring:
Barrel: a going barrel with four-turn Geneva stop work. Internal diameter 13.6 mm, height 2.7 mm.
Mainspring: height 2.5 mm, thickness 0.20 mm.
Barrel Arbor: diameter 6.0 mm, snailed.
Train: Plain brass wheels not gilded and each with six crossings. The second wheel also carries another wheel which drives the minute recorder wheel. The fourth wheel carries a serrated pinion which meshes with the seconds wheel.
Jewelling: Jewelled bearings from the third wheel onwards, those jewels visible from the back are in screwed settings, also the two chronograph wheel pivot jewels in the shaped cock are in screwed settings. The back pivot of the repeating barrel is also jewelled. The escapement is not yet jewelled.
Escapement: Not yet fitted.
Balance and Spring: Not yet fitted
Means of Regulation: Not yet fitted.
Train Counts and Beat Rate:
Great wheel 86 (barrel)
Second wheel 80 pinion 10
Third wheel 75 pinion 10
Fourth wheel 80 pinion 20
Beat Rate: probably intended to be 18,000
Motion Work: cannon wheel 32
minute wheel 32, minute pinion 7
hour wheel 84.
The calendar driving wheel 30.
Chronograph Mechanism: A split seconds chronograph, with rocking wheels to engage and disengage the trains to the centre seconds and minute recording indications. The chronograph work was to be operated by a plunger roughly at right angles to the winding stem. This plunger was to operate a conventional castle wheel. The split seconds work is unusual in being separated, one of the centre seconds wheels being under the dial and the other on the back plate. For minute recording there is a wheel of 70 teeth mounted on the second wheel arbor, which in turn drives the minute recorder wheel which also has 70 teeth.
Repeating Work: The minute repeating work is of the most sophisticated type. The winding rack, although not of the divided variety, is held down by a chamfered guide and retaining piece. It was to be operated by a slide in the case band. There is of course an all-or-nothing device and the surprise piece operating lever is only engaged when the watch is being repeated. The speed of striking is controlled by a depthed pinion. The round section gongs are fitted. The train consists of five plain brass solid wheels and a weighted fly pinion.
Repeat Barrel and Mainspring:
Barrel: internal diameter 9.2 mm, height 1.9 mm.
Mainspring: height 1.9 mm, thickness 0.13 mm.
Barell Arbor: diameter 3.2 mm, not snailed.
Repeat train count:
Great wheel 50 (barrel)
Second wheel 40 pinion 6
Third wheel 36 pinion 6
Fourth wheel 32 pinion 6
Fifth wheel 30 pinion 6
Fly pinion 6
Calendar Work: The perpetual calendar work is mounted on a sub-plate and is driven by a wheel of 30 mounted on the hour wheel pipe. This drives an indexing wheel of 60 which therefore rotates once per day. A pin on the indexing wheel advances the calendar via a lever which indexes the calendar work. The perpetual calendar is of the continuous 48 month variety. There is a four-year wheel mounted with a cam cut with different depth steps for the months of 31, 30, 28 and 29 days. This cam through a lever affects the indexing of the date wheel at the end of each month. There is no effect at the end of a 31 day month, one day extra is indexed at the end of 30 day month, three days at the end of the normal February and two days at the end of the leap year February (once every four years).
Perpetual lever indexing wheel, 60 i.e. once a day.
Month wheel with cam for operation by perpetual lever, 31
Month wheel with indexing arm, 31
48 month wheel, 48
Day wheel, also ratchet toothed, 7
Lunar Indication: Mounted on the same sub-plate and the calendar work. The moon dial wheel has 59 ratchet teeth, the wheel is of gold with a background of blue enamel with the two 'moons' and 16 'stars' showing through. The indexing is effected twice per day so that it completes one revolution in 292 days.
Winding System: A standard side-set rocking bar keyless work.
Dimensions: Diameter 49.7 mm, height 18.3 mm, pillar height 3.3 mm.
Provenance: Formerly in the Ilbert collection, purchased by Ilbert from Malcolm Gardner in November 1941.
This ebauche is uniformly of the highest quality. The basic frame is of English origin but the complications have been added in Switzerland.
- Not on display
Latest: 4 (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.1389 (Ilbert Collection)
Previous owner/ex-collection number: Q85 (Ilbert Ledger)