- Museum number
MOVEMENT EBAUCHE OF A LEVER CHRONOGRAPH WATCH WITH MINUTE REPEAT.
Three-quarter plate ebauche; keyless, Swiss cadrature.
Slide-operated minute-repeat striking on two wire gongs.
Lever escapement; components not fitted.
Chronograph mechanism under dial mounted on spotted steel plate.
Keyless winding and hand-set.
- Production date
Diameter: 43.50 millimetres (movement)
Thickness: 16.60 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Maker unknown but was a Robert Gardner calibre.
England and Switzerland, late 19th / early 20th century
Ebauche for a minute repeating chronograph with a lever escapement.
Case: Not fitted but the alignment of the arbors for the hands and the relative position of the keyless mechanism suggest that it was a hunter case with the pendant at III o'clock and with a push-piece at XII to operate the chronograph mechanism.
Ebauche Marks: none
Frame: The half plate movement is fitted with fully finished repeating work and has a sub-plate with fully finished chronograph work. The back plate is supported by three turned pillars and secured by screws. There are cocks for the fourth, escape and pallets and the balance cock is fitted, this has a micrometer index. There is a raised portion on the back plate to accommodate the barrel. The repeating work has its own bridge and cock. There is also a separate cock for the pallets of the speed controlling escapement. The back plate is scratched inside 66. The front edge of the front plate is engraved with minute divisions within the 15 minute positions marked with a dot.
Barrel and Mainspring:
Barrel: going barrel, the cover with 5-turn nickel silver Geneva stopwork. Internal diameter 16.4 mm, height 2.65 mm.
Mainspring: not fitted.
Barrel Arbor: diameter 5.7 mm snailed.
Hooking: a round hook not yet reduced in height on the inside.
Train: Plain brass centre, third and fourth wheels each with six crossings. The pinions are completely finished. The fourth wheel has an extended arbor to carry a subsidiary seconds hand.
Jewelling: Four jewels are fitted, two are in the chronograph sub plate for the minute recording wheel and two are for the intermediate chronograph wheel.
Escapement: not fitted.
Great wheel 92 (Barrel)
Centre wheel 80 pinion 14
Third wheel 75 pinion 10
Fourth wheel 70 pinion 10
Motion work: cannon wheel 35
minute wheel 35, minute pinion 8
hour wheel 96.
Minute Repeat Mechanism:
A slide operated minute repeat mechanism with rack and pinion driving circular rackes for the quarters and minutes. There are separate snails for the hours, the quarter and the minutes. The minutes are controlled by a four-lobed snail with 14 steps on each lobe. The system has a fixed mainspring which drives a four wheel gear train of solid brass wheels. In contrast to the going train where there is no mainspring, here the spring is installed and set up ready for operation. The speed of striking is regulated by a form of recoil escapement. The train terminates with a recoil type escape wheel which acts with a pair of pallets. Fixed to the pallet arbor is a weighted arm which oscillates rapidly as the pallets are impulsed by the escape wheel. The weighted then banks against an adjustable spring to achieve the desired operating speed. Two hammers strike the hours quarters and minutes on two circular gongs of round cross section.
Repeat Barrel and Mainspring:
Barrel: a standing barrel, internal diameter 7.3 mm, height 1.9 mm
Mainspring: height 1.7 mm, thickness 0.10 mm
Barrel Arbor: diameter 3.1 mm, snailed
Repeat train count:
Great wheel 50 (barrel)
Second wheel 38 pinion 6
Third wheel 32 pinion 6
Escape wheel 15 pinion 6
Chronograph Mechanism: A centre-second chronograph mechanism mounted on a steel sub-plate secured by three screws to the front plate of the movement. This steel sub-plate is finely grained and spotted. A castle wheel performs the three functions; stop, start and return to zero. Mounted on the extended fourth-wheel arbor is a fine toothed chronograph wheel with five crossings and approximately 200 fine triangular teeth. This wheel meshes with an intermediate chronograph wheel mounted on a pivoted lever which pivots at one end around the fourth wheel bearing and at the other end engages in the castle wheel. Operating the plunger moves the castle wheel which moves the pivoted lever to engage or disengage the mesh between the intermediate chronograph wheel and the centre mounted chronograph wheel which carries the centre-seconds hand. The fly-back function is provided by a cam mounted on the arbor of the centre-seconds hand. A second single-step cam mounted on the centre-seconds arbor indexes a minute recording wheel with sixty ratchet teeth intended to carry the minute recording hand. A further cam on the minute-recording arbor perform the fly-back zeroing function.
Winding Mechanism: Side-set rocking bar type. Unusually the barrel ratchet wheel bears an arrow which shows the direction in which it should be turned when screwing it onto the barrel arbor.
Dimensions: diameter 43.5 mm, height 16.3 mm, pillar height 2.7 mm.
Provenance: Formerly in the Ilbert collection. Ilbert acquired it from Robert Gardner 30/9/1931.
A Robert Gardner calibre to which he had the minute repeat and chronograph mechanisms fitted in Switzerland in 1920.
Although similar to the system described in François LeCoultre 'Complicated watches', p. 156, in this example L. E. Piquet's isolator intended to cut down drag on the quarter jumper is not fitted.
The finish on these wheels and the fact that the crossings are chamfered mark them out from the going train wheels which are unfinished.
- Not on display
Latest: 3 (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.1465 (Ilbert Collection)
Previous owner/ex-collection number: L103 (Ilbert Ledger)