- Museum number
MOVEMENT AND DIAL OF A LEVER CHRONOGRAPH WITH CENTRE-SECONDS.
1/2 plate; going barrel; keyless winding, rocking-bar hand set; ratchet-tooth lever escapement; fly-back chronograph.
White enamel canister dial; hours I-XII, minutes 5-60; centre seconds 0-300;
sunk subsidiary seconds 0-60 and sunk subsidiary chronograph minutes 0-60.
- Production date
Diameter: 41.60 millimetres (back-plate)
Diameter: 46 millimetres (dial)
Thickness: 13.60 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Army and Navy Cooperative Society (possibly Victor Kullberg).
London. c. 1900
Movement of a ratchet tooth lever chronograph
Signature: On the back plate 'Army and Navy Cooperative Socty Ld 105. Victoria Street LONDON SW No. 6546', the number 6546 also on the dial.
Case: Missing. The movement was held in the case by a large locating stud and a single dog-screw.
Dial & Hands: A flat canister dial with a silver rim. The dial has sunk subsidiary seconds and minute recording dials. The outermost ring on the main dial, encircling the minute ring, has 1/5th second divisions. Blued-steel spade pattern hour and minute hands, blued-steel subsidiary hands and a blued-steel centre-seconds hand with counterpoised tail.
Dial-Plate: None intended.
Dust-cap: None intended.
Ebauche Marks: 16 x 0
Frame: Half-plate construction, the back plate supported by three turned pillars and secured by screws. The front plate has a flanged edge and is deeply recessed for the under-dial work. On the inside of the front plate, a separate cock for the fourth wheel and a bridge for the escape wheel and pallets.(1) On the dial side of the front plate is a large bridge with bearings for the third and fourth wheels and all the escapement. The inside of the back plate is the numbered 6546. The back plate is recessed on the inside and has a raised portion on the outside to accommodate the barrel. Although the raised portion is chamfered, the barrel and great wheel protrude beyond the edge of the plates.
Barrel and Mainspring:
Barrel: going barrel with 5-turn Geneva stop work on the cap. Barrel internal diameter 18.8 mm, height 3.2 mm.
Mainspring: height 2.9 mm, thickness 0.21 mm.
Barrel Arbor: diameter 6.0 mm, snailed.
Train: A high quality train with high count pinions. All the wheels gilded and with six crossings. The pinion head of the centre wheel is screwed onto the arbor.(2)
Jewelling: Jewelled bearings from the centre wheel onwards. Ruby endstones for the escapement except for a diamond in the balance cock. The train jewels are all bombé. All the jewels in screwed settings except for those on the dial side of the front plate for the centre third and fourth wheels which are rubbed in.
Escapement: A right-angle layout ratchet tooth lever escapement with short lever, double roller and D-shaped impulse pin. The dart is made from gold. The enclosed pallet stones have convex impulse and locking faces. The polished brass escape wheel has three crossings.
A mixed impulse escapement.
No. of teeth embraced 32.
Balance & Spring: A split bimetallic balance with gold compensation screws and quarter nuts. Balance diameter 17.5 mm, thickness 1.8 mm. A free sprung blued-steel flat spiral spring of 15 tight coils with a terminal curve attached to a rectangular steel collet on the balance staff and a polished steel stud on the balance cock table. The balance cock has been bent down in an effort to make the watch function with its broken balance staff.
Means of Regulation: Free sprung, thus the quarter screws must be used for regulation.
Train Counts and Beat Rate:
Great wheel 92 (Barrel)
Centre wheel 96 pinion 14
Third wheel 75 pinion 12
Fourth wheel 80 pinion 10
Escape wheel 15 pinion 8
Beat rate: 18,000
Motion work: Cannon wheel 35
minute wheel 35, minute pinion 8
hour wheel 96.
Winding System: Side-set rocking bar keyless work.
Chronograph mechanism: An instantaneous minute-recording chronograph. The action is controlled by a pillar wheel and a series of levers pivoting on pillars, each with its individual return spring. The whole of this mechanism is fitted on the front plate under the dial and is operated by a single push-piece which passed through the pendant. The drive for the chronograph is taken from the fourth wheel via a jockey wheel in permanent mesh with the fourth wheel. Mounted on the same arbor as the jockey wheel is a steel wheel having fine teeth on its edge, corresponding with those of a brass wheel at the centre which carries the chronograph centre seconds recording hand. The jockey wheel is caused to move towards or away from the central seconds recording wheel by the pillar wheel acting on the other end of the bar on which it is pivoted. This makes or breaks the transmission between the fourth wheel and the centre.
Fitted on the same arbor as the chronograph centre-seconds recording wheel are two cams, one for the return to zero of the seconds hand, the other to raise a lever, which exactly at the minute as shown by the seconds hand, allows the lever to fall and advance the minute recording wheel and hand by one minute. This is the most accurate system devised for advancing the minute recording hand as nearly as possible to the minute. It is designed to avoid the confusion that can occur when the seconds recording hand is stopped at or near the minute and there is uncertainty as to whether the corresponding minute has been recorded by the other hand. If carefully made and adjusted the minute recording hand can be advanced during the last fifth of a second before the beginning of the next minute shown by the seconds recording hand.
Movement: diameter 44.8 mm, height 13.0 mm, pillar height 3.2 mm.
Provenance: Formerly in the Ilbert Collection. Purchased by Ilbert from Jauncey in 1933.
(1) The construction, design and superlative quality of this watch is similar in some ways to the work of Victor Kullberg who may have supplied it to the Army & Navy Cooperative Society for retail. It should be noted, however, that the serial number on the watch does not correspond to those recorded in the Kullberg work books now in the Guildhall Library, London and there is no evidence in those records that Kullberg supplied them with watches. It is equally likely that the Army & Navy Cooperative Society could have been supplied with watches of this quality by S. Smith & Sons of the Strand London.
(2) This type of safety pinion is designed to prevent damage to the pinion in case of mainspring breakage. The theory is that the shock will simply unscrew the pinion head. This feature is most likely to be found in American watches and is an unusual inclusion in an English watch. One such example in the British Museum collections is to be found in a watch by The American Waltham Watch Co., no.3794189 (reg. no. 1958,1201.905 (CAI-905)) which will appear in the forthcoming Volume VB of the 'Catalogue of Watches in the British Museum'. The watch has the legend 'SAFETY PINION' engraved on the back plate to draw attention to this feature.
For another watch retailed by the Army & Navy Cooperative Society, No. 9019, see cat. no. 225 (registration no. 1972,0903.8).
- 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.0908 (Ilbert Collection)
Previous owner/ex-collection number: N96 (Ilbert Ledger)