- Museum number
MOVEMENT AND DIAL OF A LEVER WATCH.
Full plate; fusee with Harrison's maintaining power.
Lever escapement; single pallet with two escape wheels; overbanking stud; compensation balance.
Enamel dial with large intersecting subsidiary seconds.
Gold hour and minute hands; blued-steel seconds hand.
- Production date
Diameter: 44.40 millimetres (back-plate)
Diameter: 50.20 millimetres (dial-plate)
Thickness: 19.60 millimetres
- Curator's comments
- Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by John Grant
London, c. 1798 (1)
Movement of a watch with an early lever escapement
Signature: On the back plate and barrel bridge 'GRANT Fleet Street No 1736' and on the dial 'GRANT LONDON'.
Dial & Hands: A flat dial with a slightly offset hour and minute circle. The subsidiary seconds circle, which occupies all the available space in the lower part of the dial, intersects the hour and minute circle. Three screws in the dial plate pass into wide feet in the dial to secure it. The signature 'Weston' is fired into the counter-enamel.(2) Gold spade-pattern hour and minute hands, blued-steel seconds hand with a long tail.
Dial-Plate: The dial-plate is fixed to the front plate by three screws which are accessible only after the dial has been removed. There are three slots in the edge of the front plate for the dial feet. Scratched on the dial side of the dial plate is the inscription 'Grant 1736' with another scratching which is undeciphered.
Dust-Cap: None intended.
Ebauche Marks: none.
Frame: Full-plate construction with four turned pillars, the back plate secured by screws, two of them also securing the barrel bridge. There is a long bridge on the front plate with bearings for the fusee, third and fourth wheel arbors. The case catch spring is planted on the opposite side of the front plate but the catch still works partly under the bridge. The balance cock foot extends to the edge of the back plate. Both balance cock and barrel bridge have matched engraved foliate decoration and there is a large grotesque mask on the balance cock table. Scratched on the front plate under the dial is 'JW 6 91' then added below '6, 93' and '5, 95', the last number '2,01'(3) scratched over an earlier inscription 'D1'?
Fusee, Barrel and Mainspring:
Fusee: five-turn fusee with Harrison's maintaining power, the maintaining ratchet wheel brass, the long detent return spring planted with its foot almost touching the case.
Barrel: flanged at the cover end, internal diameter 17.3 mm, height 5.0 mm., a late example of the use of tangent-screw set-up.
Mainspring: height 4.6 mm, thickness 0.21 mm.
Barrel Arbor: diameter 5.5 mm, not snailed.
Going train: Gilded wheels, the second wheel, slightly off-set from the centre, is solid, the third and fourth wheels have four crossings. The fourth wheel is a contrate wheel which drives the escape pinion which is set at right angles to the train.(4)
Jewelling: Jewelled bearings for the fourth wheel and escapement, with endstones for the lever and balance. The jewelling for the pivots of the escape wheel arbor appears to consist of pierced jewels and endstones set inside short blind tubes but this cannot be verified as the tubes cannot be dismantled. The other jewels are in screwed settings. The upper balance endstone is a ruby in a blued-steel screwed setting.
Escapement: Two-plane lever escapement with two polished steel escape wheels both mounted on the arbor of the escape pinion with their axis at right angles to that of both the lever and balance staff. The escape wheel is mounted between two potences both with bearing adjustments for optimum positioning of the wheel. In the fork and roller action the impulse roller on the balance staff is a small ruby tube set on a steel arbor which pivots in a brass frame on the balance staff. Safety action is provided primarily by a dart with a passing hollow cut out of the balance staff and also by short horns on either side of the notch. Banking is by screws set in the balance potence.
The pallets consist of a single segment-shaped piece of ruby held on the arm adjusted onto the pallet staff and working between the two wheels in a slot cut out of the back plate. There is no draw, the wheel teeth being locked on the concave inside radius of the piece of ruby. Impulse is given against the inclined planes, one at each end of the piece of ruby i.e. the lift is on the pallet. The escape wheel teeth are cut on the skew to present a very narrow rubbing surface to the pallet. A platinum counterpoise is fitted at the other end of the pallet staff. The pallet assembly gives the impression of being a prototype; it is crudely made and poorly finished and made from a number of separate pieces, unlike that of the Gartly watch (cat. no. 11 (registration no. 1985,1201.1200) which is made from the solid with what is obviously greater confidence.
Balance & Spring: Bimetallic two-arm balance with brass compensation weights secured by screws, and steel screws set in the rims at the ends of the arms. Balance diameter 24.2 mm, thickness, 2.1 mm.
A blued-steel flat spiral spring of 8 3/4 open coils, pinned to an overhanging stud. A brass piece pinned to the last coil of spring acts as an amplitude limiting device with a steel piece on the balance cock. There is also a pin on one of the balance weights pointing upwards. The system appears to have undergone some adjustment and no longer works though it appears that it was intended to operate when the balance amplitude reached 230E. The blued-steel index has a strong resemblance to that in the Gartly watch (cat. no.11). It registers against a scale on the top plate marked 24, 18, 12 and 6 reading from left to right.
Train count and beat rate:
Great wheel 63 (fusee)
Centre wheel 80 pinion 16
Third wheel 75 pinion 10
Fourth wheel 60 pinion 10
Escape wheel 15 pinion 6
Beats per hour: 18,000
Motion work: cannon pinion 12
minute pinion 14 minute wheel 48
hour wheel 42
Winding Mechanism: Key wound.
Movement: front plate diameter 46.5 mm, back plate diameter 45.2 mm, frame height 8.8 mm, pillar height 0.00 mm.
Dial plate: diameter 50.1 mm.
Provenance: Formerly in the Ilbert Collection. Purchased by Ilbert from Wartski in 1930.
(1) Another lever watch signed 'Grant Fleet Street London No.1479', in gold pair cases hallmarked London 1795, can be found in the collection of the Worshipful Company of Clockmakers, see Clutton and Daniels, 1975, cat. no. 456.
(2) William Weston, dial enameller of 23, Greenhill Rents, Smithfield, 1790 -1818, see Britten, 1982 p. 642. For another Weston dial see cat.no. 11.
(3) These numbers are obviously repair dates with the number of the month and then the year. For a time at least between 1891-1901 the watch was serviced at two year intervals by the same man.
(4) This gear train is similar to that found in a watch signed John Gartley (see cat. no. 11) except for the great wheel which has 63 teeth instead of 64.
The earliest surviving lever watch by John Grant was in the Atwood Collection in the Time Museum, Rockford, Illinois. The watch is signed 'Grant Fleet Street London No.1408' and is housed in a gold consular case hallmarked London 1788. For a full description see A.G. Randall, 'The Time Museum Catalogue of Chronometers', cat. no. 72. There is also a watch by Grant, no.1737 which has a silver case hallmarked London 1792, see Randall op. cit. p.186.
- Not on display
Latest: 2 (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.0962 (Ilbert Collection)
Previous owner/ex-collection number: N224 (Ilbert Ledger)