- Museum number
Full-plate movement with fusee
Lever escapement; compensated balance.
White enamel dial, gold hands.
- Production date
- 1786 (case)
Diameter: 55.80 millimetres (case)
- Curator's comments
Text from 'Watches', by David Thompson, London, 2008, p. 98-99.
GOLD CASED WATCH WITH DETACHED LEVER ESCAPEMENT
SIGNED: 'Josiah Emery, Charing Cross, London 1089'
Thomas Mudge's pioneering work in the 1750s and 1760s created a new type of escapement for portable timekeepers: the detached lever escapement. His first example was incorporated into an experimental bracket clock that he made around 1750. His first watch with such an escapement was made for Queen Charlotte in 1769, and delivered some time in 1770. Mudge's escapement was in some ways based on George Graham's dead-beat escapement for clocks, but placed a lever between the escape wheel and the balance that would lock and unlock as well as imparting impulse to the balance. This would finally allow the oscillating balance to swing unencumbered except when it was acting with the lever to carry out the three functions, hence the name detached.
However, Mudge's original concept was a complicated one, difficult to replicate, and it was not until the late 1770s/early 1780s that the escapement was developed by, among others, Josiah Emery. He employed a highly skilled escapement maker, Richard Pendleton, and the result of their combined efforts was a series of pocket watches incorporating Emery's escapement.
Josiah Emery had come to London from his native Switzerland probably in the 1750s and established himself as a watchmaker in Warwick Street, 'Opposite Hedge Lane', in Soho. The son of Jacques Emery and Susanne-Marie Gammeter, he was baptized at Etagnieres near Chardonne on 11 November 1725. In adult life, his reputation as a watchmaker quickly grew and thus it is perhaps not surprising that he should gain the attention of Mudge's patron and supporter Count Maurice von Brühl, who would spur Emery on to develop Mudge's escapement. On the matter, Emery said:
"About seventeen or eighteen years ago Count Bruhl repeatedly urged me to make him a watch upon an escapement Mr. Mudge had invented. I for a long time successively answered that Mr Mudge was the properist person for such an undertaking; for to own the truth, I doubted whether it would be possible to ever make a common sized pocket watch with an escapement on so large a scale. But the Count not contented with my repeated refusal, at last prevailed upon me. It was then he brought me a large frame, like a clock escapement, but at the same time he gave me no rules concerning it, nor any of the smallest hint of the construction of Mr Mudge's watch; nor did I ever see the said watch till many years after (for the Queen had it) and his Majesty himself did me the honor to shew it to me."
Between 1782 and 1786 Emery produced a series of lever escapement watches, at least thirty-eight of which were made. This particular example is signed 'Josiah Emery, Charing Cross, London 1089' on the movement. The 18-carat-gold case is hallmarked 'London 1786' and bears the mark, 'VW', of the casemaker Valentine Walker. The white enamel dial is of the so-called 'regulator' type. The minutes are marked around the outside and there are separate subsidiary dials, for hours above the centre, and for seconds below. The movement is characteristic of Emery's watches, with finely gilded plates and a decoratively engraved bridge on the back plate for the balance. The balance is of a type designed by John Arnold and commonly known as the 'double S', referring to the two S-shaped bimetallic compensation devices attached to the balance arms, designed to obviate timekeeping errors caused by changes in temperature.
Comment from Richard Good, Catalogue of Watches in the British Museum. Vol. V (Unpublished manuscript)
Made by Josiah Emery
Gold cased stop-watch with an early lever escapement
Signature: On the back plate and repeated on the dust cover 'Josiah Emery Charing Cross London 1089'. Across the centre of the dial 'EMERY LONDON'.
Case: Gold consular case with the London hallmark for 1786, the casemaker's mark VW (1) and a duty mark. The seven-knuckle book hinge combined for both front and back of the case which is without springs. A chased stirrup pendant. The centre of the back has a chased medallion with a crest, almost erased.(2)
Dial & Hands: The flat, regulator style dial is retained by two dog screws set in the ends of the feet. The hands are of blued steel, the minute hand in the centre with the hour hand above and the seconds hand below. The hands are of an unusual design.
Dial-Plate: Held by three screws under the dial, and the movement retained in its case by three dog screws in the dial plate.
Dust-cap: A gilded brass dust-cap attached by bayonet lugs to pieces on the inside of the case. Made in two parts, a deep-sided drum with one end open, the other raised over the balance cock, and with three holes drilled in it; one for the dust tube around the winding square, the other two for pegs on the back plate of the watch to prevent the drum from turning. The other part of the dust cap is a moulded ring adjusted to turn free through a short angle on the drum. It carries the bayonet fixing to retain the cover on pegs set in the edge of the case.
Ebauche Marks: None
Frame: A full plate layout, with no separate bridge for the barrel. The back plate is supported by four turned pillars, three retained by pins and the fourth by a countersunk blued-steel screw. A separate bridge on the front plate provides bearing for the third and fourth wheels. The front plate is pierced by an almost square hole to admit the cast potence which is screwed to the underside of the back plate and carries the lower escape wheel bearing. The two rectangular slots diametrically opposite each other in the edge of the front plate are for the dial feet. The balance bridge on the back plate is engraved with foliate scrolls.
Fusee, Barrel and Mainspring:
Fusee: 6-turn fusee with Harrison's maintaining power with a brass maintaining ratchet wheel. The maintaining detent spring is partly under the great wheel, both it and the detent are highly polished. The detent return spring operates on a pin on the detent. The stop-piece of the stop-work is mounted in an ornately pierced block.
Barrel: flanged at the cover end and reduced at the other to clear the great wheel. Internal diameter 17.7 mm, height 5.2 mm. The set-up return spring and tail made from a single piece of steel (see also cat. no. 10 (registration no. 1958,1201.1118)). The mainspring is set up by means of a square male key which fits a squared hole in the end of the barrel arbor on the front plate end.
Mainspring: height 5.0 mm, thickness 0.20 mm.
Barrel Arbor: diameter 5.6 mm, not snailed.
Train: All the wheels gilded, the pinions and arbors highly finished. The centre wheel solid, the third and fourth wheels with six crossings.
Jewelling: All the pivots of the going train arbors, with the exception of the centre pivot in the back plate and the fusee arbor pivot in the front plate, are in pierced jewel bearings. The flat jewels with oil reservoirs are set in burnished brass rings, themselves set in recessed holes and retained by polished screws. The pivots of the escapement and balance staff are in pierced jewels with endstones similarly set and fixed.
Escapement: An early example of the lever escapement, without draw. All the lift is on the pallets which are planted between the back plate and a separate bridge screwed and steady pinned to the underside of the back plate. The banking pins are set eccentrically in brass plugs set flush in the back plate and with screwdriver slots on their upper sides. These have been gilded over, presumably after adjustment at the ebauche stage and not intended to be altered later. The run to banking is very small, and the drops just sufficient to clear the tooth tips. The two halves of the impulse roller are on different levels and can be rotated relative to each other to precisely adjust the shake in the fork, which is somewhat similar to Mudge's fork and roller action. The escape wheel has four crossings.
Balance and Spring: A gilded brass flat four-arm balance held on a collet on the balance staff by two screws. Two gold timing screws in brackets are riveted to the balance rim and held with clamp screws. The thermal compensation is similar to John Arnold's 'double-S' system and is mounted on a separate blued steel frame screwed to opposite arms of the balance (3). Each of the flat S-shaped bimetallic units is made of two separate U-shaped sections riveted together, and fixed to the steel frame with a screw. The hollow gold compensation screws fit onto steel studs on the free ends of the S units. Balance diameter 23.1 mm, height 2.1 mm.
The blued-steel helical balance spring, of which about 7 2/5 turns are used, is without terminal curves. The lower end of the spring is clamped to an oval brass collet, the upper end to an adjustable overhanging stud. A flanged screw set in the foot, the flange in a groove in the back plate enables the stud to be advanced towards or away from the balance between four short positioning pins standing on the back plate.
Train Counts and Beat Rate:
Great wheel 62 (fusee)
Centre wheel 80 pinion 16
Third wheel 75 pinion 10
Fourth wheel 68 pinion 10
Escape wheel 18 pinion 8
Beats per hour: 18,360
Cannon pinion 10
minute pinion 12 minute wheel 40
hour wheel 36
Stop-Mechanism: Operated by a short lever on the front plate carried on an arbor pivoting in the frame. On the end of the arbor against the back plate is screwed a right-angled arm. The free end of this arm is wedge-shaped and acts on a polished steel spring screwed to the underside of the back plate and carrying a stud in a hole in the back plate. The hole is positioned under the rim of the balance on which the stud acts.
Case: diameter 55.8 mm, thickness 25.0 mm (over the glass).
Movement: front plate diameter 40.4 mm, back plate diameter 40.5 mm, frame height - between 9.93-10.0 mm, pillar height 0.00 mm.
Dial plate diameter 45.9 mm.
Duke of Sussex collection, sold by Christie's on 4 July 1843, lot 49.
Ilbert Collection, Purchased by Ilbert from Malcolm Gardner in 1933.
(1) Valentine Walker watch-case maker of 8, St. Johns St. Rd., Islington until 1796 then at 12, Kirby St., see Grimwade, 1982 p. 324.
(2) The crest appears to have been polished out, presumably at the request of a subsequent owner of the watch.
(3) Although this watch bears Emery's name, there is little doubt that the escapement was made by Richard Pendleton. There is a reference in Rees's Cyclopedia, 1819-20. p. 18, to the fact that the workmen employed by John Arnold making 'S' balances had left him and were working for Emery. Arnold started to use the 'S' balance in about 1779 and continued until 1782 during which time, according to Rees, about 40 were produced. Emery's earliest use of the 'double S' balance appears to be in about 1782, confirming Rees's statement. A further reference in Thomas Mudge Junior's, A Description with Plates, 1799 p. xxxix, confirms that Richard Pendleton was employed by Josiah Emery in the making of lever watches. For more details see Cat. no 10, note 3 (registration no. 1958,1201.1118).
For a similar watch see Anthony G. Randall, 'The Time Museum Catalogue of Chronometers', Illinois U.S.A. 1991, cat. no. 61. This watch by Josiah Emery, no.957 has a London hallmarked case of 1783.
For a comprehensive commentary and analysis of the life and work of Josiah Emery and his association with Richard Pendleton see J. Betts, Josiah Emery, in five parts, 'Antiquarian Horology', Vol XXII, 1996, pp. 394-401, 510-523. Vol. XXIII 1996-1997, pp. 26-44, 134-150, 216-230.
Bibliography: J. Betts, Josiah Emery, in five parts, 'Antiquarian Horology' Vol. XXIII (Winter 1996), part four 'The Surviving Lever Watches' p.141.
- On display (G39/dc14/no49)
- 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.
This watch appears in the sale of the collections of the Duke of Sussex, Christie's, 4th July 1843, lot 49. Sold to Brown for a hammer price of 11 Os 6d.
- Britain, Europe and Prehistory
- Registration number
- Additional IDs
Previous owner/ex-collection number: CAI.1645 (Ilbert Collection)
Previous owner/ex-collection number: P71 (Ilbert Ledger)