Experimental marine timekeeper

Henry Sully, Versailles, c.1724 No.8
Eight-day marine timekeeper movement ZBA2248

Case The timekeeper is now housed in a modern oak case, suspended from above in a modern brass gimbal. This mounting is based on the arrangement for Clock ‘C’ shown in an engraving in Sully’s Description abrégée du temps (Sully III). When the clock first surfaced in the horological world in 1997, it was only a movement, mounted to a horizontal board and protected under a glass case.

Dial and hands The 25mm (10-inch) Ø, brass dial has a silvered chapter ring with engraved roman hour numerals, arabic five-minute figures and diamond half hour markers. The finely matted and gilt dial centre has a calendar aperture below the centre and a seconds indication above. The chapter ring is attached by six feet, pinned from behind. The dial back has been relieved to make room for the rack tail, and circles have been scribed for the calendar advancing pallet. The earlier winding hole for the going train, which came through the matting on the right hand side of the dial centre, has been carefully plugged and matted, and the calendar ring, on the back of the dial, passes about one third of the way over this original hole.

The hands are polished, blued-steel. The minute hand is of a waisted-poker type, paired with a similar hour hand that originally took the form of a fleur-de-lis (the emblem of the French monarchy), now with the ‘ears’ broken off (probably during the French Revolution). The blued-steel seconds hand is also of a waisted-poker form with a counter-poised tail.

Movement The large, two-train, quarter-striking latched-plate movement has 5 knopped pillars, and originally had going barrels on both trains, but was adapted to have a fusee on the going side. There are numerous filled holes and plugs in the plates. The third and fourth wheels and the upper striking train all run under a sub-frame mounted within the main frame on four slender, baluster pillars screwed to the front plate.
At 1724, this is perhaps the earliest example of screwed pillars in clockwork. In the context of its period, the general level of finish is excellent. All of the movement parts are nicely flat polished. There is an amplitude scale mounted at the top of the backplate, each ten degrees stamped in arabic, alternately higher and lower on the scale, starting with 0 at the top centre, and going up to 60 on either side. The lower part of the scale also acts as the support for the rear pivots of the balance’s rear anti-friction wheels.

The backplate is stamped neatly around the upper opening: HENRY . SULLY. A . VERSAILLES . / INVENIT . 1721 . ET . FECIT . 1724 . On the lower part of the backplate are mounted the ratchet wheel and blued-steel click and click spring for the striking side, and a similar ratchet arrangement for the set-up of the going side barrel. The latches on the front plate have all been numbered with stamped figures, on both latch and plate (some have been re-numbered at a later date). On the dial side of the front plate, the post for the calendar’s 24-hour wheel has been repositioned. The front plate is scratched: Enderlin de Bale / fait en 1724 / Pour Monsieur / de Sully ; netoyes en Novembre, 1729 ; Ate. Mottet. / en decembre. 1827 / St germain : en Lay. ; m nerve Saint augustin N31 ; Alibert 1855 / Mai , &: Reparee le 5e Mars / 1952 / par A MAILLARD . Under the going train barrel the plate is scratched: toutlemonbe [sic] / octbre 1817 and 3 . Striking barrel scratched: Alibert 1855 , toutlemonde 22 fevrier 1811 ; seuus [?] Jules Gourand Septembre 1867 . The cap is scratched: Pinson le 4 marse / 1788.

The fusee was originally designed for a gut line but has been converted to chain, and back to gut, in the past. The cavity for the knot remains in the fusee, but the hole has been plugged, and there are three plugged holes in the barrel wall. The groove has also been recut for chain. It has a single steel click mounted accessibly on the great wheel.

The high-numbered, five wheel (incl great wheel), 8 day going train, employs a contrate as the fourth, driving the escape wheel at 90°. The signed going train mainspring is of blued-steel and has a round hooking hole with a fixed hook in the barrel. The stopwork is of conventional English type, activated by the last turn of the gut on the fusee.

The 8 day, two-bell, quarter-striking train is controlled by rack and snail. The design is continental, and of a type published by Antoine Thiout in 1741 [FN: Thiout, Vol.2, plate 18]. The snail incorporates one, two and three blows for the quarters. A mechanism shifts the hammer with its arbor from the low bell (for sounding the hours) to a high bell (for sounding the quarters). The shift is actuated by a ramp on the minute wheel that tilts a ‘see-saw’ lever (with a roller acting on the ramp) to move the hammer arbor sideways for the hour blows. A double pallet on the front pivot of the gathering pallet wheel acts on the underside of the rack which has two sets of teeth, one on the underside for being gathered and one on top for being locked on the rack hook.

The movement parts are stamped 8 throughout: the inside of the backplate, the inside of front plate, the inside surface of the anti-friction (a/f) wheel subframe, the inside of the train sub-frame, the lower potence for the escape wheel, the front escape wheel cock, both a/f wheels, the upper and lower cocks for the hammer-shift arbor, the fusee, the great wheel, the centre wheel, the third wheel, the contrate wheel, the cannon wheel, the minute wheel, the hour wheel cock, the lifting lever cock, the minute wheel cock, the rack cock, the striking great wheel (on the barrel), the stop-work cover, the stop-work pawl, the striking ratchet wheel, the intermediate wheel, the pin wheel, the 5th wheel of the striking train (remains of an 8 on edge of crossing), the balance bridge, the balance bridge bar, the back of the dial plate and the back of the chapter ring.

There are two dots on the striking ratchet wheel, the striking intermediate wheel, and on the inside of the backplate, but by the plugged holes where the barrel and the intermediate wheel were originally positioned for the going train. One a/f wheel on that (going) side of movement is also marked with two dots. There is one dot on an a/f wheel on the other side of the movement and on the going set-up ratchet which is also scratched: M. It seems probable therefore that the barrel now used for the striking, which has high quality stop-work, and the striking intermediate wheel, were taken out of the going train and were re-purposed for the striking train, being too good to waste. The 24 hr calendar pinion and wheel are dot-marked for position on the underside. The high number of plugged holes suggests the trains have been replanted several times, and some arbors that originally ran between the plates were shortened to run within the sub-frame at a later date.

Escapement & balance The escapement is of Sully’s own dead-beat pinwheel type, employing a single brass wheel with radial teeth. The balance staff carries two steel disc pallets with angled impulse planes. This design, of which Sully was extremely proud, was a simplification of the Debaufre-type that Isaac Newton had shown him. In Newton’s Debaufre watch, two escape wheels, fixed together side-by-side, acted on a single pallet. Sully’s two steel discs, which form the pallets, each have a second impulse slope cut in a different position. This allows a different degree of impulse to be introduced, by removing the pallets and turning them over on the balance staff (a sharper incline on the pallets delivers a greater force, but over a shorter span of the balance’s swing. The same energy is imparted to the balance, only more ‘suddenly’).

The large, plain brass balance has four slightly tapered arms each beveled on both sides giving a flattened diamond cross-section. Plugs in the balance rim at the ends of the arms suggest something was attached to the periphery at an earlier date. A flat circular brass ring has been added to the balance, fixed with four screws, probably to increase its mass during manufacture. Mounted on the rear pivot of the balance staff, beyond the a/f wheel supports, is a brass collet carrying a blued-steel indicator that points to the semi-circular brass amplitude scale mounted above. The collet also serves as the connecting point for the restoring force linkage, via a fine Cardan joint. This pivoting joint, in turn, is connected to a vertical brass wire that passes down the backplate to the base of the movement and connects to a second Cardan joint that runs on a small horizontal arbor that is pivoted under a cock on the end of a weighted lever. The lever itself is what gives the movement design it name, ‘Pendule à levier’. In lieu of a balance spring, gravity, acting on the rising and falling lever, provides the restoring force for the balance, through the linkages just described. The lever itself is pivoted outside the backplate in the lower left corner, and has fine pivots running in brass holes fitted with dovetailed steel end-pieces. On the other end of this lever, projecting out to the left of the movement, is an adjustable counterweight in the form of a brass ball threaded on a brass rod. Screwing the ball in or out alters the restoring force of the lever. The ball, thereby, provides the primary timekeeping regulation.

History Oral tradition suggests that this timekeeper was purchased from a watchmaker in Versailles by a M. Le Soufaché, who died during the First World War. It then passed into the possession of a M. X. Lavril, whose relatives consigned it for sale at Drouot Richelieu, by Millon & Associes, in Paris, in December 1997 [Ref: Millon & Associes, Drouot Richelieu, Paris,12 December 1997, lot 116.] At the time it was only a movement, mounted on a wooden base with a fitted glass cover. On 23 October 1999 it again appeared at auction, this time at Antiquorum, Geneva, [Ref: Antiquorum, The Longitude at the Eve of the Third Millenium, Geneva, 23 October 1999, lot 2]. By this time it had been taken off its base and placed in a replica of the housing illustrated for clock ‘C’, which included an oak case in brass gimbals, arranged to be suspended from a wooden beam. Charles Frodsham & Co acquired this important timekeeper for the NMM in September 2001, with the financial assistance of The Heritage Lottery Fund, The Worshipful Company of Clockmakers, The Weston Foundation, Dr George Daniels and The National Art Collections Fund [FN: Read, Matthew, The Sully Timekeeper, 2001 Annual Review, NACF, London 2002, p.111].

Object Details

ID: ZBA2248
Collection: Timekeeping
Type: Marine chronometer
Display location: Not on display
Creator: Sully, Henry; Sully, Henry
Date made: 1724
Exhibition: Time and Longitude; Ships, Clocks & Stars: The Quest for Longitude
Credit: National Maritime Museum, Greenwich, London. Acquired with the assistance of the Heritage Lottery Fund, The Art Fund, the Worshipful Company of Clockmakers and the Garfield Weston Foundation.
Measurements: Display: 550 mm x 675 mm x 290 mm;Overall: 105 mm x 95 mm x 47 mm x 23.5 kg
Parts: Experimental marine timekeeper

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