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3194

ZAA0229
Timekeeping

Object connections:

Collection Timekeeping
User collections The Board of Longitude by Richard_Dunn
Gallery locationROG (Floor plans)

Object details:

Object ID ZAA0229
Description Breguet et Fils, Paris, c.1821 No.3194 2 day marine chronometer in mahogany box For biographical details of the firm of Breguet of Paris, see pp.xxx Box/Mounting Two-tier, plain mahogany box measuring 175mm high, 225mm wide, and 192mm deep. The top of the box has an inset lid with side-pin hinges allowing it to open to about 120°. The lid is inlaid with a brass, diamond-shaped plaque, engraved: “3194”, and opens to a circular glazed panel retained with narrow brass bezel, screw-fixed from the underside. The front of the upper half has a push button brass catch for the lid with brass, circular escutcheon and brass spring inside the upper half to ‘jump’ the lid open when the button is pressed. The lock on the lower half (usual French-type with double bolts and pins), has an oval, brass escutcheon. The box has a full-width, ‘butt’-type, hinge and a brass strut on the right hand side, restraining the upper half to 90°opening. There is a raised step running around the inside of the junction on the lower half, mating with a rebate in the junction of the upper half and forming a dust seal when closed. The box fittings are similar to the standard French type, with brass drop handles on the sides and lacquered brass gimbals. A narrow, straight-sided bezel is retained with two side screws and has a concave, silvered-brass sight ring and beveled flat glass over the dial. It is scratched inside: “3194” and “3200”. The centre body of the movement-housing doubles as the brass edge of the movement and has a barleycorn knurled beading running round the outside. Both bezel and bowl are fixed to it with a pair of screws. The thick, oval gimbal ring has a concave inner edge to the upper surface, and two flat brass arms can be swung in from the rear left and front right corners of the box to engage with blocks on the bowl, securing the gimbals (original arms now missing). When these arms are in place and the lid is closed, cast brass pegs fixed up inside the upper half of the box prevent them from swinging open. When these arms are not in use they are swung out and stowed on little brass pillars on the edge of the box. The heavy brass bowl has an upstanding beading on the base, the two winding holes within both engraved with direction of wind arrows. There is a small plain hole drilled into the edge of the beading, with no apparent function. The later, English-type ratchet key (rising ratchet now pinned solid) is stowed in a standard, Breguet-type boxwood socket in the rear right of the box, the original retaining fork fixed up inside the upper half which secured the original key in place now missing. In the right and left sides of the lower half of the box there are vertical holes going through to the base with Breguet-type wood screws to fix the box to a wooden surface when in use on board ship. The underside of the box is plain, without baize covering. Dial and hands The 98.5 mm Ø, engraved and wax-filled, now English-silvered dial is fitted snugly in a rebate in the front of the brass edge, fixed with one screw at the top of the seconds dial, into the train bridge beneath. At the 6 o’clock position, a locating pin projects through the brass edge and engages with a notch in the edge of the dial. The movement is attached to the brass edge with three steel screws from the inside. The subsidiary hours and minutes dial has roman hour numerals and arabic ten-minute figures with a large seconds dial below having arabic ten second figures and with straight batons at five-second intervals. The dial is signed across the centre: “Breguet et fils Hgers de la Marine / Royale / No.3194 ”. Above the upper dial is engraved: “K2”. On the left of the upper dial is a balance locking lever (now inoperative) marked: “BALANCIER / Fixe / Libre”. Pencilled on the back of the dial is “87/8523”. It is also scratch marked “3194”; “DENT/762”; “87/8523”, and above this “S,2,93”; There is a blind hole drilled behind the 8 o’clock position on the dial, and near the center of the dial there is a shallow, turned sink, about 4 mm in diameter, with a raised button not quite in its centre. Blued steel demi-lune hands with a fine, blued steel pointer seconds hand with a solid counter-poised tail. Movement Breguet Grande Horloge Marine format double-barrel calibre movement with the train mounted under a bridge (fabricated from three parts) on the front of a central brass plate. The going barrels have all associated parts marked with one dot (on the barrel nearer the escapewheel), and two dots (on that nearer the balance cock foot). The barrels are mounted on a large double-cock on the rear of the plate. Although this casting is of rather poor quality, with a large number of small blow-holes evident, the general level of finish of the movement is high, with most movement parts flat-polished. The back of the main plate is stamped “3194” near the foot of the barrel cock and is scratched with “#” near the 1 dot barrel pivot and “ x 4511”[?]. The going barrels have spring-clicks alongside the ratchet wheels on the cocks, and brass and steel Breguet-type stopwork mounted on the caps of both barrels, the steel bearing of the stopwork forming the pivot in the cock. There is a four-wheel train, the greats on the barrels both meshing with the second (‘centre’) wheel in a straight line. All the train holes, including barrel arbor holes in the plate and cock, have been plugged and repositioned during manufacture. The rear pivot of the second wheel is carried by a sub-cock fixed by two screws to the underside of the barrel cock and has a steel coquerette. The rear pivots of the third and fourth wheels both have a steel endplate fixed to the main plate and the fourth wheel pivot hole is a separate brass bush, fixed in the plate. The wheels are all brass with the fourth wheel run in a cock on its lower pivot. There is a meshing inspection hole by the 2nd/3rd pivot in the main plate and by the 3rd / 4th pivot in the bridge. The top surface of the barrel cock is scratched “R”. The one-dot arbor is scratched: “3194” and the one-dot barrel has “#” scratched on the base. The two-dot barrel has one dot on the base and is scratched: “R”. The one dot ratchet wheel is scratched “L” on the underside and the two-dot ratchet wheel is scratched “R” on its underside. Both dustpipes are scratched “3194” under the foot. Escapement, balance, spring and jewelling The escapement as a whole is mounted on the ‘Navette’-shaped escapement platform. The platform is stamped “37” by the balance cock screw, on the underside (distance between pin centres: 53.4mm). The platform of the escapement is fixed with three screws, one of which, when unscrewed, releases a spring detent into engagement with the fourth wheel preventing a ‘runaway’ should there still be power on the train. Breguet-type spring detent escapement with double-spring detent mounted, via a brass block with 2 screws, on a brass foot. The foot has a brass arm with a straight steel screw for banking the detent at the end. There is a plugged hole in the navette baseplate, under this foot. The escape wheel is loosely run on its pinion with a brass collet, the pinion and wheel connected, on top of the wheel, by a small, blued-steel helical spring with terminal curves on both ends, pinned to collets on arbor and wheel. The detent has a gold passing spring screwed to a block on the side of the detent blade, and which is angled in at about 5 degrees, banking at its end on an upstanding steel pin on the slightly curved-in nose of detent horn. A highly polished-steel locking ‘stone’ is shellacked into the detent pipe. The impulse roller has a steeply raked, pale pink impulse jewel with cut out opposite for poising, and the discharge roller has a pink stone inset. There is a balance lock/unlock control on the dial which connects to a brass sprung blade, mounted on a brass column by the balance, and having a notched, curved block on the end. This engages with an upstanding pin on the end of one of the balance arms when the control is activated, the pin on the balance entering the notch in the blade. The undersprung, two-arm ‘platina’ bimetal balance has very slightly tapered steel arms (now with blue lacquer) and the rims are now fixed to the arms with steel ‘L’ brackets, the single meantime nut screw doubling as the fixing screw, alongside a steady pin. There are brass meantime nuts mounted on the threads at the end of the arms and at 90° on the rims. There are also additional small, white metal (probably platinum) meantime nuts mounted on the rims just to one side of the balance arms, and smaller brass compensation screws to the compensation nuts at 90° (holes present for a choice of eleven positions). There is a shaped, blued-steel arm with a small threaded hole at its outer end, fixed at the centre of the balance and pointing in the direction of the stud. Its function is unknown, but may have been an alternative locking arm for the balance securing device. The grey-finished steel helical balance spring has no terminals but is thinned towards the centre and is of the ‘barreling’ type, where only the middle coils breathe during running. The stud, which has the spring clamped to it, is clamped to an adjustable brass stud-block which has a central screw and three positioning screws to aid slight isochronal adjustments and to position the lower termination of the balance spring correctly. The upper jewelling of the balance pivot consists of a large clear hole shellacked into the steel setting with a facetted diamond endstone in a steel setting, all fixed on the balance cock in a steel ‘parachute’ shock-protection device. The other jewelling, which is mounted in brass settings (escape endstones in steel coquerette settings), extends to the balance and escape wheel with endstones and the escapement parts as mentioned, all stones a light pink. The centre third and fourth wheels have steel coquerette endplates on the ‘rear’ (lower when in use) pivots. Alterations/condition The brass box key is a later replacement. box fixing screw return springs were taken out and turned over, as both left and right springs had been refitted at some stage to push the screws down and out of the base. All else left as found. The base has two screws broken off. The lower part of the thread of the boxwood key socket was broken (now re-glued together) and the upstanding moulding on the lower half on the front left of the box and a small portion on the right hand side were broken off, now re-glued. The original flat brass securing arms and their screws for securing the bowl are now missing. The sight ring of the bezel was probably silvered later, when in England. The movement is in generally sound condition with some light spotting to the brasswork but virtually no signs of wear from use, the pivots in fine polished condition and the pinions unmarked. The winding key is a later replacement. The mainspring in one-dot barrel has been re-hooked at its outer end. The original ‘in-compression’ two-dot ratchet spring has been replaced with an ‘in-tension’ spring on the other side of the ratchet wheel at some stage in the movement’s life. The steel endplate for the third wheel on the main plate has a fracture running round the outside of the upper surface and across one of the screw holes. There is evidence the fourth wheel has been remounted on its pinion (perhaps after repivoting?). The minute wheel has evidently been lost at some stage and has been replaced with a poorly cut brass replacement with what appears to be an aluminium pinion. The balance appears to have had a new, finely made staff (without the usual ‘Breguet type’ notch for staff clamping during adjustment of the rollers) and seems to have had work on the steel arms, the ‘L’ brackets securing the rim segments being a later alteration, then ‘blued’ with the bluing lacquer to disguise the changes. The pin for the upper balance jewelling has probably been altered, the upper hole being reset in shellac and the diamond endstone probably an English replacement. The balance lock device is now disposed to lock the balance at the extent of its swing, enabling the device to be used as a ‘stop/start’ device and not, as Breguet intended, as a device to lock the balance at the position of rest. Dial letters… Commentary, Provenance, etc xxxxxxx Main Plate: 97.4 Barrels: Left (next to scape cock and all parts marked with one spot) Inside barrel: 38.6 brace in barrel at 90° from hook Arbor: 11.25 brass, with brass hook, not snailed Thickness: 0.20 – 0.23 Height: 22.3 Spring Signature: “Vincent Jv 1820” and “No. 3194” [9 overwrites 4]. Set up: 4 turns (total output: 12 ½ turns) Right (next to balance cock and all parts marked with two spots) Inside barrel: 38.7 brace in barrel at 90° from hook Arbor: 11.3 brass, with brass hook, not snailed. Thickness: 0.20 – 0.22 (21 turns unwound in barrel) Height: 22.2 Spring Signature: “Vincent Jv 1820”, “No 3194” and “3194”, on outside of spring near end. Set-up: 4 turns (total output 13 turns) TRAIN COUNT Wheel / Pinion (+ext dia) Comment: Crossings? Marks?Jewelled? Great (one-dot): 120 / 44.1 Ratchet: 24 / 13.9 Brass Stopwork driver: 10 / 15.3 Brass with steel finger Stopwork driven: 8 / 11.8 Brass `with steel stop-piece 3 ¾ turns of barrel produced Great (two-dot): 120 / 44.0 Ratchet: 24 / 13.9 Brass Stopwork driver: 10 / 15.4 Brass with steel finger Stopwork driven: 8 / 11.8 Brass `with steel stop-piece 3 ¾ turns of barrel produced Centre/2nd: 96 / 35.6 + 9 / appr. 4.0 4 curved crossings. flat polished finish Pinion very finely finished Third: 90 / 33.5 + 12 / 4.6 “ Fourth: 80 / 26.75 + 12 / 4.50 “ Escape: 18 / 19.9 + 12 / 4.2 “ Balance Frequency: 14,400 vbs/ hr (half seconds) Hour: 48 / 16.1 Minute Wheel: 42 / 15.3 Minute Pinion: 12 / 4.4 (Aluminium) Cannon: 14 / 5.5 (Polished steel, wheel blued) Impulse pallet tip Ø: 6.9 Discharge pallet tip radius: 1.5 Balance Ø: 35.8 Balance Mass (incl. b/spring & stud): 6.0g Balance spring Ø: 12.1 Material: Lightly polished steel Turns: 9 ¾ (anti c/w down)
Date made

Artist/Maker Breguet
Credit National Maritime Museum, Greenwich, London
Materials brass; steel; mahogany
Measurements Overall: 174 x 230 x 195 mm
Parts
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