Breguet, Paris, c.1827 No.4832

8 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 197mm high, 240mm wide, and 208mm deep. The top of the box has an inset, dovetailed mahogany removable slide, with a recess at the front for gripping with the finger. The slide can thus be drawn forward and taken off, revealing an open, 98mmØ aperture, through which the dial can be viewed. The slide has in the centre of the top, a diamond-shaped recess, probably originally for a brass plaque, engraved: “No.4832”. The lock on the lower half, is of the French, double-throw type, with two bolts engaging with two pins, and has an oval, brass escutcheon on the front. The box has a pair of plain hinges and a brass strut on the left 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 construction of the box is of the ‘lapped-mitre’ type, with the junction of the corners appearing on the sides of the box.

The box fittings are similar to the standard type, with brass drop handles on the sides and brass gimbals with a narrow, straight-sided screwed bezel (2 ¾ turns) with reeded moulding and having a flat, beveled glass over the dial with a concave brass sight ring. The underside of the bezel is scratched: “4832”. The thick, ‘rounded rectangle’, oval-section gimbal ring is without any form of locking, and the outer gimbal pivots are steel screws screwed straight into the wooden side of the lower half of the box.

The heavy brass bowl has an upstanding beading on the base, within which is the single winding hole, marked with an arrow to show direction of winding and covered by a swinging shutter to prevent the ingress of dust. The inside of the bowl is scratched:”4832” and has a lead weight fixed on one side, to counterbalance the spring barrel when the movement is in place.

The later, English-style, double ended brass winding key (for winding and hand-setting) is stowed in a hole in a simple corner shelf in the rear right of the box.

Dial and hands

The 113.6 mm Ø, engraved and wax-filled, French-silvered matt-finish dial is attached to the pillar plate of the movement with three feet, pinned to the plate, and the movement as a whole seats in the bowl on the edge of the dial, located with a side-pin at XII o’clock. The subsidiary hours and minutes dial has roman hour numerals 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 - No.4832”. The back of the dial is scratched: “4832” three times, one partially over another, and: “Marseille / aux chronometers / serti quatres rubis / Le 29 Janvier / 1854”. Polished and blued steel spade hands with a fine, blued steel pointer seconds hand with a solid counter-poised tail.

Movement

Full-plate, going barrel movement with four plain straight pillars pinned to the rear plate. The escapement is mounted on a separate platform, standing on the rear plate. A brass post stands next to the platform, protecting the balance from accidental damage should the movement be placed movement-down on the table. The wheels are all brass, the third wheel and fourth wheel are run on cocks on the front of the pillar plate and the second (‘centre’) wheel and third wheel are under a double cock on the rear plate. There is a steel endplate under the fourth wheel pivot on the rear plate. The general level of finish of the movement is high with most movement parts flat-polished.

The upper surface of the rear plate is stamped: “4832” and it has the inventory number: “36-601” painted on. The going barrel has a single click and a finely cut brass ratchet wheel. Continental type stopwork on the barrel cap, with a steel friction spring wrapping round the side of the stop wheel. The underside of the foot of the winding square pipe is scratched: “4832”. The underside of the ratchet wheel is stamped with one dot and a pair of dots. The barrel cap has “5” scratched on it.

There is a meshing inspection hole by the great / 2nd pivot in the pillar plate, and for the 2nd / 3rd in the rear double cock. All the pivot holes have been re-planted during construction

Escapement, balance, spring and jewelling

The ‘Navette’-shaped platform of the escapement is fixed with three screws and located with two steel steady-pins (51.65mm centre-distance). One of the fixing screws, when unscrewed, is intended to release a spring detent into engagement with the fourth wheel preventing a ‘runaway’ should there still be power on the train (spring detent and its screw now missing).

The platform is stamped on its upper surface: “188”, and is scratched “C.Gronlier / Havane 1855” and “R G 3.1970”on its underside. The underside of the platform is recessed with a sink to allow room for the steel endplate for the fourth wheel. Breguet-type spring detent escapement, but with replacement spring detent with a foot and single spring blade, mounted on the original brass mounting block, but the detent having a single fixing screw with brass pins on either side. The brass mounting block has a cam banking piece on its end, to adjust the depth of the detent locking with a brass screw. There is a screwed-on, gold passing spring running alongside the detent blade, and with a pale blue locking stone.

The undersprung, two-arm bimetal balance has straight blued-steel arms and the bimetal rims are of Breguet’s platina alloy and steel. There are brass meantime nuts mounted on fixed threads at the end of the arms and similar compensation nuts at 90° on the rims. There are also additional brass meantime nuts mounted on the rims just to one side of the balance arms, and a series of 9 holes at the ends of the rim segments (and one before the compensation weights), for similar compensation screws. The impulse roller has a steeply raked, polished steel impulse jewel with a poising hole opposite, and the discharge roller has a clear stone inset. The blued steel helical balance spring has no terminals. Observation suggests this spring is not of the ‘barreling’ type, where only the middle coils breathe during running, but it is probably tapered towards the centre as it appears to breathe concentrically. The Breguet-type staff has the two ‘clamping notches’ for holding during roller adjustment/removal. The stud is clamped to a 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 collet at the inner terminal has one platinum poising weight opposite the spring clamp.

The rear jewelling of the balance pivot consists of a clear hole in a brass setting in the cock, with a faceted diamond endstone in a steel coquerette, while the front jewelling is a clear hole in a brass setting with a steel endplate fixed over. The escape wheel jewel holes are both pink stones in brass settings, the rear having a pink endstone in a steel coquerette, the front having a simple steel endpiece.

Alterations/condition

The surface finish of the box is generally rather rubbed, knocked and stained. The corner of the slide on the top of the box has lost part of its veneer at the front right, and the inlaid tablet is missing. There has been some woodworm activity in the past but this now appears to be extinct. Otherwise the woodwork of the box is sound and stable. The brasswork of the box is generally sound, though now unlacquered and is quite heavily tarnished and patchy in finish. The bowl has many old fingerprints.

The silvering of the dial is intact and generally sound, though it has been quite heavily lacquered, which now gives `it quite a patchy appearance.

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. All beautifully ‘unscrubbed’. Some slight finger-printing round the edge of the upper plate. The movement was generally wiped clean and holes pegged, but the movement has not been fully cleaned.

There is a distinct pip mark on the rear steel balance endplate, probably where the chronometer movement ran dry when on display ‘upside down’ in the gallery during the 1970s. The lower balance staff pivot may have been repivoted, as the pivot is not Breguet’s slender conical type, and the diamond endstone is probably a later (English?) replacement.

Commentary, Provenance, etc

Very much like very posh clockwork now, rather than chronometer design

Pillar Plate Ø: 101.6
Upper (rear) plate Ø: 101.4

Barrel:

Inside barrel Ø: 43.9 side-pin to locate cap

Arbor Ø: 13.1 steel, not snailed.

Thickness: 0.30 – 0.25

Height: 21.2

Spring Signature: “Vincent 8bre 1829”, “4823” [sic] & “No 4832”.

Set-up: 5 turns (total output 10 turns)


TRAIN COUNT


Wheel / Pinion (+ext Ø) Comment: Crossings? Marks?Jewelled?

Great: 90 / 51.0

Ratchet: 48 / 20.8 Brass

Stopwork with three spaces over approx 135 degrees (3 ¾ turns of barrel produced)

Centre(2nd): 80 / 41.6 + 10 / 6.0 4 curved crossings. flat curled finish
Pinion very nicely finished

Third: 75 / 35.3 + 10 / 5.5 “

Fourth: 80 / 27.2 + 10 / 5.0 “

Escape: 18 / 18.7 + 12 / 4.1 4 curved crossings. flat polished finish
Pinion nicely finished
secured on collet with 2 screws

Balance Frequency: 14,400 vbs/ hr (half seconds)

Hour: 84 / 31.1

Minute Wheel: 48 / 17.25

Minute Pinion: 7 / app.3.1 Highly polished steel

Cannon: 48 / 17.25 Brass

Impulse pallet tip Ø: 6.85

Discharge pallet tip radius: 1.4

Balance Ø: 35.8 Balance Mass (incl. b/spring & stud): 5.8g

Balance spring Ø: 12.2 Material: Blued steel

Turns: 11 ¼ (c/w down)