Breguet, Paris, c.1827 No.4138

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 224mm high, 260mm wide, and 233mm deep. The top of the box has an inset lid with side-pin hinges and an inset strut with pivoting anchorage points in top and lid, allowing it to open to just over 90°. The lid is inlaid with a brass, diamond-shaped plaque, engraved: “No.4138”, and opens to a circular glazed panel retained with narrow knurled 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 originally with a brass spring inside the upper half to ‘jump’ the lid open when the button is pressed. The lock on the lower half has an oval, brass escutcheon. The box has a full-width, ‘butt’-type, ‘piano’ hinge and a brass strut on the left hand side, restraining the upper half to 90°opening (now worn and the butt hinge takes the strain). 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 type, with brass drop handles on the sides and lacquered brass gimbals with a narrow, straight-sided bezel retained with two side screws and having a beveled flat glass over the dial. The centre body of the movement-housing doubles as the brass edge of the movement and has a knurled beading running round the outside. Both bezel and bowl are fixed to it with a pair of screws. The thick, ‘rounded rectangle’ gimbal ring has a deeply bevelled upper surface, and a pivoting cradle (pivoted in the rear corners inside the box) can be swung up from below to embrace the underside of the bowl and lock the assembly firmly. The cradle is actuated by a lever on a vertical arbor at the rear-right of the box which swings a steeply angled brass ramp at its base under the cradle to raise it up. When this lever is in the locked position and the box is closed, a cast brass pointed peg, mounted in the upper half, comes down alongside the lever and prevents it from working loose. A vertically mounted brass blade, terminating in a ‘T’ shaped block at the upper end, is positioned under the gimbals by the left hand pivot. It appears to have been intended as a damping piece to prevent excessive swinging of the gimbals. 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:”4138” and the recess on the underside is scratched: “hd / 20 12 12 / 27 8 23 / 2 8 27 / 13 5 29” , “609 FG” , “GIL-14” , “8964”, “1242”, “6410”, “9-99 W”, “9.12.03 AGW”, “20.8.08 AGW”. The later brass winding key, which is stamped: “6”, is stowed in a typical Breguet-type boxwood socket in the rear left of the box, and has a mahogany retaining block fixed up inside the upper half which secures the key in place when the box is closed. In the right and left sides of the lower half of the box there are vertical holes going through to the base, containing sprung-loaded 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. As well as the original-type steel key for the box, there is a spare brass key associated with the chronometer. The brass winding key is stamped “6” and another spare brass key, also associated, is stamped “12”.

Dial and hands

The 128 mm Ø, engraved and wax-filled, French-silvered matt-finish dial is attached to the brass edge on the front with one screw at the top of the seconds dial. The movement is attached to the brass edge with four dot-marked steel screws from the inside. 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 - No.4138”. On the right of the dial is a segmental Up & Down dial marked:”DEVELOP’T DU RESSORT”. The back of the dial has been ‘knocked out’ in a semi-circle at the top of the dial, almost certainly where: “DEPOT DE LA MARINE” or something to that effect, would have been engraved. There is also ‘knocking out’ immediately after “Breguet” on the dial, almost certainly where “et Fils” would have been engraved. Blued steel spade and poker hands with a fine, blued steel pointer seconds hand with a counter-poised tail and a poker up & down hand.

Movement

Double-frame fusee movement the main frame having three plain straight pillars and encompassing the centre and third wheels. The escapement is mounted on a separate platform, standing on three brass pillars, with the fourth wheel run on a cock and potence under the platform. The general level of finish of the movement is high with most movement parts flat-polished.

The upper surface of the main upper plate is stamped: “4138”. The fusee has Harrison’s maintaining power with the steel m/p wheel run in a large steel bearing within the great wheel. There are double steel clicks and a finely cut steel ratchet wheel mounted in a heavy brass boss, fixed into the fusee. Continental type stopwork, with a steel block on the plate and a sliding steel bar, actuated by the last turn of the fusee chain, mounted in the top of the fusee. There are five plugged holes here which suggest earlier attempts to fit stopwork, the design of which was subsequently changed. The fusee pipe has a dust trap on the square fitted under it. A blued steel finger, pinned on a square on the end of the lower fusee pivot, advances a segmental rack with jumper spring, which has the up and down hand attached.

The wheels are all brass with the fourth wheel run between cocks on either side of \the pillar plate, the upper pivot having a steel coquerette endpiece. There is a meshing inspection hole by the 2nd/3rd pivot in the upper plate, and inspection holes for great/centre and 4th / escape in the pillar plate..

Escapement, balance, spring and jewelling

The platform of the escapement is fixed with three screws, one of which has a long head to protect the balance when the movement is out of the bowl, and one which, when unscrewed, releases a spring detent into engagement with the fourth wheel preventing a ‘runaway’ should there still be power on the train.

The escapement as a whole is mounted on the ‘Navette’-shaped escapement platform. The platform is scratched “4138” on its underside and there are three plugged holes in, and on the edge of, the sink for the lower balance pivot indicating an original centre for the balance and its endstone arrangement (further away from the escape), altered before completion. Breguet-type spring detent escapement with spring detent mounted, via a brass block with 2 screws, on a brass cock. The cock has a cam banking piece on its end, to adjust the depth of the detent locking with a brass screw. The detent has a screwed-on, gold passing spring running alongside the detent blade, and with a red locking stone. The undersprung, two-arm bimetal balance has straight blued-steel arms and the bimetal rims are of Breguet’s platina allow and steel. There are brass meantime nuts mounted on fixed threads at the end of the arms and 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 similar compensation screws adjacent to the meantime screws at 90°. The impulse roller has a steeply raked, pale pink impulse jewel and the discharge roller has a clear stone inset. The blued steel helical balance spring has no terminals but is tapered towards the centre and is of the ‘barreling’ type, where only the middle coils breathe during running. 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 upper jewelling of the balance pivot consists of a clear hole in a steel setting with a clear endstone in a steel setting, all fixed on the balance cock in a steel ‘parachute’ shock-protection device. The escape wheel jewel holes have brass settings with endstones in steel coquerettes.

Alterations/condition

The corner of the top of the box, supporting the right hand hinge of the lid, had come loose (dried glue) and was re-glued using HMG B72. There are two chips of veneer out of the corner pieces on the top which support the lid hinges. The push-button spring for the lid is missing. The steel finger to advance the up & down rack is split and has a separate finger soldered to it. A number of teeth on the maintaining power wheel are chipped.

The brasswork of the box is generally sound and crisp; the lacquer is slightly breaking down in places, but is generally sound. The surface finish of the box is generally sound with some slight old knocks and marking but with a generally high deep polish. There is one scratch on the lid running from the brass insert to the back left. The wooden structure round the right hinge pin on the lid was unglued and loose. This has been re-glued and is now sound. The external strut on the left hand side of the box has been strained beyond its limits and the upper half now stops partly by the strut and partly owing to the butt hinge.

The silvering of the dial is intact and generally sound, though there is some blackening round the edge of the dial and a fingerprint on the seconds dial at ‘35’.

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. Some 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.

Commentary, Provenance, etc


Pillar Plate Ø: 125.8
Upper plate Ø (semi-circular): 122.3

Barrel:

Inside barrel Ø: 51.0 brace in barrel at 90° from hook

Arbor Ø: 16.2 brass, with brass hook, not snailed.

Thickness: 0.4 not significantly tapered

Height: 32.6

Spring Signature: “Vincent Avril 1827” & “No 4138”.

Set-up ratchet: 28 / 19.9 (set-up 15 teeth, as found)


TRAIN COUNT


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

Great: 144 / 53.5 Round-bottom teeth
Ratchet: 50 / 27.0 Steel
Maintaining power: 150 / 49.1 Steel with steel bearing

Centre: 120 / 49.4 + 12 / 4.4 5 curved crossings. flat polished finish
Pinion nicely finished

Third: 90 / 44.0 + 15 / appr. 6.7 “

Fourth: 80 / 27.6 + 12 / 6.0 “ & pinion with round bottom leaves secured on collet with 2 screws

Escape: 15 / 19.0 + 10 / 3.6 4 curved crossings. flat polished finish
Pinion nicely finished
secured on collet with 2 screws

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

Hour: 48 / 14.2

Minute Wheel: 42 / 13.0

Minute Pinion: 12 / 3.65 Brass

Cannon: 14 / 5.1 Polished steel

Up & Down rack: 24 / @ 21.0 radius

Impulse pallet tip Ø: 7.65

Discharge pallet tip radius: 1.6

Balance Ø: 36.4 Balance Mass (incl. b/spring & stud): 6.3g

Balance spring Ø: 12.1 Material: Blued steel

Turns: 10 ¼ (anti c/w down)