Marine chronometer numbered 349, by James Hatton. An eight-day double-frame movement with reverse fusee. The fusee has stop-work and Harrison's maintaining power. Earnshaw-type spring-detent escapement. Compensation balance with helical balance spring.

Mounted in two-tier box, push-catch for lid and lock for upper half. Lower half has a right-angle bracket fixed to the back limiting opening of upper half to 90 degrees. The box has surface-mounted handles on the sides, brass gimbals and a non-ratcheting winding key. The gimbal lock is, however, non-standard The box lock is surrounded by a shaped brass insert. The top of the lid has a brass plaque inset marked 'Swallow'. The inside of the upper and lower halves is covered with green baize. The sliding cover to the winding hole, on the base of the brass canister, is inscribed, 'Wind up to the left hand once a week'. The glass and bezel is push-fit, not screw-on. The canister has an offset weight fitted inside to balance the movement.

Silvered brass dial with Roman hour-numerals and Arabic 5-minute numerals and a large seconds dial having Arabic ten-second figures. The dial is inscribed in the centre 'JA's Hatton London 349'. There is an up-and-down indicator below the XII position, marked from Up on the left through the figures 1-7 and then Down on the right. The chronometer is in fair condition.

This chronometer was used on board Swallow, a merchant ship working the trade route between India and England in the early 19th century. East India Company captains were the first to use chronometers on a regular basis. The Royal Navy was slower to accept the new device but, by the late 1820s, most large ships carried at least one chronometer.


NMM CHRONOMETER CATALOGUE DATA ENTRY

MIMSY NO: ZAA0178

James Hatton, London c.1810 No.349

8 day marine chronometer in mahogany box

Hatton….

Box/Mounting

Two-tier, plain mahogany box measuring 218mm high, 225mm wide, and 230mm deep. A hinged lid is inset into the upper half and opens, with a push-button on the front, to just over 90°, the opening assisted by two spring loaded pins pushing under the lid on either side. The lid, which is inlaid on top with a large rectangular brass plaque engraved: “Swallow”, opens to a glazed viewing panel, retained with narrow half-round wooden beading. The right hand lid hinge is marked: “M&M / PATENT”. The lock on the lower half is inlaid with a brass, ‘scalloped square’ escutcheon, and the upper half is limited in opening to 90° by an L bracket fixed to the back of the lower half, which supports the back of the upper half when open.

The box has brass drop handles on the sides, with the heads of brass screws evident for the gimbal mountings and locking device. The whole of the inside of the box is lined with coarse, dark green baize, that in the lower half running up over the top of the edge, forming a dust seal with the upper half when closed. The gimbals are pivoted in the corners at the rear left and front right, the locking arm, which swings over and embraces the full height of the gimbal ring, bing positioned at the rear right in the box. A brass clip, mounted inside the upper half on the right, engages with the gimbal locking piece if the gimbals are unlocked, preventing the lock from engaging during use. The friction fitting, brass, moulded, vertical sided bezel is fixed with side screws at III and IX and has a high convex glass over the dial. On the underside it is scratched: “349” “XII” and “ΔVI”. The straight sided, seamed, bowl, has a flat base inset, fixed with two radial screws, and with a small sprung dust shutter, engraved: “Wind up to the Left hand Once A Week”. The bowl has is scratched inside “ΔVI” and has a crescent-shaped brass counterweight fixed at VI o’clock in the base. There are three plugged holes in the wall of the bowl, beneath the position of both present gimbal mounts. The underside of the box has no covering. The brass, ‘inverted heart’ winding key is of the type associated with James Hatton and may well be the original key.

Dial and hands

The 117.8 mm Ø, engraved and wax-filled, silvered-brass dial is inset into the brass edge, secured with four small screws on the front of the dial. The upper surface of the brass edge, under the dial, is scratched “ΔVI”. The brass edge has three feet, silver soldered to the underside, and which fix the edge to the pillar plate with brass latches (marked with 1, 2 and 3 dots for locations). The dial has roman hour numerals and Arabic five minute figures. There is a large seconds dial at IV o’clock having Arabic ten-second figures with straight batons at alternate five-second intervals and is marked: “349” below 60. The dial is signed across the centre: “JAS. HATTON LONDON”. Below XII is an up and down sector, marked in arabic numerals for the seven days from 1 (alongside “Up”) to 7 (alongside “Down”). Blued steel open-triangle and poker-hands with a fine, blued steel pointer seconds hand without tail, and a blued steel pointer for the up and down dial.

Movement

Double-frame fusee movement, the main frame with three pillars with flanges at either end and double fins at the lower ends and a single fin towards the upper ends. Pillars fixed with polished steel screws, with brass washers, at both ends. The general level of finish of the movement is good, with all brass frame parts polished and lightly curled. The barrel is mounted under a large cock off the main frame, and has Hatton’s characteristic six radial slots in the cap for observation and re-lubrication of the mainspring. The sub frame runs the third and fourth wheels and the escapement, and has three square-section pillars with rectangular feet at either end, each end fixed with two screws from the inside (holes in the upper plate to access lower screws with a long screwdriver). A steel pallet screwed to the lower fusee pivot advances a 19 tooth circular rack, the teeth acting with a spring jumper to actuate an up and down hands on the dial, advancing in 12 hour jumps.

The later signed blued steel mainspring has a round hooking with a steel hook in the barrel wall. There is a four-wheel train and a great wheel, the reverse fusee with Harrison’s maintaining power. The train wheels, which are possibly all rounded-up by hand, are brass with the third run on a cock on the pillar plate and the escape wheel run on a potence within the sub-frame and under a cock on its upper surface. The centre wheel holes have been plugged and re-pitched from new, and the other wheels (fusee, third, fourth and maintaining detent) are run in removable bushes, probably in hardened brass. The pivots for the escape/centre/third/fourth have all been turned with a backslope, a la balance staff, to improve oil retention. The fourth wheel has a brass end plate on the upper end, and the escape wheel runs in simple, pink jeweled holes. Care has been taken to ensure all pitchings can be easily viewed.

Escapement, balance, spring and jewelling

Earnshaw-type spring detent escapement with grey (fine filed) finished foot detent screwed to the sub plate, alongside a steel screw-head banking piece. The detent has a gold passing spring running alongside the detent blade, and with a clear jewelled locking stone. The impulse roller has a raked, pink stone and the discharge roller also has a pink stone inset.

Plain, Hatton-type compensation balance has the usual 100° bimetal rim segments with small brass block-shaped compensation weights fixed to the rims with a screw von top and with a steel screw tangentially mounted in each weight for poising. The narrow steel arms of the balance end in small steel mean time screws, with small brass threads in holes in an extension to the rim the other side to the main rims segments. The blued steel helical balance spring has terminals on both ends, the upper terminal with a steel pointer stud fixed to the cock. A tiny hole alongside the stud, now redundant, probably originally conrtained a cam-device for fine adjustment of the stud for isochronism.The jewelling, which is all in pink stones mounted in brass settings (upper balance has a faceted diamond endstone in a blued steel setting), extends only to the balance and escape wheel (only the balance with endstones) and the escapement parts as mentioned.

Alterations/condition

The wooden box is in sound and reasonably clean condition with a number of small knocks and dents. The drop handles and outer brasswork are reasonably clean and sound, and the inner brasswork is well preserved. The green baize inside the case is coming detached in places and is partially missing on the box edge at the rear left. The two screws to secure the movement in the bowl and the two for securing the bezel to the bowl are all now missing.

The dial silvering is very clean, with a thick coat of lacquer.

The movement is in generally sound clean condition, though it was found to be thick with old, solidified oil and the edges of the plates are somewhat fingerprinted. There are burrs raised under the cock foot suggesting the balance has had a new staff or has had it repivoted. The movement has only been very lightly cleaned, and has been re-oiled, during inspection. The up and down segment has one tooth repaired with a brass pin inserted diagonally and shaped accordingly

Commentary, Provenance, etc

The gimbals almost certainly originally included Hatton’s sprung suspension connecting the gimbal ring to the bowl with a full circular nickel band.

London frame?

Movement data

Pillar Plate Ø: 123.4

Plate distance (main frame): 40.9

Inside barrel Ø: 50.4

Arbor Ø: 14.9 brass, unsnailed.

Thickness: 0.44 – 0.36

Height: 32.0

(7 ½ turns output from barrel)

Set up: (7 as found) 8 teeth, to line up click with spot on wheel

Signature: “Geo. Cotton July 1879 / 14 Percival St / Clerkenwell London” (scratched on inside of spring, 30cms from end)


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

Fusee/Great: 144 / 58.5 No.of Turns:16 (Chain 150.0cms, 283 links)


Ratchet: 40 / 25.1 Brass, 2 steel clicks

Maintaining Power: 120 / 55.5 Brass

Centre/2nd: 90 / 36.6 + 12 / 5.5 6 tapered crossings, all flat finished. Polished pinion

Third: 80 / 30.5 + 12 / 5.3 “

Fourth: 80 / 26.2 + 10 / 4.2 “

Escape: 12 / 13.0 + 8 / 3.0 3 curved crossings

Hour: 60 / 25.8 Brass, solid

Minute Wheel: 64 / 27.3 “ 6 tapered crossings

Minute Pinion: 20 / 9.0 Highly polished steel

Cannon: 16 / 7.5 Polished steel

Up and down wheel: 19 (of 30) / 52.8 11 teeth of rim plain, uncut

Set up ratchet: 20 / appr.25.7 Brass, dot-marked for click position

Impulse pallet tip Ø: 5.7

Discharge pallet tip radius: 1.6

Detent length: 26.0

Ø of balance: 31.9 Balance Mass (incl. b/spring & stud): 4.8g

Balance spring Ø: 15.3 Material: blued steel

Turns incl. terminals: 6 ¾ (a-c/w down)