- Museum number
CENTRE-SECONDS POCKET-CHRONOMETER MOVEMENT WITH ROBIN TYPE LEVER ESCAPEMENT.
Centre-seconds chronometer watch.
Lever chronometer escapement.
- Production date
Diameter: 43 millimetres (back-plate)
Diameter: 46.40 millimetres (dial)
Thickness: 10.30 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by R. Thompson, c. 1860.(1)
Watch Movement with Robin-Type Escapement
Signature: On the back plate 'R. Thompson, NEWCASTLE on Tyne London Patent Chronometer 2082'.
Dial and hands: Flat enamel dial with separate sunk central portion, signed 'Chronometer 2082' in the upper half, see Drake registration no. 1858,1201.1828 159 for a very similar dial and hands. The dial attached directly to the front plate by three feet and pins, and marked on the reverse B.
Gold minute and hour hands, blued steel sweep centre seconds hand.
Ebauche marks 18, 2, H.F., 2082 (see registration no. 1858,1201.1828 159). Also under the balance cock 2082 HF. Front plate diam. 46.2 mm; back plate diam. 43.2 mm; frame h. 7.9 mm.
Frame: Three-quarter plate construction with three turned pillars, the back plate retained by recessed blued steel screws. The construction similar to registration no. 1958,1201.1828 but laid out for a non-reversed fusee and the fourth arbor planted at the centre. The movement fixed in its case by a hinge at 12 o'clock, and a peg opposite fixed in the edge of the front plate. All the brass parts gilded.
Fusee: Keywind fusee, with the usual stop-work and maintaining power with a steel maintaining ratchet wheel. The setting-up-work fitted in a shallow recess on the dial side of the front plate, the barrel arbor with an extended square on that end only.
Going-train: The offset centre arbor hollow, for the squared hand-set arbor carrying a wheel meshing with the minute wheel to drive the motion work. The fourth arbor planted at the centre and carrying the sweep centre seconds hand on the lower extended pivot.
Jewelling: The lower pivot of the centre arbor and those of the fourth escape wheel and balance arbors in pierced jewels. Those of the escape wheel and balance with endstones. The pivots of the pallet frame are not in pierced jewels. The jewels for the fourth arbor pivots are bombé.
Escapement: A type of Robin escapement in which the teeth of the escape wheel are locked alternately on jewelled pallets in a steel pallet frame. The drops are alternately large and small, and during the large drop an escape tooth transmits impulse to a jewelled impulse roller on the balance staff. A steel lever on the underside of the pallet frame works in conjunction with a steel pin protruding from below the impulse roller to unlock the escapement. Fork and roller safety action is provided by the shaped edge of the notch and the balance staff itself, and with a slot filed behind the steel pin on the impulse roller, as in a modern pin-pallet lever escapement. The pallets have draw, so that when the escape wheel is locked the lever is held clear of the roller and banked on one or other banking pin. The brass escape wheel, burnished on both sides, not sunk out for lightness. The steel roller, pallet frame and fork polished.
Balance: Bimetallic two-armed balance with gold screws. Diam. 16.4 mm, h. 1.2 mm.
Balance spring: Blued steel spiral spring of 11¾ turns without an overcoil or terminal curve, pinned to a polished steel stud on the balance cock, and round brass collet. A polished steel index fitted on the balance cock.
Going train counts:
Great wheel (fusee) 72 teeth
Centre pinion 10 leaves, wheel 64 teeth, 5 arms
Third pinion 8 leaves, wheel 60 teeth, 5 arms
Fourth pinion 8 leaves, wheel 56 teeth, 5 arms
Escape pinion 7 leaves, wheel 15 teeth, 3 arms
Beats per hour: 14,400
Cannon wheel 36 teeth, minute pinion 6 leaves
Hour wheel 72 teeth, minute wheel 36 teeth Transmission wheel 36 teeth
Provenance: Ilbert Collection; purchased by Ilbert from Malcolm Gardner in 1932.
(1) Although this chronometer does not have a Patent Union Chronometer escapement, it is assumed to fit into the same series and therefore to predate those with higher serial numbers.
- Not on display
Latest: 4 (2017)
4 (Oct 1995) Balance pivot broken.
- Acquisition date
- Acquisition notes
- Following the successful acquisition of the celebrated Ilbert collection of clocks (1958,1006 collection), prints and other related materials made possible by the generous donation of funds by Gilbert Edgar CBE Ilbert's watches were then acquired using funds provided by Gilbert Edgar, public donations and government funds.
- Britain, Europe and Prehistory
- Registration number
- Additional IDs
Previous owner/ex-collection number: CAI.1832 (Ilbert Collection)
Previous owner/ex-collection number: M183 (Ilbert Ledger)