- Museum number
SILVER CASED SUBSIDIARY SECONDS POCKET-CHRONOMETER MOVEMENT WITH SPRING DETENT ESCAPEMENT.
Full-plate; fusee; Harrison's maintaining power.
Arnold spring detent escapement; Earnshaw type bimetallic balance.
White enamel dial, hours I-XII, subsidiary seconds 10-60, signed.
Gold hour hand, replacement gold minute hand and replacement blued-steel
Silver case not original, French ca.1819 with maker's mark FV Wheel above, fleur-de-lis below, within a lozenge. Numbered B 4128 and 1984 B. Pendant with quality control mark.
- Production date
Diameter: 52.90 millimetres (case)
Diameter: 45.20 millimetres (dial)
Thickness: 19.60 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by John Roger Arnold, Probably 1811 (nos 3099 and 3605 are dated 1811)
Signature: On the barrel bridge 'Jn° R. Arnold London'. On the back plate 'No. 3580'.
Case: Not original. Silver engine-turned open face of French origin with the French quality control mark for 1819. Inside the dome the number 4128B and inside the back 1948 with the B beneath. Diam. 53.0 mm, overall h. 19.7 mm. [Case maker’s mark in a lozenge FV with wheel above and fleur de lys below.]
Dial and hands: Flat enamel dial with subsidiary seconds at 6 o'clock. The signature 'Arnold' in cursive script in the upper half.
Gold minute and hour hands, the minute not original, blued steel seconds hand also not original.
A new series from the preceding, and of poorer quality. Ebauche marks on the front plate under the dial 18, 9.
Dial plate diam. 54.8 mm; front plate diam. 43.2 mm; back plate diam. 40.7 mm; frame h. 7.3 mm.
Frame: Full plate with detachable barrel bridge, four turned pillars, the back plate retained by pins. The movement hinge riveted to the dial plate at 12 o'clock, the case catch opposite and attached with its spring to the dial side of the front plate. The original dust-excluding ring around the edge of the frame (now missing) was held by two eccentric-headed blued steel screws. No dust pipe round the winding square.
Fusee: Keywind fusee fitted with stop-work and maintaining power, brass maintaining ratchet wheel, the detent for this missing. The setting-up-work under the dial on the front plate.
Going train: Similar train to registration nos 1958,1201.1580-2 except that the escape wheel has sixteen teeth.
Jewelling: The fourth pivot on the dial side only in a pierced jewel. The pivots of the escapement in pierced jewels, with endstones, that in the balance cock a plain ruby endstone set in a blued steel ring. The discharge roller jewelled, the impulse roller plain steel.
Escapement: The remains of an Arnold detent escapement, the sixteen-teeth brass escape badly damaged, the detent broken and only the foot remaining.
Balance: Bimetallic balance of Earnshaw type with wide crossbar and brass segment weights secured by polished steel screws. Two small gold screws set in the rims near their fixed ends. The outer edges of the rims graduated with a series of vertical scratches. Diam. of rim 17.3 mm, h. 1.5 mm.
Balance spring: Blued steel flat spiral spring without terminal curve pinned to an overhanging blued steel stud screwed to the back plate by the winding square. A blued steel index fitted under the balance cock and with its tail passing over a graduated sector on the back plate.
Balance cock: Plain (i.e. no engraving or other decoration). The cock screw not original and the hole in the cock through which it passes mutilated.
Great wheel (fusee) 60 teeth
Centre pinion 12 leaves, wheel 64 teeth, no crossings
Third pinion 8 leaves, wheel 60 teeth, 4 arms
Fourth pinion 8 leaves, wheel 80 teeth, 4 arms
Escape pinion 8 leaves, wheel 16 teeth, 4 arms
Beats per hour: 19,200
Cannon pinion 12 leaves, minute pinion 16 leaves
Hour wheel 48 teeth, minute wheel 48 teeth.
Provenance: Ilbert Collection, purchased by Ilbert from Davidson in 1932.
- Not on display
Latest: 2 (2017)
4 (Oct 1995) Broken spring detent only foot remains.
- 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.1844 (Ilbert Collection)
Previous owner/ex-collection number: M48 (Ilbert Ledger)