- Museum number
POCKET-CHRONOMETER MOVEMENT WITH SPRING DETENT ESCAPEMENT.
Spring detent escapement; balance etc. missing.
- Production date
- 1812 - 1813
Diameter: 41.50 millimetres (back-plate)
Diameter: 47.20 millimetres (dial)
Thickness: 22.90 millimetres
- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by Thomas Earnshaw, 1805
Signature: On the back plate 'Thos Earnshaw Invt et Fecit 808 '. On the barrel bridge '3816'. On the dial, in the upper half below the figure XII 'THOMAS EARNSHAW INVT et fecit N° 808'.
Dial and hands: Enamel dial, the edge curved, similar to registration no. 1958,1201.1592 and 1958,1201.1593. The hands are missing.
Dial plate diam. 47.4 mm; front plate diam. 42.9 mm; back plate diam. 41.9 mm; frame h. 8.53 mm.
Frame: Similar to 1958,1201.1592. No movement hinge, case catch or spring has ever been fitted to the dial plate. The movement was secured in its case by a positioning peg and two screws through the case middle and into the dial plate radially.
Fusee: Similar to 1958,1201.1592, a brass dust-excluding cap is held on the winding square by a polished steel screw.
Jewelling: Only the pivots of the escapement in pierced jewels with endstones. The outer surface of the endstones curved.
Escapement: Only the brass escape wheel remaining, the leading edges of the teeth slightly damaged. Originally the escapement would have resembled that of 1958,1201.1592. The brass arm to which the detent was fixed is still in place, also the adjusting screw set in a slot in the edge of the back plate, and the detent banking.
Balance: Missing, it would probably have resembled that of 1958,1201.1592.
Balance spring: Probably pinned to a stud on the balance cock, both are missing. There is no indication that there was an index.
Great wheel (fusee) 60 teeth, worn
Centre pinion 12 leaves, wheel 64 teeth, no crossings
Third pinion 8 leaves, wheel 60 teeth, 4 arms
Fourth pinion 8 leaves, wheel 70 teeth, 4 arms
Escape pinion 7 leaves, wheel 15 teeth, 3 arms
Beats per hour: 18,000
Cannon pinion 12 leaves, brass minute pinion 14 leaves
Hour wheel 42 teeth, minute wheel 48 teeth.
Provenance: Ilbert Collection, purchased by Ilbert from Ash in 1932.
- Not on display
Latest: 3 (2017)
3 (Oct 1995) Balance and cock missing. Spring detent and hands missing.
- 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.1595 (Ilbert Collection)
Previous owner/ex-collection number: M136 (Ilbert Ledger)