- 672
Thomas Mudge, A historically important and early marine timekeeper with constant force escapement, 'Mudge Green', started in 1776 and completed in 1779
Description
- Thomas Mudge
- dial plate 102mm, case diameter 115mm, case height 65mm
Gilt full plate movement signed Tho Mudge 1777, baluster pillars with squared bases on the dial side, dust exclusion pipe for the winding square, fine foliate and griffin motif pierced and engraved balance bridge, recessed dial plate screwed to bottom plate, held in the case by two dog screws in dial plate.
Train
Reverse 7-turn fusee with Harrison’s maintaining power, fixed barrel with ratchet set up, over-hung outer piece for chain and rotation, fine polished wheels with 6 arm crossings, great wheel with 100 teeth, centre wheel with 120 teeth and 20 leaves on the pinion, third wheel with 120 teeth and 16 leaves on the pinion, contrate wheel with 120 teeth and 15 leaves on the pinion, also with a wheel for the seconds of 45 teeth driving a reversing wheel of the same count, escape wheel with a pinion of 12 leaves and 15 escape wheel teeth.
Escapement
Constant force escapement developed by Thomas Mudge from the drawings by Johan Jakob Huber, 15 tooth escape wheel with no lift, polished steel arbors and pivots, hard stone pallets shaped for lift and locking, both pallets with constant force blued spiral springs, all running in jewels with endstones, held in adjustable potance.
Balance
Polished brass flat rim balance with fine three arm crossing and counterpoise weight, cranked balance staff with pins for impulse, two matched blued steel spiral balance springs, the balance pivots run between roller wheels to minimize friction which are held by pillared plates, diamond endstone for the balance bridge and ruby endstone for the balance potance.
Temperature compensation
Separate and distinct mechanism mounted on the back plate comprising of two straight bi-metallic springs acting on a lever, the lever is pivoted and at the other end has two curb pins that act on the outer end of the bottom balance spring, the other end is formed into a long cranked tail protruding from under the balance guard whose end is visible by the signature in the back plate, fine adjustments are obtained by the sliding movement of the bi-metallic springs through adjustment screws mounted either side of the balance guard.
Regulation
Obtained by curb pins acting on the top balance spring, the adjustment is through a square mounted on the balance bridge with a sliding brass assembly held in tension by a swan neck spring and indexed on a semi-circular plate and indicated by a blued steel pointer.
Dial
Gilt dial plate screwed to movement bottom plate, eccentric enamel mean time and subsidiary seconds dials with gilt stepped bezels, arabic numerals, applied fine silver cast and chased mounts of flora and fauna with heads of griffins.
Hands
Blued steel ringed poker form counterpoised hands.
Case
Brass drum-form case, gilt stepped bezels, band covered with green Shagreen, base with winding hole and shutter, hinged top with convex glass.
Provenance
Christie's Geneva, November 8, 1976, lot 240
Time Museum Inventory No. 1303
Exhibited
An Exhibition of English Pocket Chronometers from the 18th to the 20th Century. Bobinet, London, December 1st-11th, 1976
Literature
Britten, F.J. Old Clocks, Watches and Their Makers. London, Ninth Edition, 1982, pp. 128a-b, 192-193
Chamberlain, Paul. It’s About Time. London, 1978, pp. 337-339
Daniels, George. "Thomas Mudge: The Complete Horologist." Antiquarian Horology, no. 13. (1981), pp. 150-173
Garver, Thomas H. "Keeping Time." The Time Museum Brochure, reprinted from Invention & Technology. (Fall 1992), p. 11
Good, R., F.B.H.I. "The Mudge Marine Timekeeper," included in Pioneers of Precision Timekeeping. Sussex, (Monograph No. 3), pp. 75-91
Gould, R.T. The Marine Chronometer, Its History and Devlopment. London, 1923, reprinted 1989, pp. 107-125
Hutchinson, Beresford. "Some Oberservations on the Timekeepers of Thomas Mudge." Antiquarian Horology, no. 11. (Spring 1978), pp. 715-719
Mudge Jr., Thomas. A Description with Plates of the Timekeeper Invented by the Late Thomas Mudge. London, 1799 (reprinted London 1977.)
Penney, David. "Thomas Mudge and the Longitude: A Reason to Excel", included in Quest for Longitude, edited by William J.H. Andrewes. Cambridge Massachusetts, 1993, pp. 294-308, pl. 18
Randall, Anthony G. and Good, Richard. Catalogue of Watches in the British Museum, VI Pocket Chronometers, Marine Chronometers, and other Portable Precision Timekeepers. London, 1990, pp. 181-185
Rees, A. Clocks, Watches and Chronometers, Extracts. London, reprinted 1970
Randall, cat. no. 118