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Important Modern & Vintage Timepieces

Geneva, May 15, 2016

LOT 132

THOMAS EARNSHAW QUARTER-REPEATING POCKET CHRONOMETER WITH Z BALANCE GOLD Thomas Earnshaw, Invt. Et Fecit, London, No. 3973. The cases with London hallmarks for 1819-20. Very fine and rare, 18k gold, pair-cased pocket Chronometer with "Z" balance.

OUTER two-body, by Richard Grove (mastermark RG), 1804, INNER two-body, "bassine", polished. White enamel with radial Roman numerals, outer minute track, large subsidiary seconds. Gold spade and leaf hands. 47 mm., frosted gilt full plate with cylindrical pillars, fusee and chain with Harrison's maintaining power, Earnshaw spring detent escapement, bimetallic "Z" balance with wedge-shaped sliding temperature weights and two gold meantime screws set with a special and unusual device in order to prevent a too important compensation for the high temperatures, single footed cock with diamond endstone, escapement jeweled, blued steel free-sprung helical balance spring with outer terminal curves.

CHF 5,000 - 7,000

HKD 40,000 - 56,000 / USD 5,200 - 7,300

Sold: CHF 10,125

Grading System
Case: 2-8

Very good

Slightly scratched

Movement: 2*

Very good

Overhaul recommended, at buyer's expense

Dial: 2-01

Very good

HANDS Original


Dial and movement signed. DIAM. 65 mm. THOMAS EARNSHAW (1749-1829) Born in Ashton-Under-Lyne in Lancashire, by 1780 he had the reputation of being a very fine watch finisher. He invented the modern Chronometer spring detent escapement towards the end of 1780, a design that he insisted was stolen by ARNOLD. However, it is likely that Earnshaw and Arnold arrived at their conclusions separately. Earnshaw perfected the fusing together of brass and steel to make laminae for compensation balances which previously had had to be riveted.