24,150 CHF
“Sugar-Tong Pocket Chronometer” Thomas Mc Cabe, Royal Exchange, London, No. 6183, movement by Thomas Earnshaw. Case by James Richards with London Hallmarks for 1807-8. Very fine and extremely rare, 18K yellow gold pocket chronometer with Earnshaw’s spring detent escapement and patent bimetallic “sugar-tong” compensation. Three-body, “bassine”, polished. White enamel with radial Roman numerals and outer minute divisions, subsidiary seconds. Gold “Breguet” hands. 42 mm., gilt brass full plate with ring-turned pillars, fusee and chain, Harrison’s maintaining power, Earnshaw’s spring detent escapement, escape wheel with endstones in screwed chaton, large polished steel flat-rim three-arm balance with diamond endstone, flat blued steel balance spring, chased and engraved single footed balance cock, Earnshaw’s bimetallic “sugar-tong” compensation coupled with the index regulator. Dial and movement signed. Diam. 55.5 mm. Notes The “Sugar-Tong” Compensation. Although Earnshaw made pocket watches with bimetallic balances and free-sprung helical springs, he equally often turned them out with an uncut flat steel balance, spiral spring, regulator and compensation curb. This arrangement has two arms with a pin on each end, instead of sliding along the balance spring the gap between the two pins widened in cold weather and narrowed in hot, which has the same effect. Owing to the pincer-like appearance and action, this curb is commonly known as a “sugar-tong” compensation. It is thoug
Auctioneer:
Antiquorum
Date:
2005-11-13
