10,580 CHF
Ulysse Nardin, Locle & Geneva, No. 19685, circa 1928. Very fine and rare silver center-seconds, keyless, dead half-seconds deck chronometer in ebony fitted box. Three-body, “bassine et filets”, polished, glazed back. White enamel, bold radial Roman numerals, outer minute/seconds ring. Blued steel “spade” hands. 45 mm (20’’’), frosted gilt half plate, Earnshaw-type spring detent chronometer escapement, steel escape wheel, Guillaume anibal-brass balance with special balance spring with outer terminal curve, 15 jewels, escapement capped, cock with diamond endstone. Signed on dial and movement. Diam. 64 mm. Notes Deck chronometers with center-seconds are rare. Guillaume balance Anibal (acier au nickel pour balanciers), an alloy invented by Dr. Charles Edouard Guillaume, exhibits unusual properties, both in terms of thermal expansion and of changes in elasticity. These properties are very different from those of two other famous alloys invented by Guillaume, Invar and Elinvar. At the end of the 1800’s, Guillaume attempted to eliminate the so-called Middle Temperature Error caused by the fact that the change of rate in a timekeeper with a steel-brass bimetallic balance is approximately a linear function of temperature, while the modification caused by change in elasticity of a balance spring is approximately a quadratic function. Thus, it equals zero at only two temperatures, causing secondary error. Countless attempts were made to eliminate Middle Temperature Error, usually
Auctioneer:
Antiquorum
Date:
2002-04-13
