26,400 HKD
Vacheron & Constantin, Genève, No. 455035, case No. 286513. Made in the 1940s. Fine, large, silver-cased keyless deck lever chronometer with indirect centre seconds and Guillaume balance. To be sold without reserve Four-body, massive, "bassine", polished. Hinged silver cuvette. Brushed silver with champleve Arabic numerals, outer minute and seconds divisions and Arabic five minute/second numerals. Blued steel spade hands. Notes Anibal-Brass Guillaume Balance IInvented by the Nobel prize winner Dr. Charles Edouard Guillaume, it exhibits unusual properties, both in terms of thermal expansion and in changes in elasticity. These properties are very different from those of two other famous alloys invented by Guillaume, Invar and Elinvar. Around 1900 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 change of rate 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 by means of auxiliary compensation devices. In 1899, Guillaume noticed that steel with an addition of 44.4% nickel had a negative square coefficient of thermal expansion. This alloy, combined with brass in bimetallic lamina, makes its expansion close to
Auctioneer:
Antiquorum
Date:
2008-06-08
