25,300 HKD
Ulysse Nardin, Locle, Chronomètre, Suisse, No. 127838, from a series of 402 pieces made in 1956.Fine and large silver keyless pocket chronometer with split-seconds chronograph and instantaneous 30-minute recorder, in original mahogany fitted box. Three-piece, massive, "bassine et filets", glazed. Silvered with bold Breguet numerals, outer Arabic mi-nute and chronograph rings, sunk subsidiary seconds and minute register. Blued steel Breguet hands. Notes Anibal (acier au nickel pour balanciers), an alloy invented by Dr. Charles Edouard Guillaume, 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. 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 iapproximately 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, combined wih brass in bimetallic lamina, makes
Auctioneer:
Antiquorum
Date:
2002-06-08
