Important Watches, Collector's Wrist...

Hong Kong, Jun 08, 2001

LOT 308

Ulysse Nardin, Locle, Suisse,No. 124293, case No. 658655, circa 1935.Fine stainless steel, keyless center seconds deck-watch.

C. Three-body, ?bassine et filets?, polished, screwed back cover with reeded edge, hinged "Staybrite" cuvette. D. White enamel with Roman chapters, outer Arabic minute and seconds ring. Blued steel ?spade? hands. M. 52 mm ø, frosted and gilt, 23 jewels, straight-line lever escapement, anibal-brass Guillaume balance, blued steel Breguet balance spring with terminal curve and swan neck micrometric index.Signed on the dial, case and movement.Diam. 64 mmAnibal (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 modifications 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 witbrass in bimetallic lamina, makes its expansion close to quadratic. Balances with bimetallic rims made of anibal and brass are usually called Guillaume balances, or, as their inventor called them, integral balances. When combined with special balance springs, they exhibit remarkable temperature stability, on occasion not exceeding 1/50 second per day at 1oC.