Charles Edouard Guillaume
Born: 15 February 1861, Fleurier, Switzerland
Died: 13 June 1938, Sèvres, France
Affiliation at the time of the award: Bureau International des Poids et Mesures (International Bureau of Weights and Measures), Sèvres, France
Prize motivation: "in recognition of the service he has rendered to precision measurements in Physics by his discovery of anomalies in nickel steel alloys"
Prize share: 1/1
Precise measurement plays an important role in science. To provide a basis for precise measurements, the metric system and a German legal meter were instituted to define lengths. However, different materials expand differently when temperatures change, which limits the ability to make very precise measurements. In 1896 Charles-Edouard Guillaume succeeded in finding an alloy of nickel and steel that registered almost no change in length and volume as a result of temperature changes. The invar nickel-steel alloy had a significant effect on scientific instruments and incandescent light bulbs.