Charles Edouard Guillaume

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Charles Edouard Guillaume

Swiss scientist Charles–Edouard Guillaume (1861–1936) worked at the International Bureau of Weights and Measures for almost 50 years. His discovery of a steel–nickel alloy called invar that was impervious to temperature changes advanced science and technology. After discovering invar, he discovered a variation in the alloy called elinvar. When Guillaume received the Nobel Prize in Physics in 1920, the honor was not just in recognition of his discovery of iron–nickel steel alloys, however. He was also honored for his contributions to the field of metrology and his long career with the Bureau of Weights and Measures, where he helped establish international standards. His work in both alloys and metrology would have a profound impact on the world.

Early Life

Guillaume was born in Fleurier, Switzerland, on February 15, 1861. Guillame's family had originally been from France, but his grandfather, Charles Frederic Alexandre Guillaume, had left France for political reasons during the French Revolution that erupted in the last part of eighteenth century in France. He settled in England and established a successful watch–making business in London. The business was passed down to his three sons, including Edouard, Charles–Edouard Guillaume's father. Edouard Guillaume eventually relocated the business to Switzerland, when he settled in Fleurier. He later married and had Guillame in Switzerland.

Growing up in Switzerland, Charles–Edouard Guillaume received his early education at the Neuchâtel gymnasium. When he was 17 years old, he enrolled in the Zurich Polytechnic (which was later renamed the Federal Institute of Technology). At the Polytechnic, he quickly developed an interest in physics. He later indicated that François Arago's text book, Éloges académiques, was the major influencing factor that guided his decision about pursuing a career in science. He was awarded a Ph.D. in 1882 for his thesis on electrolytic capacitors. After graduation, he performed compulsory service for a year as an officer in the Swiss artillery. During this very short military career, Guillaume studied mechanics and ballistics.

International Bureau of Weights and Measures

In 1883, he accepted a position as an assistant at the International Bureau of Weights and Measures, which had just been established in Sevres, France, located just outside Paris. Guillaume joined the Bureau at an important time. Six years later, in 1889, the Bureau embarked on the approval and distribution, among all of the governments of the world, of metric standards.

Guillaume would remain with the Bureau for his entire career. In 1902, he became its associate director. From 1915 until his retirement in 1936, he was director of the Bureau. From 1936 until his death in that same year, Guillaume was honorary director.

Guillaume's earliest research at the Bureau involved thermometry. He conducted important investigations on corrections to mercury–in–glass thermometers. Also, he was responsible for the detailed calibration of thermometers used at the Bureau in the establishment of the thermal expansions of the standards of metrical length. He was engaged in establishing, duplicating, and distributing the international metric standards, and he worked on determining the volume of one kilogram of water by the contact method.

Accidentally Discovered Invar

It was the work involving calibration that led Guillaume to the accidental discovery that would make him famous and lead to his Nobel Prize. A chance observation by Guillaume on the coefficient of expansion of nickel–iron alloys led to investigations of alloys and culminated in the discovery of "invar," an alloy with a very low coefficient of expansion, and later would lead to the discovery of elinvar, which has an extremely low thermoelastic coefficient over a large temperature range.

Among his duties at the Bureau, Guillaume was charged with making precise copies of the standard meter for distribution to countries around the world. The standard meter bar kept at the Bureau had been made of a platinum–iridium alloy, developed by Henri Sainte–Claire–Deville, to prevent corrosion and changes due to temperature. The hardness, permanence, and resistance to chemical agents would be perfect for standards that would have to last for years and years.

However, duplicating the standard meter bar would simply cost too much money, as the metals used to make it were too expensive. Seeking a solution, Guillaume began investigating other potential materials that could be used to make duplicates of the meter bar.

In 1896, Guillaume was studying the properties of iron–nickel alloys (or ferronickel alloys). He melted various ferronickel alloys, experimenting with different nickel contents (from thirty percent to sixty percent nickel). He found that the coefficient of expansion at room temperature was lowest at a nickel level of 36–percent (to the 64–percent iron level). In fact, an alloy with that percentage of nickel exhibited the least amount of thermal expansion of any alloy known. Guillaume considered the expansion of this new alloy "invariable," so he eventually named it invar.

Practical Applications of Invar

The value of invar to metrology was immediately apparent. It was economically feasible to duplicate the standard meter bar. Moreover, measuring devices such as the bar that were made of the alloy containing a 36–percent nickel content would not change in size due to changes in temperature. However, it did not take long for people to perceive its value to other fields. Soon the alloy was being applied to clock–making. It was necessary that pendulum rods maintain the same length regardless of temperature, and invar would ensure that the lengths were maintained. Previously, clockmakers needed to equip the very best clocks—the ones with the highest levels of precision—with some form of expansion–compensation device. The warming of the steel rods used in pendulums resulted in a loss of 0.5 second–per–degree Celsius a day, or 0.28 second–per–degree Fahrenheit a day.

Ferronickel alloys quickly became widely used in other instruments of precision, as well as in surveying tapes and wires. Later, it would be used in light bulbs and in the electronic vacuum tubes that once were used in radios. In addition, the alloy became a substitute for platinum for glass sealing wire, which resulted in huge cost savings for manufacturers.

With each new decade, it seemed that more uses for the alloy were being found. In the 1930s, ferronickel alloys proved useful in thermostats for temperature control, and they were used to make measuring devices for testing gauges and machine parts. During World War II, there was a great demand for the alloys in the United States Armed Forces.

Awarded the Nobel Prize

However, invar's potential impact on the world was recognized almost as soon at Guillaume announced its discovery. By 1920, its importance to the advancement of science and technology was so obvious that it earned Guillaume that year's Nobel Prize in Physics. Moreover, Guillaume became the first and only scientist in history to be recognized by the Swedish Academy of Sciences for a metallurgical achievement.

In presenting the award to Guillaume, the Academy lauded both his efforts in helping establish an international metric standard and in developing the ferronickel alloy. "Charles–Edouard Guillaume is undeniably the foremost metrologist of today," the Academy said. "By devoting his entire life to the service of science, [he] has made a powerful contribution to the progress of the metric system; during his long and painstaking studies he discovered a metal with the most excellent metrological properties. . . . the discovery is of great significance for the precision of scientific measurements and thereby even for the development of science in general."

However, Guillaume was not finished making discoveries in alloys. In the early 1920s, working in collaboration with Chenevard and the Imphy steel laboratory, he developed a variation of invar called elinvar (a contraction of elasticité invariable). Elinvar was an improvement over invar in that its thermoelastic coefficient is essentially zero. Also, it is less susceptible to the effects of magnetism and oxidation.

Later Applications

The use of invar has continued for more than a century, and its importance has grown as the years have gone by, as it led to new or improved technologies. Ferronickel alloys are valuable in a wide range of applications. With its low coefficient of expansion, as well as its wide and easy availability, the 36–percent nickel alloy has become one of the most commonly used materials for applications that require low expansivity. It became the most commonly used ferronickel alloy in applications such as electronic devices, where size changes due to temperature must be minimized, and it makes up some parts in precision optical measuring devices.

As the United States experienced a period of historically unprecedented prosperity in the 1950s and the 1960s, the use of 36–percent alloy and other ferronickel alloys became even more widespread in new technological devices such as circuit breakers, motor controls, TV temperature compensating springs, appliance and heater thermostats, automotive controls, heating, and air conditioning.

Later, invar resulted in a whole new breed of low expansion, nickel–iron alloys, as the use of the 36–percent did not prove useful in all applications. Invar has the lowest thermal expansivity, but it also has the lowest Curie Temperature (the temperature at which a material loses it magnetic properties), which limits its usefulness in certain potential applications. However, other alloys in the so–called "invar family" alleviate that problem. Other ferronickel alloys became used in a variety of commercial and technological applications such as semiconductors, high–definition television, information technology devices, aeronautical devices, and cryogenic transport. The most recent applications of ferronickel alloys include use as structural components in precision laser and optical measuring systems and wave guide tubes, in microscopes, and in support systems for giant mirrors in telescopes. The aerospace industry has used 36–percent alloys to make composite molds in new generations of aircraft. The alloys are also used in orbiting satellites and laser gyroscopes. It is expected that ferronickel alloys will have a growing impact on science and technology throughout the twenty–first century.

Distinguished Career

Records of Guillaume's research can be found in the many papers published by the International Bureau of Weights and Measures. In addition, Guillaume himself wrote Études thermométriques (Studies on Thermometry, 1886), Traité de thermométrie (Treatise on Thermometry, 1889), Unités et Étalons (Units and Standards, 1894), Les rayons X (X–Rays, 1896), Recherches sur le nickel et ses alliages (Investigations on Nickel and its Alloys, 1898), La vie de la matière (The Life of Matter, 1899), La Convention du Mètre et le Bureau international des Poids et Mesures (Metrical Convention and the International Bureau of Weights and Measures, 1902), Les applications des aciers au nickel (Applications of Nickel–Steels, 1904), Des états de la matière (States of Matter, 1907), Les récent progrès du système métrique (Recent progress in the Metric System, 1907, 1913), and many more essays. His book, Initiation à la Mécanique (Introduction to Mechanics), was translated into several languages.

Beside the Nobel Prize, Guillaume received distinctions and honors throughout his career. He was appointed Grand Officer of the Legion of Honour and received honorary Doctor of Science degrees from the Universities of Geneva, Neuchatel, and Paris. He was a President of the Sociétá Française de Physique. In addition, he was a member, honorary member or corresponding member of more than a dozen of the leading scientific academies of Europe. In 1888, Guillaume married A. M. Taufflieb. They had three children. He died on May 13, 1938, in Sevres, France.


Notable Scientists: From 1900 to the Present, Gale Group, 2001. World of Scientific Discovery, Second Edition, Gale Group, 1999.


"Charles–Edouard Guillaume–Biography," Nobel Prize Website, (January 12, 2005).

Harner, Leslie, "After 100 Years, the Uses for Invar Continue to Multiply," Center for Materials Science and Engineering, (January 12, 2005).

Nicolet, J.C., "Questions in Time," Europa Star,–tech/nicolet6.jsp (January 12, 2005).

"The Nobel Prize in Physics 1920–Presentation Speech," Nobel Prize Website, (January 12, 2005).

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Guillaume, Charles Édouard

(b. Fleurier, Switzerland, 15 February 1861; d. Sèvres, France, 13 June 1938)

metallurgy, physica.

Guillaume’s father, Édouard Guillaume, returned to Switzerland, his family’s original home, from London, where he had managed a clockmaking firm. His knowledge of science was considerable, and he was his son’s first teacher. The latter was admitted at the age of seventeen to the Zurich Polytechnikum, where he studied not only the prescribed scientific subjects but also German and Frencch literature. He used to say that François Arago’s Éloges académiques had exerted a profound influence on him.

In 1883 Guillaume entered the International Bureau of Weights and Measures at Sèvres,, near Paris. He remained there throughout his career and became its director. In 1911 he was elected a corresponding member of the physics section of the Académie des Sciences.

Guillaume’s first works were devoted to the mercury thermometer; upon completion of these studies he published a treatise on thermometry which made available to physicists the methods perfected by the International Bureau of Weights and Measures. He next participated in the preparation of the national meters, a fundamental work which marked the origin of modern metrology and permitted the presentation in 1889, at the first Conference on Weights and Measures, of the complete collection of standardized meters destined for the different countries.

Since 1890, Guillaume was led to undertake investigations on metal alloys. Studies had been made at Sévres on a ferronickel (an alloy of iron with 24 percent nickel and 2 percent chromium) that had just been created at the Imphy Works in Nièvre. This alloy was more expansible than the iron or the nickel composing it. While studying an alloy containing slightly more nickel, Guillaume observed that this small variation in composition resulted in an alloy less expansible than the constituent metals. He undertook a methodical study of ferronickels and showed that with 36 percent nickel, one obtained an alloy, which he called invar, that expanded ten times less than iron and that even possessed a zero coefficient of dilatation after appropriate tempering, drawing, and rolling.

This alloy immediately found numerous applications, particularly in clockmaking. Guillaume also helped to solve another problem—compensation in ordinary watches—through his discovery of elinvar, an alloy whose elasticity does not vary with temperature.

These successes gave Guillaume an important role in the International Physics Congress, held in Paris in 1900, and earned him the 1920 Nobel Prize in physics. Moreover, he had the pleasure of seeing that his work would be brilliantly continued at the International Bureau of Weights and Measures by the physicist Albert Pérard, who succeeded him as director. In addition, Albert Portevin and Pierre Chevenard obtained very satisfactory results in developing his researches on nickel alloys.


Guillaume’s works include “Sur la dilatation des aciers au nickel,” in Comptes rendus hebdomadaires des séances, de l’Académie des sciences, 124 (1897), 176; “Recherches sur les aciers au nickel. Proptiétes métrologiques,” ibid., 752; “Recherches sur les aciers au nickel. Propriétés magnétiques et déformations permanentes;” ibid., 1515; Recherches sur les aciers au nickel. Dilatations aux températures élevées; résistance électrique,” ibid., 125 (1897), 235, errata, p. 342; “Recherches sur les aciers au nickel. Variations de volumes des alliages irréversibles,” ibid., 126 (1898), 738; “Nouvelles recherches sur la dilatation des aciers au nickel,” ibid., 136 (1903), 303; “Changements passagers et permanents des aciers au nickel,” ibid., 357; “Variations du module d’élasticité des aciers au nickel,” ibid., 498; “Sur la théorie des aciers au nickel,” ibid., 1638; L’anomalie de dilatation des aciers au nickel,” ibid., 152 (1911), 189; “Coefficient du terme quadratique dans la formule de dilatation des aciers au nickel,” ibid., 1450; “Modification de la dilatabilité de l’invar par des actions mécaniques ou thermiques,” ibid., 163 (1916), 655; “Écrouissage et dilatabilité de l’invar,” ibid., 741; “Homogénéité de dilatation de l’invar,” ibid., 966; “Recherches métrologiques sur les aciers au nickel,” in Travaux et mémoires du Bureau international des poids et mesures, 17 (1927); “Les anomalies des aciers au nickel et leurs applications,” in Revue de métallurgie, 25 (1928), 35.

Georges Chaudron