Jules Violle

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The Violle actinometer

Jules Louis Gabriel Violle (born November 16, 1841 in Langres , † September 12, 1923 in Fixin ) was a French physicist .

Youth and education

Violle comes from a family of mathematicians. His grandfather, Bernard Violle, was already occupied with mathematical puzzles and his father was a math teacher at the Collège de Langres . After completing secondary school , he studied experimentally at the École polytechnique and the École normal supérieure (ENS) before finally choosing the École normal . There he completed his studies in physics in 1864. In the same year he became a teacher at the high school in Besançon and finally in 1865 in Dijon . In 1870 Violle wrote a dissertation on the mechanical heat equivalent .

Live and act

In 1872 he was appointed professor of physics at the faculté de Siences in Grenoble . At that time Violle was concerned with the intensity of solar radiation. He constructed a measuring device to record the amount of heat. He wanted to know how much heat radiation hits an area of ​​1 cm². To do this, he placed a thermometer in an evacuated glass ball. Among other things, he found that the measurement results differed greatly despite the clear weather. This made him take his measurements at a place with the greatest possible difference in altitude, the Mont Blanc . To do this, he used an experimental setup in which two metal balls of the same size and weight were set up at different heights on the mountain. One sphere at the summit and one at the foot of the Bossons Glacier . He measured the heating of the balls over a period of one minute. This enabled him to prove that the atmosphere has an influence on the amount of heat that hits the earth's surface. He published his findings in 1875 in the book Une expédition au Mont-Blanc .

Based on his findings, Violle endeavored to determine the solar constant . He took the empirical approach . A number of measurements at different locations should result in an average value. Among other things, he had Paul Flatters carry out measurements on the northern border of the Sahara, in Laghouat , in 1877 . Together with Teisserenc , he also carried out measurements with weather balloons up to a height of 15 kilometers.

In 1879 he was appointed to the faculté de Siences in Lyon . There he carried out the evaluation of his research. He summarized these in a 76-page report entitled Sur la radiation solaire , which he presented to the 2nd International Meteorological Congress in Rome that same year. In 1879 Théodore Vautier also joined the Violles physical laboratory. There he prepared the experiments and later became his closest collaborator

In 1881, at the International Congress of Electricity in Paris, he introduced a new unit of measurement for light intensity , which was named the Violle unit . It corresponded to the amount of light that is emitted from the surface of one square centimeter of platinum when it reaches its melting point . It was the first unit for measuring light that was not derived from a specific type of lamp . However, it was soon replaced by the later valid unit candela .

In the years 1881 to 1882 he turned back to the behavior of metals when exposed to heat. He heated platinum, palladium and iridium in a glass flask to which a gas thermometer was connected and studied the behavior of the metals at different temperatures. He used this knowledge to develop an actinometer .

In 1891 he was appointed professor at the Conservatoire National des Arts et Métiers in Paris. There he experimented with the electric arc . He observed that the light output of the graphite electrodes was constant despite the continuously increasing power supply. From this he concluded that the temperature no longer rose either. From this knowledge he concluded the boiling point for graphite , which he believed to have determined at 2,600 ° at the time.

Violle also devoted himself to determining the speed of sound . Aware of the influence of temperature and humidity, he made his first attempt in 1885 with a 13 km long tube with a diameter of 70 cm. He also believed that amplitude and waveform affected the speed of sound. In 1895 he repeated the experiments with tubes of different lengths, between 3 and 25 km. He came to the conclusion that at 0 ° C and dry air the speed of sound is 331.15 m / s. Violle published his interim results on this research area from the start, always mentioning Théodore Vautiers as a collaborator.

Late years

Violle was a member of many committees and institutions, so he was elected to the Académie des Sciences in 1897 and a member of the Royal Institution of Great Britain in 1899 . Also from 1907 member of the Academie d'agriculture . Also from 1906 to 1908 he was president of the Société française de photographie . In 1915 he became head of the Commission supérieure des inventions intéressant la défense national (Commission for Defense Inventions). He was also one of the founders of the Institut d'optique théorique et appliquée and the École supérieure d'optique .

Violle was also the commander of the Legion of Honor .

Selected publications

  • Sur l'équivalent mécanique de la chaleur , dissertation, edited by Gauthier-Villars, Paris, 1870
  • Une expédition au Mont-Blanc , published by J. Claye, Paris, 1875
  • Sur la radiation solaire , edited by Gauthier-Villars, Paris, 1879.
  • Cours de Physique I , edited by G. Masson, Paris, 1883.
  • Sur la vitesse de propagation du son , with Théodore Vautier, 1885
  • Cours de Physique II , edited by G. Masson, Paris, 1888.
  • La rôle de la Physique a la Guerre , edited by Berger-Levrault, Paris / Nancy, 1915

literature

  • Mémoires de l'Académie des sciences, arts et belles-lettres de Dijon , Imprimerie Jobard , Dijon , 1928, pages 25 to 40

Web links

Individual evidence

  1. ↑ Traité complet des carrés magiques, in the Bibliothèque nationale de France , accessed on August 16, 2016
  2. ↑ Institute de Siences de l'Homme: Théodore Vautier , accessed 29 August 2016
  3. ^ Revue générale de l'électricité , in the Bibliothèque nationale de France , page 394, accessed on August 30, 2016
  4. ↑ Sur l'équivalent mécanique de la chaleur , in the "content": ["TH_000090_001_e0000002", true, "" } Bibliothèque nationale de France], accessed on August 24, 2016
  5. ↑ Une expédition au Mont-Blanc , in the Bibliothèque nationale de France , accessed on August 24, 2016
  6. ↑ Sur la radiation solaire , in the catalog of the Bibliothèque nationale de France , accessed on 23 August 2016
  7. ↑ Cours de Physique II , at archive.org , accessed on August 24, 2016
  8. ↑ Cours de Physique II , at archive.org , accessed on August 24, 2016
  9. ↑ La rôle de la Physique a la Guerre , in the Bibliothèque nationale de France , accessed on August 24, 2016
  10. ↑ Mémoires de l'Académie des sciences, arts et belles-lettres de Dijon , in the Bibliothèque nationale de France , pages 25 to 40, accessed on August 29, 2016
personal data
SURNAME Violle, Jules
ALTERNATIVE NAMES Violle, Jules Louis Gabriel (full name)
BRIEF DESCRIPTION French physicist and inventor
DATE OF BIRTH November 16, 1841
PLACE OF BIRTH Langres
DATE OF DEATH September 12, 1923
Place of death Fixin