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| Jules Violle | |
|---|---|
| Name | Jules Violle |
| Birth date | 16 November 1841 |
| Birth place | Langres, Haute-Marne, France |
| Death date | 12 September 1923 |
| Death place | Lyon, Rhône, France |
| Nationality | French |
| Fields | Physics, Radiometry, Metrology |
| Workplaces | École Polytechnique, Conservatoire des Arts et Métiers, University of Lyon |
| Alma mater | École Normale Supérieure, École Polytechnique |
| Known for | Absolute measurement of solar radiation, Violle unit of temperature |
Jules Violle (16 November 1841 – 12 September 1923) was a French physicist and inventor noted for experimental work on radiometry, thermometry, and solar constant measurement. He taught at major French institutions, conducted field campaigns to measure solar radiation, devised instruments for absolute temperature and luminous intensity determinations, and influenced early metrology. Violle’s career intersected with prominent figures and institutions across 19th and early 20th century European and international science.
Born in Langres, Haute-Marne, Violle studied at École Normale Supérieure and École Polytechnique where he trained in mathematics and physics amid contemporaries linked to Louis Pasteur, Marcellin Berthelot, Hector Berlioz, and the scientific milieu of Paris. He was a student during the period shaped by reforms associated with Jules Ferry and the Third Republic, attending lectures influenced by scientists from Collège de France and researchers active at École des Mines de Paris. Early exposure to experimental practice connected him with laboratories at Muséum national d'Histoire naturelle and the instrument makers around Rue Vivienne and Rue de Seine in Paris.
Violle held teaching and research posts at institutions including Conservatoire des Arts et Métiers, École Polytechnique, and the University of Lyon. He lectured alongside professors from Sorbonne, shared academic networks with figures at Collège de France and collaborated with staff at Observatoire de Paris. His pedagogical work linked him to curricula reorganization influenced by ministries under Gambetta and Ferry, and to examination boards tied to agrégation and technical commissions associated with Ministry of Public Instruction.
Violle conducted pioneering measurements of solar radiation, mounting expeditions to high-altitude sites such as Mont Blanc and station networks akin to those used later by international meteorological services. He aimed to determine the solar constant by means similar to approaches used by Samuel Pierpont Langley, J. Norman Lockyer, and contemporaries at Greenwich. Violle’s radiometric studies intersected with thermodynamic theories from Sadi Carnot, Rudolf Clausius, and experimental frameworks developed by James Clerk Maxwell and Hermann von Helmholtz. His determinations of absolute temperature and luminous intensity dialogued with metrological work by Gustave-Adolphe Hirn, Jean-Baptiste Biot, and Auguste Bravais and informed later standards set by BIPM and committees influenced by Giuseppe Mercalli in seismic and geophysical contexts.
Violle designed radiometers, calorimeters, and pyrheliometers, instruments in the lineage of devices by John Tyndall, Crookes, and Nichols and Hull. He proposed an absolute unit of temperature (the Violle unit) intended for practical metrology alongside scales from Anders Celsius, Daniel Gabriel Fahrenheit, and methods later formalized by William Thomson, 1st Baron Kelvin. His work contributed to international discussion at meetings of organizations like International Committee for Weights and Measures and exchanges with the laboratories of PTB and NPL. Violle’s instrument designs were manufactured by Paris workshops and competed with apparatus from Edmund C. Berkeley and precision firms tied to Rue de l'Université suppliers.
Violle authored scientific papers and books reporting experimental results and methodological advances, publishing in venues contemporaneous with Comptes rendus de l'Académie des Sciences and periodicals similar to Annales de chimie et de physique, Philosophical Magazine, and proceedings of institutions such as Société française de physique and Académie des Sciences. He communicated results at meetings with peers from Royal Society, Deutsche Physikalische Gesellschaft, and engineering societies related to Société des Ingénieurs Civils de France. His written contributions informed textbooks and manuals used in technical education at École Centrale Paris and Mines ParisTech.
Violle received recognition from scientific bodies including election to assemblies like Académie des Sciences sections and participation in international congresses such as International Congresses of Physicists. He influenced metrology and solar physics, with the Violle unit cited in historical reviews alongside units promoted by BIPM and figures like Adolphe Quetelet and Henri Poincaré. His students and collaborators went on to roles at institutions including Observatoire de Paris, École Polytechnique, and industrial laboratories connected to firms such as Schneider Electric and early electrical engineering groups. Violle’s legacy persists in histories of radiometry, metrology, and French scientific education in the eras shaped by Third French Republic science policy and international standardization movements.
Category:French physicists Category:1841 births Category:1923 deaths