Jules Louis Gabriel Violle (16.11.1841 —12.09.1923) was a French physicist and a member of the Paris Academy of Sciences (1897). He was born in Langres. He graduated from the École Normale in Paris and in 1870 received the degree of Doctor of Science. From 1879 he was professor at the University of Grenoble, from 1884 at the École Normale, and from 1892 at the Conservatoire des Arts et Métiers (Paris).
His work was in the fields of heat, molecular physics and optics. He determined the solar constant and the temperature of the Sun (1877) and the mechanical equivalent of heat. In 1881 he proposed a photometric unit, the platinum unit of light, which in 1884 was adopted as a standard at an international conference. He constructed (1882) a calorimeter whose principle was used in the vacuum flask. He studied geysers and the formation of hail, and carried out atmospheric research with the help of balloons.