Jules Louis Gabriel Violle (16 November 1841 – 12 September 1923) was a French physicist and inventor.
[1] He is notable for having determined the solar constant at Mont Blanc in 1875, and, in 1881, for proposing a standard for luminous intensity, called the Violle, equal to the light emitted by 1 cm² of platinum at its melting point.
This was much larger than traditional measures such as candlepower, so the standard SI unit candela was originally defined in 1946 as 1/60 Violle.
During his career, Violle taught at several colleges including the University of Lyon and the Conservatoire des Arts et Métiers in Paris.
He improved and invented a number of devices for measuring radiation, and determined the freezing and melting points of palladium.