Jules-Louis-Gabriel ViolleDied 12 Sep 1923 at age 81 (born 16 Nov 1841).French physicist who made the first high-altitude determination of the solar constant (1875, on Mont Blanc in the French-Swiss Alps). He also determined the fusion points of palladium, platinum and gold. Violle also was interested in the theory of geysers, the origin of hail, and atmospheric exploration through balloon soundings. For high-temperature radiation, he proposed a photometric unit, the violle or Violle's standard (1881). His actinometer is one form of pyrheliometer, a device to measure the intensity of sunlight. It was modified from John Herschel's invention of 1825. It consists of two concentric hollow spheres containing water between them. Sunlight passes through an aperture and falls on a thermometer bulb in the hollow inner sphere. |
