Friedrich von Hefner-Alteneck

Friedrich Heinrich Philipp Franz von Hefner-Alteneck was a German electrical engineer and one of the closest aides of Werner von Siemens. He is largely remembered for the invention of the Hefner lamp, which provided the measure of luminous intensity used in Germany, Austria and Scandinavia from 1890 to 1942. The measure was called the Hefnerkerze (HK). The Hefnerkerze was superseded in the 1940s by the modern SI unit, the candela.