Dr. Klaus Hentschel University of Berne Switzerland Klaus Hentschel has been teaching history of science since 1990 as assistant professor and guest professor at the Universities of Hamburg, Gottingen and Stuttgart. With a senior research grant by the German National Research Association (DFG) and under the auspices of the University of Berne, Switzerland, he recently wrote a major study on the taxonomic arguments about the classification of radiant heat, light, and other forms of radiation between 1700 and 1900.