Anders Celsius magnitude (a measure of brightness) of certain stars. This was the first attempt to measure the intensity of starlight with a tool other than the human eye. He made observations of eclipses and various astronomical objects and published catalogues of carefully determined magnitudes for some 300 stars using his own photometric system (mean error=0.4 mag). Celsius was the first to perform and publish careful experiments aiming at the definition of an international temperature scale on scientific grounds. In his Swedish paper "Observations of two persistent degrees on a thermometer" he reports on experiments to check that the freezing point is
Anders Henrik Bull Anders Henrik Bull Anders Henrik Bull (25 January 1875 – after 1909) was a Norwegian electrical engineer. He was born in Minneapolis as the son of ophthalmologist Ole Bornemann Bull (1842–1916) and his first wife Marie Cathrine Lund (1843–1884). The family moved to Norway in 1876. He took his engineering education in Kristiania and Hannover. He returned to Norway from Hannover in 1901, and became noted in the engineering community for his pioneering work on wireless telegraphy. He also worked for Norsk Hydro, as a consultant to Kristian Birkeland, from 1906 to 1909, in that company's formative phase. He married