Roentgen (unit) Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. In 1928 it was the first international measurement quantity for ionising radiation to be defined for radiation protection, and was an easily replicated method of measuring air ionization directly by using an ion chamber. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays. Although relatively easy to measure, it had
Wilhelm Stier - 1999, Professor at the Techical University of Graz, Austria Wilhelm Stier - Familytree - Family member. Wilhelm Stier Wilhelm Stier (born May 8, 1799 in Błonie near Warsaw, died September 19, 1856 in Schöneberg, full name: Friedrich Ludwig Wilhelm Stier) was a German architect and university teacher at the Berlin Bauakademie. Wilhelm Stier was born the son of Christiane Eleonora Stiers 1766 - & Friedrich Ludewik Stier 1765 - 1815 a German postmaster & taxman in the then Prussian province of South Prussia & then Wilhelms family moved to Silesia. Wilhelm Stier was Grand son to Medical Officer /