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
David Roentgen flat-pack home assembly without an allen key. According to his biography in the Encyclopædia Britannica Eleventh Edition of 1911, Roentgen was not a great cabinetmaker: "His forms were often clumsy, ungraceful, and commonplace; his furniture lacked the artistry of the French and the English cabinetmakers of the great period which came to an end about 1790. His bronzes were poor in design and coarse in execution; his work, in short, is tainted by commercialism. As an inlayer, however, he holds a position of high distinction. His marquetry is bolder and more vigorous than that of Riesener, who in other respects