Roentgen (unit) this derivative quantity the roentgen equivalent physical (rep) to distinguish it from the ICR roentgen. The introduction of the roentgen measurement unit, which relied upon measuring the ionisation of air, replaced earlier less accurate practices that relied on timed exposure, film exposure, or fluorescence. This led the way to setting exposure limits,and the National Council on Radiation Protection and Measurements of the United States established the first formal dose limit in 1931 as 0.1 roentgen per day. The International X-ray and Radium Protection Committee, now known as the International Commission on Radiological Protection (ICRP) soon followed with a limit of
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