Wilhelm Conrad Roentgen
The German physicist Wilhelm Conrad Roentgen, b. Mar. 27, 1845,
d. Feb. 10, 1923, discovered X rays, for which he received (1901)
the first Nobel Prize for physics. He observed (1895) that barium
platinocyanide crystals across the room fluoresced whenever he
turned on a Crooke's, or cathode-ray discharge, tube, even when
the tube, an electron emitter, was shielded by black cardboard or
thin metal sheets. Roentgen correctly hypothesized that a
previously unknown form of radiation of very short wavelength was
involved, and that these X rays (a term he coined) caused the
crystals to glow. He later demonstrated the metallurgical and
medical use of X rays.