In 1895, Wilhelm Conrad Roentgen accidentally observed andthrough meticulous scientific investigationdefined a new type of electromagnetic radiation.
While working with a Crookes' Tube cathode ray generator, covered at the time, he noticed a glow produced in an adjacent barium platinocyanide sample. Investigation showed the fluorescence was caused by radiation originating in the Crookes' Tube, which penetrated the covering to reach the platinum compound to glow. Roentgen named his discovery "X-rays."
X-rays are the radiation given off when an electron traveling at high speed strikes a metal target. The rays rank next-to-highest in the electromagnetic spectrum; only gamma rays from nuclear decay have greater penetrating power.
The ability to penetrate tissue to varying degrees makes X-rays an important, non-invasive, investigative tool in diagnosis and treatment in both medicine and in chemical analysis. As X-rays pass through the body, they are blocked, to a greater or lesser degree, by internal organs. A photographic plate placed at the spot where the X-rays exit contains the resulting shadow picture of the internal contents.
Committee Secretary to James Barnes, Informing of the Sub-Committee's unanimous decision on the Potts Medal award, 4/30/1926. (467K)
Committee Secretary to Frederic Palmer, Jr., Requesting that Palmer bring his Coolidge Tube so that the Sub-Committee may examine it, 5/3/1926. (450K)
Committee Secretary to William D. Coolidge, Informing Coolidge of his nomination as the Howard N. Potts medal winner and requesting his presence at the award ceremony, 7/1/1926. (582K)