Roentgen
Roentgen names 2 different subjects across the 6 encyclopedias on this shelf. Each is set out below.
Roentgen or RÖNTGEN, RAYS
Collier's New Encyclopedia (1921)
or RÖNTGEN, RAYS, certain invisible non-refractable rays emanating from the surface of an electrically excited vacuum tube opposite the cathode electrode, having power (1) of permeating objects impervious to light or heat rays, (2) of discharging electrified bodies or surfaces exposed to them, (3) of exciting fluorescence in fluorescent salts, and (4) of affecting sensitized photographic plates in a manner similar to light rays. They were discovered by William Conrad Roentgen, Professor of Physics at the Royal University of Würzburg, in Germany, toward the close of the year 1895. Not being certain as to the nature of the rays, Professor Roentgen provisionally termed them the X-rays, and they are still commonly known by that name, though the name Roentgen rays is also common. At the beginning of 1894, Prof. P. E. A. Lenard, at Bonn, announced the discovery that by using a Crookes tube in which the cathode rays were made to impinge on a thin sheet of aluminum a screen covered with a phosphorescent substance outside the tube could be made to phosphoresce by their action. That, further, it was possible by means of these cathode rays, as he supposed, to obtain "shadows" of objects through optically opaque substances and to produce an impress of these "shadows" on photographic plates, which could afterward be developed and fixed by ordinary photographic processes. Working on this line of investigation Professor Roentgen inclosed an excited vacuum tube in black. ened cardboard treated with barium platino-cyanide, and discovered that the cathode beam is accompanied by certain rays not before known, which, though of phosphorescent and photographic quality, differ from any known form of light in not being susceptible of refraction. These were the wonderful X-rays, which have opened up to the world a new region of scientific exploration. Besides obtaining radiographs of the bones in the living human hand, Professor Roentgen radiographed a compass card completely inclosed in a metallic box. From these and similar experiments he inferred that these newly discovered rays generated in the neighborhood of the Crookes tube by the electric disturbance set up by the passage of a current possessed the property of passing through all bodies in their path, and that some bodies, being less permeable than others, cast a shadow. Subsequent experiments have established the fact that the transparency of a body to the X-rays is proportional to its density. As to the real nature of the X-rays eminent physicists differ, but all agree that they must be regarded as of a nature essentially different from ordinary light. They cast an invisible life-size shadow of the objects that obstruct their passage, which invisible shadow if received on a surface which phosphoresces or glows under their action becomes a visible shadow, which makes the wonderful revelations of the fluoroscope possible. If this invisible shadow is received on a sensitive plate, the plate is impressed, and on subsequent development the representation of the obstructing object is perpetuated on the photographic plate. The Roentgen rays pass very freely through the various tissues and fluids of the body, but are obstructed by the bones; hence it is possible to take a perfect shadow-picture, or radiograph, as it is now generally called, of the bones of a living person or animal. By far the most important result of the discovery has been the application of the new rays to surgery. Needles, bullets and other foreign objects in various parts of the body have been successfully located, and the invention of the FLUOROSCOPE (q. v.) has made it possible to use the Roentgen rays, not only in surgical cases, in searching for fractures, etc., but to undertake anatomical studies and make the diagnosis of internal diseases. The full physiological effects of the X-rays are not yet clearly understood. Experiments show that long exposure to the rays causes acute maladies of the skin and also baldness.
Roentgen WILLIAM CONRAD, VON, a German scientist
Collier's New Encyclopedia (1921)
WILLIAM CONRAD, VON, a German scientist; born in Prus- 1 WILLIAM CONRAD VON ROENTGEN sia in 1845; was graduated in medicine at the University of Zurich in 1869, and accompanied Professor Kundt, his teacher, to Würzburg, where he engaged in practice. He went to Strasburg, in 1873, as assistant professor, and for 20 years was conspicuous as Professor of Mathematics and Physics, and also as a scientist. In November, 1895, Roentgen made the discovery of what has since been known as the Roentgen, or X-rays. The German emperor bestowed the Order of the Royal Crown on the discoverer, who afterward also was ennobled. He received the Nobel Prize for physics in 1901.
What Has Changed in the Last Century
Collier's wrote in 1921 that "as to the real nature of the X-rays eminent physicists differ, but all agree that they must be regarded as of a nature essentially different from ordinary light" — in fact Max von Laue's 1912 crystal-diffraction experiment had already shown they are electromagnetic waves like light, only far shorter, and he and the Braggs took Nobel Prizes for it in 1914 and 1915. The caution that "the full physiological effects of the X-rays are not yet clearly understood" was tragically well placed: beyond the burns and baldness noted here, radiation was found to cause cancer, many early radiologists died of it, and dose limits, lead shielding and film badges became standard, while shoe-fitting fluoroscopes were banned outright by the 1970s. The shadow picture itself was transformed by Godfrey Hounsfield's computed tomography scanner in 1971, which reconstructs cross-sections rather than flat shadows. Roentgen, who never patented his discovery, died in Munich in 1923, two years after this account; element 111 was named roentgenium in his honour in 2004.
Written for this edition, 2026.