As with most major discoveries, there are incremental observations and often theoretical analyses that lead to a final momentous breakthrough. This was not the case with the discovery of X-rays 125 years ago this year. In fact, a serendipitous discovery by Wilhelm Conrad Röntgen of immense consequence occurred during a repeat of another’s experiment.
On November 8, 1895, Röntgen was examining the range of cathode rays (electrons) in the air from a modified Crookes tube. He named these invisible rays ‘X-rays’ as they were hitherto unknown, and published a paper in late December 1895 entitled “A New Kind of Rays.” In this paper he presented the vast majority of the properties of X-rays. Some of these properties included:
their ability to penetrate paper, a 1,000 page book, glass, flesh, and various metals of differing thickness
the inability to refract in water, a prism, or mica
their ability to darken photographic plates
During the course of his investigations, he produced images of the barrel of a shotgun, other inanimate objects, and his wife’s hand on photographic plates. It was this aspect of X-rays that quickly led to their use in medicine, in particular imaging broken bones and finding foreign bodies (e.g., bullets).
The cold cathode tubes employed were very inefficient in X-ray production, unstable, unable to penetrate thick body areas, and took a significant period of time to produce an image on a plate. Those limitations were overcome by William David Coolidge (1873-1975), who was a physicist, chemist, research scientist, and invented the modern X-ray tube. Besides Röntgen, with his 1895 discovery and subsequent studies of X-rays, perhaps no other individual contributed more to the advancement of X-ray technology than did Coolidge.
From notes of interviews with Coolidge’s son Lawrence in the mid-1990s, previous biographies, publications, books, GE literature, historic photographs (e.g., a wonderful 1874 stereoview card with the one year old baby “Willie Coolidge”), and other artifacts in the authors’ collection, this presentation will review Dr. Coolidge’s amazing life, work, accomplishments, and awards. There will also be a brief review of the many applications of X-rays in medicine, research, and industry.