ASNT

The commercial community took note of Röntgen’s discovery (Glasser 1934; Eisenberg 1992). An American industrial group was said to offer Röntgen a fortune for rights to his discovery. Röntgen was similarly approached by many industrial groups, including a German company. However, he remained true to his scientific calling, saying that discoveries and inventions belong to humanity and that they should not in any way be hampered by patents, licenses, or contracts, nor should they be controlled by any one group. Thomas A. Edison, the renowned American inventor, was among the first of many Americans to investigate X-rays. He quickly designed and built X-ray tubes and a f luorescent screen f luoroscope, making use of his own discovery that a calcium tungstate phosphor screen gave very bright X-ray images. Edison exhibited an X-ray f luoroscope at the National Electrical Exposition at the Grand Central Palace in New York in May 1896. The Exposition gave the general public a rare opportu- nity to see X-ray pictures. Obviously, with crookes tubes in use in laboratories around the world, it is clear that many people before Röntgen had produced X-rays. Once the discovery was announced, many scientists recognized that X-rays had been responsible for strange effects they had noticed (but not followed up) from earlier experiments. Crookes often rejected photographic plates because they fogged, most likely from X-ray exposure. Philipp Lenard, who had helped Röntgen obtain one of his thin window tubes, had noticed that an electric charge some distance away from his lenard tube was discharged, but he did not investigate fully (Lenard 1894). One well-documented early notice of X-rays occurred in the physics laboratory of Arthur W. Goodspeed at the University of Pennsylvania (Grigg 1965). He was visited in February 1890 by photogra- pher William Jennings to do some photography with spark discharges. After the young men finished with the spark equipment, Goodspeed showed Jennings his crookes tube equipment in operation. Jennings had several unexposed, covered photographic plates on the table during the crookes tube demonstration; he had placed several coins for his carfare on top of the stack of plates.

On returning to his laboratory, he processed the plates and found a curious image of several round objects. He dated and filed the plate, only to bring it back at Goodspeed’s request after the news of the X-ray discovery. They could document that they had made an X-radiograph five years before Röntgen’s discovery. Goodspeed and Jennings merely brought the radiograph to public attention, never claiming any credit for discovering X-rays. Röntgen himself published two additional scientific papers about X-rays. “On a New Kind of Rays, Continued,” (Röntgen 1895) was published by the same Würzburg publication in March 1896 and was followed by “Further Observations on the Properties of X-Rays, ” (Röntgen 1897) published in March 1897 by the Prussian Academy of Sciences. His three scientific papers presented thorough results about X-rays. His investigations showed the penetrating power of the new rays as related to the density of the absorber and the effect on f luorescent materials and photographic film. Röntgen took pinhole pictures to confirm that the source of the X-ray emission was the point where the cathode rays struck the glass wall or a metal target. He recognized the nonuniform distribution of the X-ray emission from the target and found the fundamen- tals of the inverse square law for decreasing X-ray intensity with increasing distance from the target. He tried without success to def lect the X-ray beam with a magnet or an electric field. His attempts to demonstrate ref lection and diffraction were likewise without success. His experiments did produce evidence that the new rays caused electri- cal conductivity in air and that heavy metal targets, such as platinum, produced more intense X-ray beams than glass or aluminum targets. His three papers on X-rays gave the basic information about X-rays to the world (Henning 1987). Early Medical Applications The medical use of X-rays began immediately. It was straightforward to recognize the usefulness of X-rays to find foreign objects in the body and to help set broken bones. There are many documented instances of such applications as early as January and February 1896. The first recorded X-ray picture in the Americas was taken by Arthur W. Wright of

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Part 2