554 POPULAR SCIENCE MONTHLY 



THE STOEY OF PROFESSOR RONTGEN'S DISCOVERY 



By ELMER ELLSWORTH BURNS 



CHICAGO, ILL. 



THE discovery of X-rays was announced by Professor Rontgen in 

 December, 1895, in a communication to the Physico-medical As- 

 sociation of Wiirzburg. The date of the discovery is commonly thought 

 to be November, 1895. As a matter of fact, the first X-ray photo- 

 graph was made about two years before that time, and the accidental 

 production of this photograph was the starting point of a series of in- 

 vestigations which continued for more than two years before the public 

 announcement was made. The story was told to me by Dr. T. S. 

 Middleton, now a physician in Chicago, who was a research student 

 under Professor Rontgen during a period of four years, including the 

 time when the great discovery was made. 



Professor Rontgen is a man who works unceasingly as a teacher and 

 in research, a man who brings to his students the inspiration of genius. 

 Like Edison, he would often forget to eat were he not reminded by 

 friends of his need of food. 



He was working with cathode rays and, being an expert glass 

 blower, prepared his own tubes. He had a habit of using his lungs as 

 an air-pump in exhausting his tubes. Long practise had developed an 

 athletic pair of lungs, so that he was able in this manner, aided by the 

 increase in vacuum due to the electric discharge, to produce a vacuum 

 sufficiently high for the production of the cathode rays. The first 

 X-ray tube was exhausted in this way. This tube was blown to form 

 a large bulb at the middle and bent to form a letter S at either end. 



The electrodes being at the ends, the cathode rays would have to 

 traverse the bends of the tube. Rontgen regarded the cathode rays as 

 streams of electrified particles and believed that friction would be de- 

 veloped as these particles streamed past the bends of the tube. He 

 expected this friction to result in new phenomena. 



On a flat-topped desk in Professor Rontgen's private office lay an 

 unassorted heap of books, glass tubes, photographic plate holders, 

 platinum and aluminium electrodes, and what-not, such an unassorted 

 heap as is likely to accumulate on the desk of a busy man. In this 

 confusion it happened that a large book which the professor had been 

 reading lay on a photographic plate holder. In the book lay a key 

 serving as a bookmark. The use of a flat key as a bookmark is a pe- 



