59 



THE RONTGEN RAY, AND ITS RELATION TO PHYSICS 



(A TOPICAL DISCUSSION) 



[Transactions of the American Institute of Electrical Engineers, XIII, 

 403-410, 430, 431, 1896] 



OPENING REMABKS BY PROF. HENRY A. ROWLAND 



MR. PRESIDENT AND GENTLEMEN: A gentleman asked me a few mo- 

 ments ago if I knew anything about the X-ray. I told him no; that what 

 I was going to tell to-night was what I did not know about the X-ray. 

 I do not suppose anybody can do any more than that, because all of us 

 know very little about it. We were very much surprised, something 

 like a year ago, by this very great discovery. But I cannot say that we 

 know very much more about it now than we did then. The whole 

 world seems to have been working on it for all this time without having 

 discovered very much more with respect to it. 



Now, I suppose it is not necessary for me to go into the history of 

 the thing. We all know it; how Lenard first, probably, discovered these 

 rays, or discovered something very similar to them; how Rontgen after- 

 wards found their particular use, their penetrating power, and so on, 

 although Lenard had found something similar to that before. It is 

 thus not necessary for me to go into the history of the matter, but 

 simply to go over, to some extent, what we know with regard to these 

 rays at the present time. First, there was some discussion, some time 

 ago, as to the source of these rays. Rontgen found that their source 

 was any point that, the cathode rays struck upon; and you will remember 

 that when we first knew about these rays they were often called cathode 

 rays. Many persons thought that the cathode rays came through the 

 glass, and Lenard first thought that they did come through his little 

 window, and it is probable that they do at the present time. But the 

 kind of rays that we are considering are very different from the cathode 

 rays. Six months ago there was quite a discussion in regard to the 

 source, and I believe it was finally determined that they came from 

 points where the cathode rays strike. At the same time I was rather 

 opposed to that. In one of my tubes I found that the rays came from 



