THE WILDE LECTURE. 



XV. On the Nature of the Rontgen Rays 



By Sir G. G. Stokes, Bart., F.R.S. 



Delivered July 2nd, 1897. 



Ever since the remarkable discovery of Professor 

 Rontgen was published, the subject has attracted a 

 great deal of attention in all civilised countries, and 

 numbers of physicists have worked experimentally, 

 endeavouring to make out the laws of these rays, to 

 determine their nature if possible, and to arrange for 

 their application. I am sorry to say that I have not 

 myself worked experimentally at the subject ; and that 

 being the case, there is a certain amount of presumption 

 perhaps in my venturing to lecture on it. Still, I have 

 followed pretty well what has been done by others, and 

 the subject borders very closely on one to which I 

 have paid considerable attention ; that is, the subject 

 of light. 



In Rontgen's original paper he stated that it was 

 shown experimentally that the seat of these remarkable 

 rays was the place where the so-called cathodic rays 

 fall on the opposite wall of the highly-exhausted tube in 

 which they are produced. I will not stop to describe 

 what is meant by cathodic rays. It would take me too 

 much away from my subject, and I may assume, I 

 think, that the audience I am now addressing know what 

 is meant by that term. This statement of Rontgen's 

 was not, I think, universally accepted. Some experi- 

 mentalists set themselves to investigate the point by 



September 22nd, 1897. 



