On the Reflection of Cathode Bays. 395 



The writer has previously described* how with an anticathode, 

 inclined at an angle of 45 to the axis of a conical cathode stream, he 

 found, by examination with a pin-hole camera, that those portions of 

 the stream which impinge most normally upon the anticathode are the 

 most efficient in producing Rontgen rays, while those portions of the 

 stream which strike the anticathode surface very much on the slant 

 are less efficient in producing Rontgen rays. There is probably some 

 connection between this and what is indicated in Tables X and XL 

 The fact that the more normal is the angle of incidence, the greater 

 is the amount of negative charge imparted to the anticathode reflector, 

 the greater the amount of Rontgen rays produced, and the less the 

 amount of charge in the reflected cathode rays, would seem to support 

 the view that the Rontgen rays are actually generated in some way 

 by the electric charges carried by the cathode ray particles being 

 imparted to the anticathode. 



Conclusion. 



The results of the experiments described above differ in at least one 

 important particular from those obtained by Mr. H. Starke, an account 

 of whose researches appeared in Wiedemann's ' Annalen,' No. 9, p. 56, 

 1898, while the writer's investigatons were in progress. Mr. Starke,. 

 using a form of tube in which the arrangement of cathode, anode, and 

 reflector was very similar to that shown in fig. 9, but with a Faraday 

 cylinder fixed in one definite position, as in the tube illustrated in 

 fig. 2, and using the galvanometer method of measuring the charge con- 

 veyed to the cylinder by the reflected cathode rays, appears to have found 

 that so long as the same face of the reflector was turned towards both 

 the cathode and cylinder, the orientation of the reflector did not affect the 

 amount of charge conveyed to the cylinder. This is so totally at variance 

 with the results given above, which were repeated over and over again, 

 that the writer can only assume that the methods employed by Mr. 

 Starke were not as sensitive as his own, particularly as in the case of 

 the writer's results those obtained by rotating the reflector, with the 

 cylinder stationary, are confirmed by those obtained with a stationary 

 reflector and a movable cylinder the latter method not having been 

 employed by Mr. Starke. 



In conclusion, the writer desires to express his great indebtedness to 

 the valuable assistance of Mr. J. C. M. Stanton and Mr. H. L. Tyson 

 Wolff in carrying out the above investigations. 



* < Eoy. Soc. Proc.,' vol. 63, pp. 434-5. 



