120 Mr. L. Simons on the Beta-Ray Emission from 



The case for and against the ring electron has been 

 presented in a discussion held at a meeting of the Physical 

 Society on October 25, 1918 *. 



Summary and Conclusion. 



A proof is given of a theorem due to S. B. McLaren, 

 according to which the angular momentum of a magneton of 

 any shape or dimensions about its axis of symmetry is 

 ^ m ~N e /27r, where N e is the number of tubes of electric induc- 

 tion terminating on the surface, and N m is the number of 

 tubes of magnetic induction passing through the aperture. 

 Combining this result with J. W. Nicholson's natural unit 

 of angular momentum, A/27T, where h is Planck's constant, 

 we find that h is equal to the product of the number of tubes 

 of magnetic induction and the number of tubes of electric 

 induction, or N m = A/e, where e is the electron charge. 



A further relation between h and e is given by Lewis and 

 Adams. This leads to a simple expression for the self- 

 inductance of the ring, which may be combined with Lord 

 Rayleigh's formula for the inductance of an anchor ring of 

 circular cross-section. By employing Webster's expression 

 for the mass of the Parson magneton and A. H. Compton's 

 estimate for the radius of the ring, it is possible to calculate 

 the most important numerical constants for the ring electron. 

 A table of these constants is given, from which it appears 

 that intense local magnetic fields must exist in the neigh- 

 bourhood of the magneton. 



VIII. The Beta-Ray Emission from Thin Films of the 

 Elements exposed to Rontgen Rays f. By Lewis Simons, 

 B.Sc. (London), Senior Lecturer in Physics in the University 

 of Cape Town J . 



[Plate III.] 



Introductory. 



THE emission of corpuscles from metal plates exposed to 

 Rontgen rays has been studied by Sadler § and Beatty || . 

 T\liiddington^[ coupled the results of these observers with 

 his own and showed that the maximum range, in air, of the 



* Proc. Phys. Soc. vol. xxxi. pp. 49-68 (1919). 



t The expenses of this research are partly covered by a Government 

 grant through the Research Committee of the Advisory Board of Science 

 and Industries of the Union -of South Africa. 



% Communicated by Prof. O. W. Richardson, F.R.S. 



§ Phil. Maa-. S er. 6," vol. xix. p. 337 (1910). 



!| Phil. Mao-. v ol. xx. p. 320 (1910). 



f Proc. Rov. Soc. A. vol. lxxxvi. p. 370 (1912]. 



