The Constitution of Atoms. 281 



forces acting on an electron due to a beta particle at this close 

 range will greatly exceed the restoring forces due to the 

 other electrons in the atom which for weaker fields may make 

 the atom diamagnetic. In fact, there is no reason for sup- 

 posing that the effective susceptibility of the medium when 

 subjected to such highly intense magnetic pulses of very 

 short duration has any intimate relation to its susceptibility 

 iu steady and comparatively weak fields. It seems rather 

 that the problem must be treated as a statistical one of 

 encounters of a rapidly moving, electrically charged, magnetic 

 doublet with a random distribution of similar doublets at rest. 

 A preliminary investigation of this problem indicates, how- 

 ever, that the average motion of the beta ray should be 

 rather similar to its motion when passing through a medium 

 of uniform susceptibility. The above numerical discussion 

 is therefore of value as showing that it is not unreasonable 

 to expect a magnetic particle to induce. in the surrounding- 

 medium a magnetization of the magnitude required to account 

 for the observed helical paths. 



If the obvious explanation of these spiral tracks is the correct 

 one, their interpretation yields very valuable results. We 

 have seen that the beta ray seems to act as a tiny gyroscope 

 with a magnetic moment, which is capable of giving rise to 

 torques on other electrons of a duration corresponding to the 

 frequency of X-rays. The reaction, according to classical 

 dynamics, must result in mutational oscillations of the spinning- 

 beta particle. This obviously supplies a mechanism for the 

 production of high frequency radiation by a free electron, 

 which has been suggested by Webster to account for Doppler 

 effects at the target of an X-ray tube. The possibility that 

 the electrons are magnetic doublets is also of great impor- 

 tance in connexion with our ideas of the structure of the 

 atom and the nature of chemical combination. 



Cavendish Laboratory, 



Cambridge University. 

 August 16, 1920. 



XXIV. 1 lie Constitution of Atoms. By Professor Oeme 

 Masson, F.R.S., University of Melbourne *. 



SINCE it must now be conceded that all material atoms 

 are compounded of positive and negative electrical 

 atoms, it is surely time that each of these fundamental and 

 universal constituents were known by some distinctive 

 name. This compliment has been paid to the one, but not, 



* Communicated by Professor Sir E. Rutherford, F.B.S. 



