Dr. R. D. Kleeman on 5 Rays. 201 



a particle enters and leaves a metal surface at an angle of 

 45°, the asymmetry in the number of electrons given off would 

 be about one half that when the angle is equal to 90°. Such 

 an arrangement thus decreases the asymmetry. Further, it is 

 known that the number of ions or 8 rays made along the 

 path of the a particle increases as the velocity of the a par* 

 tide decreases. Thus the number of 8 rays produced in the 

 surface layer of the electrode where the a particles emerge 

 is less than in the layer of the same thickness where it enters. 

 This produces an asymmetry in the opposite direction to that 

 which would be produced if the electrons ejected have a 

 component of motion in the same direction as the motion of 

 the a particle ; and may thus largely eliminate the asymmetry 

 due to the latter cause. The foregoing effects in conjunction 

 with the volta effect and other disturbing causes may render 

 the asymmetry uncertain in magnitude and sign* 



It should be noticed that the ejected electron must have a 

 velocity sufficient to carry it out of the sphere of influence 

 of the positively charged parent molecule, otherwise the two 

 will at once combine again s If its velocity is zero ;when out 

 of the influence of the parent molecule^ practically no 

 asymmetry w r ould exist in the number of electrons given off 

 from the incident and emergent surfaces of the electrodes 

 when a steady state has been reached, for the electrons could 

 reach the surface by diffusion only in each case. But the 

 collision leak would show an asymmetry in the way explained* 



It appears, therefore, that more reliance must be placed 

 on what happens in the gas between the electrodes than 

 what happens on their surfaces. I maintain, therefore, that 

 my experiments indicate that the electron ejected by an 

 a particle from a molecule has a component of motion in the 

 same direction as the motion of the a particle. There does 

 not seem to be an alternative explanation of the experimental 

 results. If they are due to an asymmetry in the number of 

 electrons from the metal surfaces, they indicate the same 

 property. If they are due to an asymmetry in the number of 

 positive ions given off by the metal surfaces, they would 

 again indicate the same property. The positive part of the 

 molecule on being ionized would, in this case, be given a 

 motion in the opposite direction to the motion of the a par* 

 tide. But this is equivalent to giving the electron a motion 

 in the same direction as the motion of the a particle. 



Yours faithfully, 



R s D* Kleeman, 



