230 Mr Orange, On certain phenomena of the kathode region. 



the dark space of the other. The particles will lose kinetic 

 energy as they approach the second kathode, most of the loss 

 occurring very near the latter owing to the character of the field, 

 and they will tend to drift a little in the direction parallel to the 

 kathodes. They will not quite reach the second kathode since 

 they must have lost some energy by ionization en route ; they 

 may subsequently travel back towards the kathode of origin and 

 continue to swing across the interkathodic space, but always 

 trending laterally outwards. Finally, they will have travelled to 

 the right or left considerably and when their velocity is a minimum, 

 i.e. when near one of the kathodes, they will be borne out of the 

 interspace in a manner determined by the electrostatic field. 



As was stated above, the visible paths of the pencils indicate 

 the presence of free negative charge in the middle of the inter- 

 space, a view which can be supported as follows : 



For two reasons there is much ionization (and hence lumin- 

 osity) in the interspace. 



(1) The kathode rays are not as swift here as elsewhere 

 (since they start in the weaker field evidenced by the thickness of 

 the dark space), and 



(2) the kathode rays, and also some proportion of the 

 negative ions to which they give rise, oscillate about the median 

 plane, so that at any instant there is an exceptionally large amount 

 of ionization proceeding. 



The concentration of negative ions must be high in the neigh- 

 bourhood of the median plane and many of them doubtless travel 

 out along that plane and constitute the horizontal sheet of rays 

 seen in the photographs. 



In summary then : 



We regard the electrostatic field as being due mainly to three 

 things. 



(1) The actual charge on the kathodes ; the effect of this 

 cannot be great, since the covered supports of the kathodes produce 

 little or no visible effect. 



(2) The distribution of positive charge so that it is 

 especially abundant very near to the surfaces of the kathodes, as 

 assumed from Schuster's experiments, {loc. cit.) 



(3) An accumulation of negative charge about the median 

 plane of the interspace. This must be postulated, I think, to 

 account for the considerable divergence of the oblique ray sheets 

 and their peculiar curvature. 



The oblique sheets are regarded as the kathode rays arising 

 primarily from the kathodic interfaces and losing energy by 

 ionization of the gas as they travel backwards and forwards 

 between the kathodes. As long as the particles, in their surgings. 



