Some Experiments ivith Cathode Bays. 



87 



remaining portion of the ring- 

 shaped section of the cone 

 to contract correspondingly, 

 without, however, altering 

 its diameter. 



In order to further investi- 

 gate the matter another tube 

 was made, as shown in fig. 10, 

 in which the concave cathode 

 was complete ; but the in- 

 terior of the tube was fur- 

 nished with a small movable 

 piece of aluminium, A, which 

 by shaking could be moved 

 up and down the tube be- 

 tween the cathode C, and 

 an ti- cathode B, and which, 

 while not quite reaching the 

 centre of the tube, would fill 

 up very nearly one quarter of 

 the circular sectional area of 

 the latter. 



With this arrangement of 

 tube, with the aluminium 

 obstacle placed just at the 

 focus, as shown in fig. 11, 

 the point of the obstacle just 

 missing the cathode rays, a 

 complete ring was formed on 

 the carbon anti-cathode. On 

 moving the obstacle slightly 

 into the divergent cone, ex- 

 actly one quarter of the ring 

 on the anti-cathode failed to 

 appear, as shown in fig. 12, 

 and on the obstacle being 

 further moved in the same 

 direction the result was not 

 altered, as shown in fig. 13. 



As in each of the latter 

 two cases there was no dis- 

 placement of the gap in the 

 ring, the above showed that 

 there is no rotation of the 

 divergent cathode cone. 



I 



g 2 



