Discharge in a Transverse Magnetic Field. 59 



Curve VT. re [» resents the relation between these quantities 

 under similar circumstances with the ring as cathode. 



These curves correspond to the series of discharges 

 typically represented by figs. 3 and 4. The pressures to 

 which these figures actually relate are, however, com- 

 paratively low. 



Throughout this series of changes ot' pressure, the rotatory 

 stage is absent. 



50 

 -1 5 



•10 

 35 





Fig. 20. Curve 



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-5 I 1-5 2 2-5 3 35 4 1;§ 

 > P. D. Spark length in nj.io. 



23. In fig. 21, curve VII. represents changes in P.D. with 

 pressure between the electrodes of the same tube with disk 

 as the cathode, the spark-length of the induction-coil in this 

 case beino- 29 mm. in atmospheric air. It corresponds to 

 the series of discharges typified by figs. 1 and 2. 



It will be observed that the latter includes a stage at 

 which discharge has, during a certain range of pressure, the 

 appearance of a band, and that there is rotation, only when 

 this state is reached, under th 

 force. 



influence of a radial magnetic 



