234 



Sir David Salomons, Bart. 



[June 21, 



Experiment 1. 



A plain tube of large diameter with aluminium brush electrodes at 

 the ends is employed. (See fig. 1.) On passing an electric dis- 

 charge, with very slow alternations, at first the tube appears dark, 

 and the speed of the alternator then being slightly increased, the 

 light just becomes visible within the tube, and there is seen a few 

 bright bands with dark spaces intervening. These bands are convex, 

 the convexity being towards the centre of the tube in all cases. The 

 bands do not extend to the centre of the tube, consequently the con- 

 vex sides of the bands at each end of the tube face one another, and 

 do not meet in the centre of the tube. The motor is then stopped, 

 and the falling light in the tube is carefully watched. It can then 

 be noticed that the moment before the current dies out, and the 

 bands disappear, one or two more appear nearer to the centre. On 

 the other hand, if the current is increased the bands are driven to- 

 wards the electrodes until they disappear altogether. The tube is 

 then simply lighted throughout. 



The experiment is now repeated when a current is adjusted to pro- 

 duce the bands, and the centre of the tube is placed to earth by 

 resting the hand upon it or in any other convenient manner, when it 



Fia. 1. 



Fia. IA. 



