180 Mr. A. A. C. Swinton. The Effects of a strong 



bottom of the tube, a very bright cone of blue luminescence with a 

 still brighter whitish blue core, made its appearance. When under 

 these conditions the tube was slightly moved sideways, the bright 

 spot at the apex of the cone, and the cone itself moved, the spot and 

 apex always maintaining a position exactly over the centre of the 

 magnet pole. At the same time the minor blue luminescence pro- 

 ceeding from the anode terminal, due probably to the " make " 

 current of the Ruhmkorff coil, was bent downwards towards the 

 magnet as shown, and deflected sideways one way or another accord- 

 ing to the polarity of the magnet, which polarity, however, did not 

 affect in any way the vertical cathode stream. The internal resist- 

 ance of the tube, as measured by an alternative spark gap on the 

 Buhmkorff coil, was also found to be very greatly diminished while 

 the magnet was excited. With the magnet not excited, the alterna- 

 tive spark would leap from 1^ to If inches, while, when the magnet 

 was excited, the gap had to be reduced to about j- inch before the 

 sparks would pass. As soon as the current from the magnet was cut 

 off, the appearance of the tube immediately reverted to what is 

 shown in fig. 1, and its internal resistance increased to what it had 

 been before. 



