430 Molecular Physics in High Vacua. [June, 
may be neglected. This line may be called the character- 
istic line of alumina. 
I now pass on to another faCt connected with this negative 
discharge. Here is a tube (Fig. 12) with a negative pole ( a , b) 
in the form of a hemi-cylinder, similar to the one you have 
already seen (Fig. 3), but in this case I receive the rays on a 
phosphorescent screen (c, d). See how brilliantly the lines 
of discharge shine out, and how intensely the focal point is 
illuminated ; it lights the whole table. Now I bring a small 
magnet near, and move it to and fro ; the rays obey the 
magnetic force, and the focus bends one way and the other 
as the magnet passes it. I can show this magnetic aCtion 
a little more definitely. Here is a long glass tube (Fig. 13), 
Fig. 13. 
very highly exhausted, with a negative pole at one end (a) 
and a long phosphorescent screen ( b , c) down the centre of the 
tube. In front of the negative pole is a plate of mica (b,d) with 
a hole (e) in it, and the result is that when I turn on the cur- 
rent, a line of phosphorescent light ( e,f ) is projected along the 
Fig. 14. 
whole length of the tube. I now place beneath the tube a 
powerful horseshoe magnet : see how the line of light 
becomes curved under the magnetic influence (e, g), waving 
