14 On Radiant Matter. 



rately exhausted bulb (A) with the induction-coil, and re- 

 taining the pole at one side (a) always negative, I will put 

 the positive wire successively to the other poles with which 

 the bulb is furnished. You see that as I change the 

 position of the positive pole, the line of violet light joining 

 the two poles changes, the electric current always choosing 

 the shortest path between the two poles, and moving about 

 the bulb as I alter the position of the wires. 



This, then, is the kind of phenomenon we get in ordinary 

 exhaustions. I will now try the same experiment with a bulb 

 (B) that is very highly exhausted, and as before, will make 

 the side pole (a') the negative, the top pole (6) being positive. 

 Notice how widely different is the appearance from that 

 shown by the last bulb. The negative pole is in the 

 form of a shallow cup. The molecular rays from the cup 

 cross in the centre of the bulb, and thence diverging fall on 

 the opposite side and produce a circular patch of green 

 phosphorescent light. As I turn the bulb round you will 

 all be able to see the green patch on the glass. Now observe, 

 I remove the positive wire from the top, and connect it with 

 the side pole (c). The green patch from the divergent negative 

 focus is there still . I now make the lowest pole (d) posi- 

 tive, and the green patch remains where it was at first, 

 unchanged in position or intensity. 



We have here another property of Radiant Matter. In the 

 low vacuum the position of the positive pole is of every 

 importance, whilst in a high vacuum the position of the posi- 

 tive pole scarcely matters at all ; the phenomena seem to 

 depend entirely on the negative pole. If the negative pole 

 points in the direction of the positive, all very well, but 

 if the negative pole is entirely in the opposite direction it 

 is of little consequence : the Radiant Matter darts all the 

 same in a straight line from the negative. 



If, instead of a flat disk, a hemi-cylinder is used for the 

 negative pole, the Matter still radiates normal to its surface. 

 The tube before you (Fig. 8) illustrates this property. It 

 contains, as a negative pole, a hemi-cylinder (a) of polished 

 aluminium. This is connected with a fine copper wire, 6, 

 ending at the platinum terminal, c. At the upper end of 

 the tube is another terminal, d. The induction-coil is con- 

 nected so that the hemi-cylinder is negative and the upper 

 pole positive, and when exhausted to a sufficient extent 

 the projection of the molecular rays to a focus is very 

 beautifully shown. The rays of Matter being driven from 

 the hemi-cylinder in a direction normal to its surface, come 



