22 THE POPULAR SCIENCE MONTHLY. 



tions. 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 {l>) being positive. Notice how widely differ- 

 ent 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 center 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 wii'e 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) positive, 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, while 

 in a high vacuum the position of the positive 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. 



