

THE WAVE THEORY OF LIGHT. 315 



finitude is incomprehensible, the infinite in the 

 universe is comprehensible. Now apply a little 

 logic to this. Is the negation of infinitude in- 

 comprehensible ? What would you think of a 

 universe in which you could travel one, ten, or 

 a thousand miles, or even to California, and then 

 find it come to an end ? Can you suppose an 

 end of matter or an end of space ? The idea is 

 incomprehensible. Even if you were to go millions 

 and millions of miles the idea of coming to an 



I end is incomprehensible. You can understand 

 one thousand per second as easily as you can 

 understand one per second. You can go from 

 one to ten, and ten times ten and then to a 

 thousand without taxing your understanding, 

 and then you can go on to a thousand million 

 and a million million. You can all understand it. 

 Now 400 million million vibrations per second 



tis the kind of thing that exists as a factor in the 

 illumination by red light. Violet light, after what 

 we have seen and have had illustrated by that 

 curve (Fig. 47), I need not tell you corresponds 

 to vibrations of about 800 million million per 



