208 



Sir William Thomson 



[Feb. 2, 



a long time ago by Professor Stotes ; and year after year I have 

 begged him to publish it, but he has not done so, and so I have asked 



Fig. 10. 





I 

 I 

 I 



/ 



-f 



4 



^-^ 



41) 



Diagram showing the diflferent amplitudes of vibration of a row of particles 

 oscillating in a period less than their least wave-period. 



him to allow me to speak of it to-night. It is a dynamical explanation 

 of that wonderful phenomenon called fluorescence or phosphorescence. 



