r 



DEDICATION: 



TO 

 THE HON. P. H. WATSON, 



WHOSE FRIENDSHIP HAS ENCOURAGED AND WHOSE PARTICIPATION HAS 

 GIVEN DOUBLE PLEASURE TO THE INVESTIGATIONS RECORDED 

 IN THESE PAGES ? THE TRUE FRIEND, AND THE LIB- 

 ERAL PATRON OF SCIENTIFIC EXPERI- 

 MENT, THIg LITTLE BOOK 

 IS DEDICATED 

 BY THE 



AUTHOR. 



