238 



THE ROYAL SOCIETY OF CANADA 



McCluug of the same department for valuable discussions and kind 

 interest shown. The method employed is also due to Professor 

 Allen. 



Department of Physics, 



University of Manitoba, 

 Winnipeg, Manitoba. 



Note. — A most comprehensive study conducted by Dr. 11. E. Ives and several 

 assistants, has lately appeared in a series of five papers (Phil. Mag., Vol. 24, 1912, 

 pp. 149-188; 352-370; 744-751; 845-863) under the general title "Studies in the 

 Photometry of Lights of Different Colors." Because of the fact that the writing of 

 the present paper was completed before the publication of Dr. Ives papers no 

 reference has been made to them. I should like to point out however, that, though 

 in obtaining the Luminosity Curve for the Spectrum, I was dependent upon other 

 means to get a spectrum of uniform luminosity, the human eye when undisturbed 

 by the presence of a second color is capable of distinguishing changes in luminosity 

 to a very fine and uniform degree of sensitiveness as is shown by the smoothness of 

 his luminosity curve. 



TABLE I. 



