Vision of Colours of Varying Intensity. 



89 



figure. This confirms and extends similar results obtained 

 by Konig*. 



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My original intention was only to obtain the curves for the 

 persistence of vision which are shown in fig. 1. Consideration 

 of the data obtained, however, showed that they could be 

 utilized in the various ways discussed in this paper. These 

 are largely the confirmation, as well as the extension, of the 

 work of other investigators, which is always desirable, 

 especially when different methods of experimentation are 

 used. This confirmation has an additional advantage, since 

 it shows how completely reliable is the method of the critical 

 frequency of flicker, or persistence of vision, as a means of 

 investigating the phenomena of colour vision. 



* Konig, Gesammelte Abhandlungen, p. 144; also ' Colour Vision,' 

 Parsons, p. 59. 



