470 



Mr. C. Lloyd Morgan. 



obtained by directly experimental metbods. That portion of the- 

 curve, for example, which lies between black and the luminosity point 

 for red may be compared with the curve for red on black, and similarly 

 the remaining portion of the curve with that for white on red. TTe- 

 have to deal with the parts of the graph blocked off by dotted lines in 

 fig. 4. For convenience of comparison these are in the following table- 

 converted into mid-point percentages. 



Mid-pom t Percen fa get. 





Luminosity 



Method 





method. 



of shading 



Yellow on black 



13-8 



13-5 



Orange on black 



Light blue on black 



18-6 



18-0 



19-7 



19-0 



Red on black 



23-6 



23-0 



Full blue on black . . . . 



29-5 



28-0 



White on full blue 



24-7 



25-0 





30-6 



30-0 



Orange on full blue 



354 



36-0 



Yellow on light blue . . 



39-1 



40-0 



Eed on full blue 



43-0 



44-0 



Fig. 4. 



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