SENSATIONS IN TERMS OF LUMINOSITY. 273 



290 RS OS V 



(19) 100 = 40-53 + 58-28 + T19. 



294 RS GS V 



(20) 100 = 37-57 -f 59-08 4- 3'35. 



(XVII.) Determination oftlie Sensation Values in the Blue-Green. 



The next determinations were made with two slits, as before described ; one being 

 at SSN 245 and the other in the blue of different hues, with the following results. 

 The first one is shown in detail. Slits at SSNs 312 and 245. 



The frame was moved "9 division of the scale towards the red, which was 

 equivalent to placing the slits at SSNs 302 "4 and 241 '4 respectively, the back scale 

 being '4 of the front scale. 



Now the increase in red and consequent diminution in the green sensation at 241*4 

 is 4'54. 



245 



The proportion of RS to GS is therefore (see Equation (6) for 100) 



RS RS GS GS 



(69-60 + 4-54) to (30'40 4'54) or 74'14 to 25'86. 



The luminosity equation is 



241-4 208-4 W. 

 87 + 13 = 100. 

 From this we derive that 



308-4 RS GS V 



(21) 100 = 30-15 + 56-85 + 13. 



Slits at 245 and 320. 



The slit-holder was moved 5 of the back scale, which was equivalent to moving 

 each slit 2 units towards the red. The slits were, therefore, actually at 243 and 318. 

 The increase in red being T25 per cent, per unit of scale, at this point it became 

 72'1 per cent, and the green 2 7 '9 per cent. 

 The equation is 



243 318 W 

 92 + 8 = 100. 

 Hence 



318 RS GS V 

 (22) 100 = 26 + 53 + 21. 

 VOL. CXCIII. A. 2 N 



