

Spectrum and the Primary Colour Sensations. 79 



curves in fig. 22 show all these classes excepting only that 

 ■for violet colour-blindness, for which type I have not jet 

 found a subject. 



For the purpose of comparison, I have brought together 

 the exact hues of the primary colours according to several 

 investigators whose experiments were conducted on the basis 

 of the trichromatic theory. With these are included the 

 colours selected by Hering for his theory of colour-vision, 

 and those determined for the same theory by the accurate 

 experiments of Baird *. 



Bed. Green. Blue. 

 jHelmholtz ... Carmine-red ; not in ~5Q fx to '54 /x. Ultramarine- 

 spectrum, blue. 



X6> T [G Purple-red; just out- *505ju. "470ju. 



side spectrum. 



Exner Red complementary to '508 /i. -475 /.t. 



•494 fi. (About -66 p.) 



Alle.v Between end of spec- "570 ix to "470 /u Violet, between 



truui and -66 //. - 420 /.t and end. 



Bed. Green. Yellow. Blue. 



Hering Purple-red; - 495 p. -5745^. '471^. 



non-spectral. 

 ■Baird Purple-red; "490 u. -570 fx. 460 p. 



non-spectral. 



There is no conflict necessarily arising between my own 

 fundamental hues for red and green and those of Helmholtz, 

 Konig, and Exner ; there is divergence in the case of violet. 

 But if it is at all justifiable for Helmholtz and the others to 

 differ in their green hues by nearly *06 fju, no exception need 

 be taken to my violet determination because it differs from 

 the others by an equal amount. 



In endeavouring to connect the transition points with 

 other colour-phenomena, I have found specially suggestive 

 the colour-sensation curves obtained by Abney and Watson, 

 fig. 23, and by Konig and Dieterici, fig. 24. On each of 

 *these figures I have indicated the transition points by short 

 vertical lines with wave-lengths attached. 



In the curves of Abney and Watson the transition points 

 X'660/a and X '470 ^ are practically at the ends of the 

 sensation curve for green ; and the remaining transition points 

 at X *420 fju and A, "570 \x are near the ends of the sensation curve 

 for blue. While the green and red sensation curves extend 

 to the wave-length X '43 yu,, yet their influence compared with 

 blue seems quite negligible on the more refrangible side or' 

 A'470/u,. The transition point at X '570 /a is also very close 



* J. W. Baird, "The Colour Sensitivity of the Peripheral Retina," 

 *Carnegie Institution, 1905. 



