58 Dr. W. Pole on Colour-Blindness, 



The most suitable constants were found to be, in round 

 numbers, 



= 0-80. R- 0-35 . G + 0-55 .V, 



,y = 0-26.R + 0'35 . G + 0'39 .V, 



£ = 0-25 . R + 0'125 . G + 0-625 . V, 



where R, G, and V represent the quantities of each elemental 

 colour in a given spectral hue. 



To carry out the calculations, an immense number of obser- 

 vations were collected on the various spectral colours (some 

 50 on each hue), determining the proportions of R, G, and Y 

 in each colour. For example : at w.l. 520, the green hue 

 was found to be made up of 



4-62 of R + 8'45 of G+ 1-10 of V; 



then, applying the above equations to these figures, the pro- 

 portions of the three fundamental colours contained in this 

 hue of the spectrum were found to be 



1-37 of + 4-51 of .y + 2-90 of z. 



Or in 100 parts of the green, 



15 of + 51 of ?/ + 34 of 2. 



This being done for many points along the spectrum, and 

 the comparisons being satisfactory, the fundamental colours 

 can be laid down in a triangle, and their relations with the 

 spectrum shown in a geometrical form. The results will be 

 found in the tables on pages 454 and 455 and in the diagram 

 on page 457, 



The three newly-found fundamental colours are, generally 

 speaking, red, green, and blue ; but all very much more 

 highly saturated than anything in the spectrum. 



The Red, 0, is a highly saturated carmine-red, more tending 

 to blue than the extreme red of the spectrum. 



The Green, y, is a yellow-green about w.l. 560, somewhat 

 greener than the complement to violet, and nearly corre- 

 sponding to the green of vegetation. 



The Blue, z, is about w.l. 482, corresponding to ultra- 

 marine. 



The author states that the fundamental red and blue cor- 

 respond with Hering's anticipations ( Vermutliungen) ; and I 

 may be allowed to say that the former agrees with my deter- 

 mination of my own wanting colour in 1856, before any 

 one suspected the existence of an extra- spectral fundamental. 



The following short table, which I have made out from the 

 diagrams, tables, and formulae, will show, in a simple manner, 



