28 MEMOIR OF DR. DALTON, AND 



" I found that persons in general distinguish six kinds of 

 colour in the solar image ; namely, red, orange, yellow, 

 green, blue, and purple. To me it is quite otherwise; I 

 see only two, or at most three, distinctions; these I should 

 call yellow and blue, or yellow, blue, and purple. * * * * 

 My yellow comprehends the red, orange, yellow, and green 

 of others, and my blue and purple coincide with theirs." 



He sums up the peculiarities of the vision of himself and 

 others who have been found similarily affected thus; p. 40. 



"1. In the solar spectrum three colours appear — yellow, 

 blue, and purple. The two former make a contrast ; the two 

 latter seem to differ more in degree than in kind. 



2. Pink appears, by day light, to be sky-blue a little 

 faded; by candle light it assumes an orange or yellowish 

 appearance, which forms a strong contrast to blue. 



3. Crimson appears a muddy blue by day ; and crimson 

 woollen yarn is much the same as dark blue. 



4. Red and scarlet have a more vivid and flaming appear- 

 ance by candle light than by day light. 



5. There is not much difference in colour between a stick 

 of red sealing wax and grass, by day. 



6. Dark green woollen cloth seems a muddy red, much 

 darker than grass, and of a very different colour. 



7. The colour of a florid complexion is dusky blue. 



8. Coats, gowns, &c., appear to us frequently to be badly 

 matched with linings, when others say they are not. On the 

 other hand, we should match crimsons with claret or mud ; 

 pinks with light blues ; browns with reds ; and drabs with 

 greens. 



9. In all points where we differ from other persons, the 

 difference is much less by candle light than by day light." 



He found several persons having the same peculiarity of 

 vision, and says (p. 43i), " It appears, therefore, almost 

 beyond a doubt, that one of the humours of my eye, and of 



