Accidental and Complementary Colours. 



211 



to account for most of the phenomena of accidental and 

 complementary colours ; especially, as I cannot admit with 

 him that the accidental colour of red is blue; of violet 

 yellow, &;c. (Records, vol. ii. p. 110, et seq.) The follow- 

 ing Table will show that with seven primary colours and 

 their complements, red, yellow, and blue, are in each case 

 afforded. 



Table of the Seven Primary Colours with their Com- 

 plements and Composition. 



I shall now proceed to notice other cases of accidental 

 colours and to offer an explanation, reserving for the close 

 of the next paper a general and brief analysis of my theory. 



7. *' If we place a bright red wafer upon a sheet of white 

 paper and fix the eye steadily upon a mark in the centre of 

 it, then if we turn the eye upon the white paper we shall 

 see a circular spot of blueish-green light, of the same size 

 as the wafer." — {Brewster's Optics, p. 304.) This effect is 

 explained by supposing the sensibility of the eye to red 

 light to be diminished, "and, consequently, that when the 

 eye is turned from the red wafer to the white paper, the 

 deadened portion of the retina will be insensible to the red 

 rays which form part of the white light from the paper, 

 and, consequently, will see the paper of that colour which 

 arises from all the rays in the white light of the paper but 

 the red ; that is, of a blueish-green colour, which is, there- 

 fore, the true complementary colour of the red wafer." — 

 Brewster s Optics, p. 305. 



I have, in a previous paper, objected to those experiments 

 which fatigue the eye, because, under such circumstances, 

 the result is an unnatural one. Accidental colours can be 

 abundantly seen together with the primary colour, naturally 

 and easily ; and upon such data a theory ought, I conceive, 

 to be founded. I object to the explanation which imputes 



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