NATURAL PHILOSOPHY. 143 



while pale pinks and greens were regarded as cloudy white, fine pink as 

 very pale blue, and crimson as blue; white red, ruddy pink, and brick red 

 were all yellows, and fine pink blue, with much yellow. Dark shades of 

 red, blue, or brown were considered as merely dark, no color being recog- 

 nized. 



The account of Dr. Dalton's own peculiarity of vision, by himself, offers 

 considerable interest. He says, speaking of flowers : " With respect to 

 colors that were white, yellow, or green, I readily assented to the appropriate 

 term; blue, purple, pink, and crimson appeared rather less distinguishable, 

 being, according to my idea, all referable to blue. I have often seriously 

 asked a person whether a flower was blue or pink, but was generally con- 

 sidered to be in jest." He goes on further to say, as the result of his 

 experience: "1st. In the solar spectrum three colors appear, yellow, blue, 

 and purple. The two former make a contrast; the two latter seem to differ 

 more in degree than in kind. 2d. Pink appears by daylight to be sky-blue 

 a little faded; by candle-light it assumes an orange or yellowish appearance, 

 which forms a strong contrast to blue. 3d. Crimson appears muddy blue 

 by day, and crimson woollen yarn is much the same as dark blue. 4th. lied 

 and scarlet have a more vivid and flaming appearance by candle-light than 

 by daylight" (owing, probably, to the quantity of yellow light thrown upon, 

 them). 



As anecdotes concerning this curious defect of color-vision, we may quote 

 also the following: "All crimsons appear to me (Dr. Dalton) to be chiefly 

 of dark blue, but many of them have a strong tinge of dark brown. I have 

 seen specimens of crimson claret and mud which were very nearly alike. 

 Crimson has a gra-ve appearance, being the reverse of every showy or 

 splendid color." Again: "The color of a florid complexion appears to me 

 that of a dull, opaque, blackish blue upon a white ground. Dilute black 

 ink upon white paper gives a color much resembling that of a florid com- 

 plexion. It has no resemblance to the color of blood." We have a detailed 

 account of the case of a young Swiss who did not perceive any great differ- 

 ence between the color of the leaf and that of the ripe fruit of the cherry, 

 and who confounded the color of a sea-green paper with the scarlet of a 

 riband placed close to it. The flower of the rose seemed to him greenish 

 blue, and the ash-gray color of quicklime light green. On a very careful 

 comparison of polarized light by the same individual, the blue, white, and 

 yellow were seen correctly, but the purple, lilac, and brown were confounded 

 with red and blue. There was in this case a remarkable difference noticed 

 according to the nature and quantity of light employed; and as the lad 

 seemed a remarkably favorable example of the defect, the following curious 

 experiment was tried. A human head was painted, and shown to the color- 

 blind person, the hair and eyebrows being white, the flesh brownish, the lips 

 and cheeks green. When asked what he thought of this head, the reply 

 was, that it appeared natural, but that the hair was covered with a nearly 

 white cap, and the carnation of the cheeks was that of a person heated by a 

 long walk. 



There is an interesting account in the Philosophical Transactions for 1859 

 (p. 32-5), which well illustrates the ideas entertained by persons in this con- 

 dition with regard to their own state. The author, Mr. W. Pole, a well- 

 known civil engineer, thus described his case : " I was about eight years 

 old, when the mistaking of a piece of red cloth for a green leaf betrayed the 

 existence of some peculiarity in my ideas of color; and as I grew older 



