198 COLOR BLINDNESS. 



tailor who could see in tbe rainbow but two tints, namely, yellow and 

 bright blue. Black appeared to him in general, gTeen, sometimes crim- 

 son — light blue appeared like dark blue, crimson, or black — green was con- 

 founded with black and brown — carmine, red, lake, and crimson with blue. 



But the most interesting case of this kind, is that of the celebrated 

 chemical philosopher, Dr. Dalton, of England. He published an account 

 of his own case and that of several others, in the Transactions of the 

 Manchester Society, in 1794. Of the seven colors of the rainbow, he 

 could distinguish but two, yellow and blue ; oi' at most, three, yellow, 

 blue, and jsurple. He saw no difference between red and green; so 

 that he thought the color of a laurel leaf the same as that of a stick of 

 red sealing-wax. A story is told of his having, on one occasion, appeared 

 at the quaker meeting, of which he was a member, in the usual drab 

 coat and small-clothes of the sect, with a pair of flaming red-colored 

 stockings to match. Yv'hatever may be the truth in reference to this 

 story, we have the assertion of Professor Whewell, that when Dr. Dalton 

 was asked with what he would compare the scarlet gown with which he 

 had been invested by the university, he pointed to the trees, and declared 

 that he perceived no difference between the color of his robe and that Of 

 their foliage. Dr. Dalton found nearly twenty persons possessed of the 

 same peculiarity of vision as himself; and among the number, the cele- 

 brated metaphysician, Dugald Stewart, who could not distinguish a 

 crimson fruit, like the Siberian crab, from the leaves of the tree on which 

 it grew, otherwise than by the difference in its form. 



On account of the prominence which Mr. Dalton's publication gave this 

 defect of vision, the continental philosophers gaveit the name of Da/toJi«sm. 

 To this name, however, several British writers have strongly objected. If 

 this system of names were once allowed, say they, there is no telling where 

 it would stop, the names of celebrated men would be connected, not with 

 their superior gifts or achievements, but with the personal defects which 

 distinguish them from their more favoured but less meritorious cotempo- 

 raries. Professor Whewell proposed the term Idiopts, signifying peculi- 

 arity of vision ; but to this name Sir Da vid Brewster properly objected, that 

 the important consonant p would be very apt to be omitted in ordinary pro- 

 nunciation, and so the last state of theldiopt would be worse than the first. 

 The name colorhlindness, suggested by Sir David, although not in all 

 cases free from objection, is perhaps better than any we have seen proposed. 



It has already been stated that the number of persons affected with 

 color-blindness, is much more considerable than is generally imagined 

 They are often themselves ignorant of their imperfection of vision, i)ar- 

 ticularly when it is restricted to the want of power to discriminate 

 between colors nearly related to each other. Professor Seebeck found 

 five cases among the forty boys who composed the two upper classes of a 

 gymnasium of Berlin. Professor Prevost, of Geneva, stated that they 

 amounted to one in twenty ; and Professor Wartmann does not think this 

 estimate much exaggerated. 



Observations on this peculiarity of vision have as yet been confined^ 



