][890.1 on Colour-Vision and Colour- Blindness. 125 



blindness is very rare, the vast majority of defective eyes are red or 

 green blind. These persons see violet and yellow as the normal- 

 eyed and they naturally apply these colour-names correctly. When, 

 therefore, they fail in red or green, a casual observer attributes it to 

 simple carelessness— hence a very ready avoidance of detection. It 

 does not seem possible that any one who sees so much correctly, and 

 whose ideas of colour so correspond with our own, cannot be ecLually 

 correct throughout, if they will but take the pains to notice and 



When the colour-blind are placed in positions which compel them 

 to select colours for themselves or others, or when, as sometimes 

 happens they are not sensitive with regard to their defect, but rather 

 find amusement in the astonishment which it produces among the 

 colour-seeing, the results which occasionally follow are apt to be 

 curious. They have often been rendered still more curious, by having 

 been the unconscious work of members of the Society of Friends. 

 Colour-blindness is a structural peculiarity, constituting what may be 

 called a variety of the human race ; and, like other varieties, it is 

 liable to be handed down to posterity. Hence, if the variety occurs 

 in a person belonging to a community which is small by comparison 

 with the nation, and among whose members there is frequent inter- 

 marriage, it has an increased probability of being reproduced ; and 

 thus, while many of the best known of the early examples of colour- 

 blindness, including that of Dalton himself, were furnished by the 

 Society of Friends, the examinations of large numbers of scholars 

 and others, conducted during the last few years, have shown that, 

 in this country, colour-blindness is more common among Jews than 

 among the general population. The Jews have no peculiarities of 

 costume ; but the spectacle, which has more than once been witnessed, 

 of a venerable Quaker who had clothed himself in bright green or in 

 vivid scarlet, could scarcely fail to excite the derision of the unre- 

 flecting. Time does not allow me to relate the many errors of the 

 colour-blind which have been recorded; but there is an instance of a 

 clerk in a Government office, whose duty it was to tick certain entries, 

 in relation to their subject-matter, with ink of one or of^ another 

 colour, and whose accuracy was dependent upon the order in which 

 his ink-bottles were ranged in front of him. This order having been 

 accidentally disturbed, great confusion was produced by his mistakes, 

 and it was a long time before these were satisfactorily accounted for. 

 An ofificial of the Prussian Post Office, again, who was accustomed to 

 sell stamps of different values and colours, was frequently wrong in 

 his cash, his errors being as often against himself as in his favour, 

 so as to exclude any suspicion of dishonesty. His seeming careless- 

 ness was at last explained by the discovery of his colour-blindness, 

 and he was relieved of a duty which it was impossible for him to 

 discharge without falling into error. 



The colour-mistakes of former years were, however, of little 

 moment when compared with those now liable to be committed by 



