696 COLOR-VISION ANO COI.OR-BLINDNESS 



Wlicii the oolrM-blind are i)laci'(l in positions ^vllicll coinpel tliem to 

 select colors for themselves and others, or when as sometimes happens, 

 they are not sensitive with rejiiird to their (h'lcct, hnt rather lind 

 amnsement in the astonishment which it prodnces among the color- 

 seeing, the results which occasionally follow are apt to be curious. 

 Tiiey have often been rendered still more (jurions, by having been the 

 unconscious work of members of the Society of Friends. Color-blind- 

 ness 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 i)erson belonging 

 1o a conununity which is small by comparison with the nation, and 

 among whose members there is frequent inter- marriage, it has an in- 

 creased i)robability of being reproduced; and thus, while njany of the 

 l)est known of the early examples of color bindness, in; lading that of 

 Dalton himself, were furnished by the Society of Friends, the examina- 

 tions of large numbers of scholars and others, conducted during the last 

 few years have shown that in this country, color blindness is more com- 

 mon 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 him- 

 self in bright green or vivid scarlet, could scarcely fail toexcite the de- 

 rision of the unreHecting. Time does not allow me to relate the many 

 errors of the color-blind which have been recorded ; but there is an in- 

 stance of a clerk in a Government office, whose duty it was to check cer 

 tain entries, in relation to their subject-matter, with ink of one or of an- 

 ot her color, and whose accuracj' was dependent uj)on 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 official of the Prussian post-oftice, again, who was accustomed to 

 sell stamps of different values and colors, was frequently wrong in his 

 easii, his errors being as oiten against himself as in his favor, so as to 

 exvlude any suspicion of dishonesty, liis seeming carelessness was at 

 last explained by the discovery of his color-blindness, and he was re- 

 lieved of a duty which it was impossible for him to discharge without 

 falling into error. 



The color mistakes of former years were however of little moment 

 when compared with those now liable to be committed by engine driv- 

 ers and mariners. The avoidance of collisions at sea and on railways 

 depends largely on the power promptly to recognize the colors of sig- 

 nals; and the colors most available for signaling purposes are red and 

 green, or precisely those between whi(;h the sutierers from the two 

 most common forms of color-blindness are unable with any certainty 

 to discriminate. About 13 years ago there was a serious railway acci- 

 dent in Sweden, and in the investigation subsequent to this accident, 

 there were some remarkable discrepancies in the evidence given with 



