ACCIDENTS BY RAIL AND SEA. 1G3 



A color-bliud iudividual of the tj^pical kinds cannot distiugnish red 

 from green. This is an undoubted fact, easily explained by theory and 

 adequately proved by experience. All that he asserts about differences 

 between these colors is founded consequently upon conjecture. But this, 

 manner of perceiving signals is attended by great uncertainty, and he 

 who guesses correctly in this manner in a certain number of special 

 cases must infallibly guess wrong in some cases. This is a principle 

 which does not rest on a theory, but which has been confirmed by our 

 experience without an exception in an examination of more than two 

 hundred color-blind persons, and its evidence could be extended far 

 beyond the limits to which we are confined here, or, in other words, to 

 the majority of the cases of incomplete color-blindness. 



If a small amount of soot, smoke, vapor, ice, snow, etc., adhere to the 

 glass, the lantern shines less brightly. A lantern shines differently in. 

 ciear or foggy weather, etc. All this may give rise to mistakes. But, 

 on the other hand, the sensibility of the eye is very different according 

 to circumstances. The nervous organ of the eye may, like every other 

 part of the system, vary extremely in sensibility. The same light is to 

 the sound and rested eye stronger than to the weak and tired eye, etc. 

 But every modification of intensity of light is equivalent, to the color- 

 blind, to a change of color. All this proves how little reliance can be 

 placed upon the knowledge of signals acquired by the color-blind by 

 practice. 



III.— EEFORMS EELATING TO COLOK-BLINDNESS. 



As we have shown already, the tendency of color-blindness to conceal 

 itself wheresoever it occurs, in all classes of society, especially in the lower, 

 may be regarded as one of its most remarkable peculiarities. It is 

 necessary to add still another circumstance: one whose color-blindness 

 has been disclosed, and who is thus himself made aware of his defect, 

 and who has been, as is so commonly the case, a subject of ridicule 

 to his acquaintances, is generally more than ever eager to conceal his 

 infirmity. The result of this is, in spite of all that has been written on 

 color-blindness, this affection of the sight, far from being recognised 

 as a fact belonging to every-day life, has been and still is considered by 

 the public as a legend about which anything desired could be believed. 

 The idea, at least, usually formed with regard to its frequency and prac- 

 tical importance, is far from corresponding with the reality. It is diffi- 

 cult to accustom one's self to the idea of the necessity of refusing to 

 a number of persons admission to a career which would afford them 

 means of subsistence, and, what is worse, to discharge from their present 

 position those who have performed their duties in an irreproachable 

 manner, and which have been to them and their families a legitimate 

 source of income. 



Prompted by a just regard for the good of man, it is asked whether 



