1890.] on Colour-Vision and Colour- Blindness, 129 



boys and men of the labouring classes. Many, wbo can see colours 

 perfectly, and who would never be in the least danger of mistaking a 

 railway signal, are quite unable to name colours or to describe, them ; 

 and they are sometimes unable to perceive, for want of education of a 

 faculty which they notwithstanding possess, anything like fine shades 

 of difference. Mr. Gladstone once published a paper on the scanty 

 and uncertain colour-nomenclature of the Homeric poems ; and he 

 might have found very similar examples among his own contemporaries 

 and in his own country. I Lave lately heard a description of a pattern 

 card of coloured silks, issued by a Lyons manufacturer, which contains 

 samples of two thousand different colours, each with its more or less 

 appropriate name. There is here a larger colour-vocabulary than the 

 entire vocabulary, for the expression of all his knowledge and of all 

 his ideas, w^hich is possessed by an average engine-driver or fireman; 

 and, just as most of us would be ignorant of the names of the immense 

 majority of the colours displayed on that card, so hundreds of men 

 and boys among the labouring classes, especially in large towns, 

 where the opportunities of education by the colours of flowers and 

 insects are very limited, are ignorant of the names of colours which 

 persons of ordinary cultivation mention constantly in their daily talk, 

 and expect their children to pick uj) and to understand unconsciously. 

 It is among people thus ignorant that the officials of the Board of 

 Trade, and of railways, have been most successful in finding their 

 supposed colour-blind persons ; and these persons, who would never 

 have been pronounced colour-blind by an expert, have been able, as 

 soon as they have paid a little attention to the observation and naming 

 of colour, to pass an official examination triumphantly. The sense of 

 colour presents many analogies to that of hearing. Some people can 

 hear a higher or a lower note than others, the difference depending 

 upon structure, and being incapable of alteration. No one who can- 

 not hear a note of a certain pitch can ever be trained to do so ; but, 

 within the original auditory limits of each individual, the sense of 

 hearing may be greatly improved by cultivation. In like manner, a 

 person who is blind to red or green must remain so ; but one whose 

 colour-sense is merely undeveloped by want of cultivation may have 

 its acuteness for fine differences very considerably increased. 



In order to test colour- vision for railway and marine purposes, 

 the first suggestion which would occur to many people would be to 

 employ as objects the flags and signal lanterns which are used in 

 actual working. I have heard apparently sensible people use, with 

 reference to such a procedure, the phrase upon which Faraday was 

 wont to pour ridicule, and to say that the fitness of the suggested 

 method " stands to reason." To be effectual, such a test must be 

 applied in different states of atmosphere, with coloured glasses of 

 various tints, with various degrees of illumination, and with the 

 objects at various distances ; so that much time would be required in 

 order to exhaust all the conditions under which railway signals may 

 present themselves. This being done, the examinee must be either 



Vol XIII. (No. 84.) k 



