1844-54. LABORIOUS INQUIRY. 335 



lays stress on their due appreciation of colour, testing them as 

 recommended by Dr. Wilson ; and there is little doubt that, as 

 the importance of the subject is more generally recognised, it 

 will receive the attention it merits. In navigation, Dr. Wilson 

 urges the employment of night signals which the colour-blind 

 cannot mistake, the Admiralty system being fraught with un- 

 suspected danger to all who trust in it. 



"As facts accumulated, the interest of the subject presented 

 itself more and more forcibly, and Dr. Wilson felt, in 1855, that 

 the time had arrived when the results of his researches should 

 be presented to the profession and the public. An extended 

 analysis of this work would be out of place in a biography, and 

 it will be sufficient to mention some of its leading points. 



" The first thing that strikes us is the amount of labour 

 bestowed upon the inquiry ; in 1852-53 alone, Dr. Wilson care- 

 fully examined 1154 persons with reference to colour-blindness, 

 and subsequently a further large number ; it may be confidently 

 asserted that no one had previously extended the investigation 

 so widely, and the results are commensurate. 



" It is somewhat startling to find that Dr. Wilson arrived at 

 the conclusion, that one in every twenty persons has an imper- 

 fect appreciation of colour, and that the number who are 

 colour-blind in so marked a degree as to mistake red for green, 

 brown for green, and occasionally even red for black, is one in 

 fifty. Dr. Wilson's researches fully established the hereditary 

 character of colour-blindness, which clings in a remarkable 

 degree to certain families ; he observed, that so far as tints are 

 concerned, the colour-blind have as nice discernment as others ; 

 it is proper to mention that Sir John Herschel and others 

 entertain doubts as to whether colour-blindness is really as 

 common as stated by Dr. Wilson ; the question may be re- 

 garded as yet open. 1 To a person with perfect vision it is 

 startling, and almost verges on the ludicrous, to see another 

 apparently equally gifted, gravely sorting scarlet and red and 

 green worsteds as shades of one and the same colour ; declaring 

 that a stick of red sealing-wax was not to be distinguished on 



i See ' Statistics of Colour-Blindness' in c Report of the British Asociation for 

 1859,' p. 228. 



