298 Report of the Committee on Colour- Vision. 



stress on this point, as, if it were required from the examiner 

 that he should specify what would be the nature of a mistake 

 that an examinee would be likely to make, it would open the 

 door to controversy, and thus defeat the ends for which an 

 examination is instituted. What should be required of the 

 examiner is merely a statement that the candidate has either 

 passed or failed in the examination. In cases of failure, where 

 the candidate is under the impression that a mistake has been 

 made, an appeal to some properly appointed expert should be 

 allowed, and his decision should be final. 

 Tests recom- The Committee have carefully considered the question as 

 mended by to what tests should be recommended for general adoption on 

 the Com- railways and for the marine service. 



mittee. They are of opinion that tests which involve the naming- of 



colours should be avoided in deciding the question of colour- 

 blindness. Failure to satisfy these tests may be due to colour- 

 ignorance, and lead to the rejection of persons who are not really 

 colour-blind. A candidate who fails should be informed to what 

 cause his failure is due, whether to colour-blindness or to colour- 

 ignorance, with a view to subsequent re-examination in the latter 

 case. On the other hand, if the objects which the examinee is 

 required to name are few in number and accessible to the public, 

 since the chances are that no two of them are exactly alike 

 even to a colour-blind person, he might be instructed as to the 

 names which he is expected to give them, and thereby persons 

 who are really and seriously colour-blind might be passed by the 

 examiner as being free from any defect. Besides trustworthi- 

 ness, the tests should be adapted for the examination of large 

 bodies of men, and, provided efficiency be not sacrificed, they should 

 be of an inexpensive nature. After practical trials, and also 

 from theoretical considerations, the Committee are of opinion that 

 the simplest efficient test is the wool-test of Holmgren, applied 

 either in the form which Holmgren himself recommends, or in 

 that of Jeaffreson, which is based on precisely the same principles. 

 Holmgren's A full description of Holmgren's test, and of the proper 

 te - 8t * methods of applying it, extracted from Holmgren's work on the 



subject, is given in Appendix III, page 375. 



It is most important that the standard test-colours should be 

 of a proper character both as to hue and also as to dilution with 

 white, the efficiency of the test depending almost entirely on a 

 proper selection. The Committee recommend that sealed patterns 

 of all three test-colours should be kept by some central authority 

 — such as the Board of Trade ; and that every set of test- wools 

 should be officially passed as fulfilling the necessary conditions 

 as to these standard colours, and also as to the sufficiency and 

 variety of confusion colours. 



The standard test-colours which have been approved by Pro- 

 fessor Holmgren have been referred to the spectrum. The first 

 standard is a light green colour, which can be matched with a green 

 in the spectrum (A. 5660), when 40 per cent, of white is added 



