342 Report of the Committee on Colour-Vision. 



want of promptness. If there is the slightest doubt we re-examine, 

 always testing- such cases with Holmgren's wools before finally 

 rejecting them. Naval cadets and engineer students have four 

 examinations in colour-perception before they are declared unfit. 



The conclusion in the case I referred to as totally colour-blind 

 must have been arrived at in the ordinary way by Holmgren's 

 wools, the flags and buntings. I may mention that if boys, when 

 sent to the training-ships from our Rendezvous, are suspected with 

 regard to their colour-perception, it is reported, and they are, 

 when on the ship, tested by night as well as day : by day 

 with the telescope up to, say, the distance of a mile, and at night- 

 time with the coloured lights at the full length of the ship. [The 

 Witness here exhibited a specimen of the Admiralty green glass, 

 as used in the lights, and explained with reference to it.] 



We never find anybody who can distinguish the Admiralty 

 green who cannot distinguish a greener green. Where candi- 

 dates persistently confuse red and green in the lantern, but sort 

 the wools correctly in using Holmgren's test, it is the fault of 

 the lantern not being sufficiently green. Speaking of colour- 

 blindness which is not congenital, I should say that all the naval 

 cadets to which I have referred were, as far as our registers 

 show, rejected for colour-blindness which was congenital, but I 

 should have difficulty in getting further information upon that 

 point. 



We have no records of men with normal vision among whom 

 colour-blindness has been brought on by disease. 



Naval officers are never examined after their appointment, 

 and, therefore, they might be suffering from tobacco amblyopia ; 

 but naval cadets and engineer students are not allowed to 

 smoke until they are eighteen years of age, and on the Britannia 

 they are, of course, constantly being examined with colours. 



When they have once been passed into the Service they would 

 not be examined again systematically ; but if there was any 

 suspicion as to colour perception, they would be examined by the 

 medical officer of their own ships, and invalided, and if found to 

 have defective colour- vision, be removed from the Service. 



There have been a few cases of blue-jackets who, upon offering 

 themselves for rating as signalmen, were rejected as colour-blind, 

 but upon closer examination it has been found to be due to defects 

 of the accommodation of the eye. 



This would be brought out in the following way: — Upon a 

 man being examined for signalman he would be required to read 

 hoists of 20 or 30 flags at once, and upon being asked by his 

 examiner what a flag was would answer " w " instead of " q," 

 and upon reference it would be found he mistook red for green. 

 This might be due to defective vision rather than defective 

 colour perception, but this would come out in examination at the 

 shorter ranges. 



All men are examined, as every man is a look-out man more or 

 less. All pass a course of musketry and gunnery instruction, 



