37° 



NA rURE 



[January 27, 1910 



days. But from the point of view of tlie Board of 

 Trade and of the mercantile marine such caprice 

 must be ver}- dangerous. The motion ^vas by leave 

 withdrawn. 



Since this debate in the House of Lords the case of 

 Mr. John Trattles has assumed greater importance, 

 and it will be well to recount briefly its history and 

 the chief features which it presents. In Februarv, 

 1904, Mr. Trattles was examined for his certificate as 

 second mate ; he passed the colour-vision test, and was 

 granted his certificate. In July, 1905., he went up for 

 examination as first mate, and failed in the colour- 

 vision test. He appealed, and was specially examined 

 by Sir William Abney and Captain Harvey,' and again 

 failed. In September, 1905, having refused to sur- 

 render his certificate as second mate, a Local Marine 

 Board was called to inquire into his competency. The 

 board found that he was not incompetent to hold his 

 certificate by reason of colour-blindness. In May, 

 1906, he was examined for a certificate of com- 

 petency as first mate; he passed the examination, 

 including the sight-test. The Board of Trade was 

 not satisfied, and, after some correspondence, he was 

 oft'ered and accepted a special examination bv Sir 

 William Abney and Captain Harvey. It took place in 

 .May, 1909, when he again failed in the colour-vision 

 test. He declined voluntarily to surrender his second 

 mate's certificate, and the Board of Trade instituted 

 a special court, consisting of Sir Francis Mowatt, 

 president, with Mr. J. Dickinson, stipendiary magis- 

 trate, as legal assessor, to decide the issues. Mr. 

 Trattles therefore came before this court after six 

 examinations in colour-vision during the last six 

 \'ears ; on three occasions he passed, and on three occa- 

 sions he failed. 



On the occasion of the special examination bv Sir 

 William Abney and Captain Harvey in Mav, 1909, 

 owing, presumably, to the agitation in the medical and 

 lay Press against the methods adopted by the Board 

 of Trade, certain scientific bodies were invited to send 

 representatives to witness the tests. Dr. W. H. R. 

 Rivers, F.R.S., lecturer in the physiology of the senses 

 in the University of Cambridge, and Mr. J. Herbert 

 Parsons were present, representing the Royal Society 

 and the Ophthalmological Society respectively. These 

 gentlemen were not informed that the case was one 

 likely to render desirable their evidence as witnesses 

 in a court of law. Dr. W. Ettles, who had examined 

 Mr. Trattles, ' and was of opinion that he was not 

 colour-blind, was also present. 



The special court commenced its sittings on Decem- 

 ber 2, 1909, at the Imperial College of Science and 

 Technology, South Kensington. Evidence was given 

 by Sir William Abney, Dr. Rivers, Mr. Herbert Par- 

 sons, Captain Harvey, Captain Fulton, and Fleet- 

 Surgeon Prynn, R.N.; they concurred in their opinion 

 that Mr. Trattles was colour-blind. Mr. Trattles's 

 witnesses included himself and several well-qualified 

 captains, who had had extensive experience of his 

 skill and ability in navigating ships under conditions 

 of difficulty in the North Sea, the Baltic, the Channel, 

 the Atlantic, the Mediterranean, the Black Sea, and 

 in the Mersey. We do not notice the name of Dr. 

 Ettles in the reports we have seen ; we should have 

 thought that he would have been an important witness 

 for the defence. Mr. Trattles submitted to an examina- 

 tion before the court, conducted by Sir William Abney. 

 The court further allowed a practical test, conducted 

 by Commander Wilson-Barker, R.N.R., who was 

 nominated by the Trinity House Brethren. It took 

 place on the evening of December 30, when it was 

 "calm, with some haze on the horizon." Commander 

 Wilson-Barker reported that " Trattles had no difificulty 

 whatever in picking up the lights. He had vision of i 

 NO. 2100, VOL. 82] 



a quality equal to that of myself .'ind of the look-out 

 man." He instanced two tests to which he attached 

 special importance. On approaching the Nore light 

 at some distance off, Trattles hesitated, questioning if 

 it was not a reddish light. He was correct, the light 

 being a new white light in which some ruby rays are 

 retained as an experiment in penetrating the fog. 

 Trattles was asked to describe the colour of two 

 planets which the Commander pointed out to him 

 from the deck ; he did not recognise them, but he 

 correctly described one of them (.Mars) as reddish. 

 Sir Francis Mowatt came to the conclusion that Trat- 

 tles is not incompetent from colour-blindness to dis- 

 charge the duties of a mate, and directed that his 

 certificate as second mate be returned to him. 



We have quoted this case at considerable length 

 because, in our opinion, it demonstrates beyond dis- 

 pute the urgent need of reform in the methods of 

 conducting inquiries into the colour-vision of candi- 

 dates by the Board of Trade. Here is a man, with 

 an unimpeachable record in his profession, whose lite 

 must have been made a misery from anxiety as to his 

 future career. On the other hand, the public cannot 

 but feel perturbed at the thought that numberless lives 

 are endangered if mistakes are allowe'd to occur. 

 There are obviously two explanations of the anomaly 

 that the same man may be rejected by the same tests 

 conducted by difierent examiners; either the tests 

 themselves are at fault or, if eflicient, they are not 

 applied with suflicient care or accuracy. Experts 

 whose opinions cannot be lightly disregarded will be 

 found to support both these contentions. For our own 

 part, for reasons which it would take too long to enter 

 into on the present occasion, we incline to the second 

 alternative. The preliminary examinations are con- 

 ducted by men who have no knowledge of physiology, 

 whatever their other qualifications may be. Even on 

 appeal there is no physiologist amongst the examiners. 



We do not wish to labour this point unduly, but 

 owing to the manner in which it has been neglected 

 in the past it merits serious consideration. Defects 

 of colour-vision are defects of a physiological condi- 

 tion, and belong to the class of conditions which the 

 ])hysiologist is accustomed to deal with. Every 

 physiologist to-day must perforce be a more or less 

 accomplished physicist ; every physicist is by no means 

 called upon to be an equally accomplished physiologist. 

 The physiologist is familiar with those tantalising 

 variations which characterise living matter, induced 

 by the lability of the medium and the complexity of 

 the forces brought to bear upon it. Even amongst 

 physiologists and ophthalmologists, only those who 

 have devoted particular attention to this highly 

 specialised branch are fully qualified to deal with it. 

 Normal colour-vision shows a great range of variations 

 under differences of intensity of stimulation, differ- 

 ences of adaptation of the retina, differences of the 

 psychological condition, and in different individuals. 

 To take a simple example, the fields of vision for 

 colours vary according to the intensity of the stimulus. 

 Defects of colour-vision show an equally wide range, 

 and whilst it is possible to group the cases according 

 to certain well-defined types, there is none of that 

 accuracy of definition in the scientific picture which 

 rejoices the heart of the physicist. Whilst compara- 

 tively gross tests, such as the ordinary tests with 

 Holmgren's wools, used in preliminary examinations 

 by the Board of Trade, suffice to distinguish the 

 graver forms of defective colour sensation, they 

 cannot, as ordinarily applied, be regarded as infallible 

 in less pronounced cases — cases which may yet involve 

 danger to many lives if they are allowed to pass un- 

 recognised. Hence occurs the necessity for more 

 delicate tests, physical indeed in their nature, but 



