No. 1072, Vol. 42] 



NATURE 



59 



Whether a similar difference exists between females of 

 different classes, we have no statistics to establish. The 

 condition of colour-blindness is absolutely incurable, ab- 

 solutely incapable of modification by training or exercise, 

 in the case of the individual ; although the comparative 

 immunity of the female sex justifies the suggestion that 

 it may possibly be due to training throughout successive 

 generations, on account of the more habitual occupation 

 of the female eyes about colour in relation to costume. 

 However this may be, in the individual, as I have said, 

 the defect is unalterable ; and if the difference between 

 red and green is uncertain at eight years of age, it will 

 be equally uncertain at eighty. Hence the existence of 

 colour-blindness, among those who have to control the 

 movements of ships or of railway trains, constitutes a 

 real danger to the public ; and it is highly important that 

 the colour-blind, in their own interests as well as in those 

 of others, should be excluded from employments the 

 duties of which they are unfit to discharge. 



The attempts hitherto made in this country to exclude 

 the colour-blind from railway and marine employment 

 have not been by any means successful. As far as the 

 merchant navy is concerned, so-called examinations have 

 been conducted by the Board of Trade, with results 

 which can only be described as ludicrous. Candidates 

 have been '■ plucked " in colour at one examination, and 

 permitted to pass at a subsequent one ; as if correct 

 colour-vision were something which could be acquired. 

 Such candidates were either improperly rejected on the 

 first occasion, or improperly accepted on the second. On 

 English railways there has been no uniformity in the 

 methods of testing ; except, in so far as I am acquainted 

 with them, that they have been almost uniformly mislead- 

 ing, calculated to lead to the imputation of colour-blind- 

 ness where it did not exist, and to leave it undiscovered 

 where it did. In these circumstances it is not surprising 

 that great discontent should have arisen among railway 

 men in relation to the subject ; and this discontent has 

 led, indirectly, to the appointment of a Committee by the 

 Royal Society, with the sanction of the Board of Trade, 

 for the purpose of investigating the whole question as 

 completely as may be possible. 



It is perhaps worth while, before proceeding to describe 

 the manner in which the colour-sense of large bodies of 

 men should be tested for industrial purposes, to say some- 

 thing as to the amount of danger which colour-blindness 

 produces. A locomotive, as we all know, is under 

 the charge of two men— the driver and the fireman. 

 In a staff of one thousand of each, allotted to one 

 thousand locomotives, we should expect, in the absence 

 of any efficient method of examination, to find forty 

 colour-blind drivers, and forty colour-blind firemen. 

 The chances would be one in twenty-five that either the 

 driver or the fireman on any particular engine would be 

 colour-blind ; they would be one in 625 that both would 

 be colour-blind. These figures appear to show a greater 

 risk of accident than we find realized in actual working, 

 and it is manifest that there are compensations to be 

 taken into account. In the first place, the term "colour- 

 blind " is itself in some degree misleading ; for it must be 

 remembered that the signals to which the colour-blind 

 person is said to be "blind" are not invisible to him. To 

 the red-blind, the red light is a less luminous green ; to 

 the green-blind, the green light is a less luminous red. 

 The danger arises because the apparent differences are 

 not sufficiently characteristic to lead to certain and 

 prompt identification in all states of illumination and of 

 atmosphere. It must be admitted, therefore, that a 

 colour-blind driver may be at work for a long time with- 

 out mistakes ; and it is probable, knowing as he must 

 that the differences between different signal lights appear 

 to him to be only trivial, that he will exercise extreme 

 caution. Then it must be remembered that lights never 

 appear to an engine-driver in unexpected places. Before 



being intrusted with a train, he is taken over the line, 

 and is shown the precise position of every light. If a 

 light did not appear where it was due, he would naturally 

 ask his fireman to aid in the look-out. It must be also 

 remembered that to overrun a danger signal does not of 

 necessity imply a collision. A driver may overrun the 

 signal, and after doing so may see a train or other ob- 

 struction on the line, and may stop in time to avoid an 

 accident. In such a case, he would probably be reported 

 and fined for overrunning the signal ; and, if the same 

 •thing occurred again, he would be dismissed for his 

 assumed carelessness, probably with no suspicion of his 

 defect. Colour-blind firemen are unquestionably thus 

 driven out of the service by the complaints of their 

 drivers ; and none but railway officials know how many 

 cases of overrunning signals, followed by disputes as to 

 what the signals actually were, occur in the course of a 

 year's work. I have never heard of an instance in this 

 country, in which, after a railway accident, the colour- 

 vision of the driver concerned, or of his fireman, has been 

 tested by an expert, on the part either of the Board of 

 Trade or of the Company ; but a fireman in the United 

 States has recently recovered heavy damages from the 

 Company for the loss of one of his legs in a collision 

 which was proved to have been occasioned by the colour- 

 blindness of the driver. Looking at the whole question, 

 I feel that the danger on railways is a real one, but that 

 it is minimized by the several considerations to which I 

 have referred, and that it is much smaller than the fre- 

 quency of the defect might lead us to think likely. 



At sea, the danger is much more formidable. The 

 lights appear at all sorts of times and places, and there 

 may be only one responsible person on the look-out. Mr. 

 Bickerton, of Liverpool, has lately published accounts 

 of three cases in which the colour-blindness of officers 

 of the mercantile marine, all of whom had passed the 

 Board of Trade examination, was accidentally discovered 

 by the captains being on deck when the officers in ques- 

 tion gave wrong orders consequent upon mistaking -the 

 light shown by an approaching vessel. The loss of the 

 Ville du Havre was almost certainly due to colour- 

 bhndness ; and a very fatal collision in American waters, 

 some years ago, between the Isaac Bell and the Liimber- 

 via7t, was traced, long after the event, to the colour- 

 blindness of a pilot, who had been unjustly accused of 

 being drunk at the time of the occurrence. In how 

 many instances colour-blindness has been the unsuspected 

 cause of wrecks and other calamities at sea, it is im- 

 possible to do more than conjecture. 



It is necessary, then, alike in the public interest and in 

 the interest of the colour-blind, who have doubtless often 

 suffered in the misfortunes which their defects have 

 produced, to detect them in time to prevent them from 

 entering into the marine and railway services ; and the 

 next question is, how this detection should be accom- 

 plished. We have to distinguish the colour-blind from 

 the colour-sighted ; but we must be careful not to confound 

 colour-blindness with the much more common condition 

 of colour-ignorance. 



It would surprise many people, more especially many 

 ladies, to discover the extent to which sheer ignorance 

 of colour prevails among boys and men of the labouring 

 classes. Many, who 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 have 

 lately seen a pattern card of coloured silks, issued by a 

 Lyons manufacturer, which contains samples of two 



