Color blindness : remarks / by B. Joy Jeffries at the twenty-ninth annual meeting of the board of the supervising inspectors of steam vessels.

Jeffries, B. Joy, 1853-

Date:: [1881]

Credit: Color blindness : remarks / by B. Joy Jeffries at the twenty-ninth annual meeting of the board of the supervising inspectors of steam vessels. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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$\ 21 Before discussing the general question of the uselessness of testing the color sense by lanterns, I would call the hoard's attention to some very practical points. The local inspectors are provided with signal-lights; the precise kind and standard are not stated or defined. ]^ow, in reality, the glass varies very much. It will be remembered that the red or green-blind see yellow and blue as we do. 'Now, here, directly from the manufactory, is a very strong bltcish-green starboard-light that any color-blind would see and recognize the color in it, namely, the blue. He would, of course, call it the starboard-light or green. The name is nothing j he calls it what we do, green; and here is another starboard-light which is a pale yellowish-gieew, the yellow in this tells him that it is also what he is to call green when asked to name it, and he does so unhesitatingly. Any light differing from these two he equally unhesitatingly calls red, in which he, of course, will be right. !N^ow, practically, this is what frequently occurs as told me by the manu- facturers. A shipmaster buys the dark greenish-blue, and as it gives so very little light it is complained of, and he comes back with his com- plaint to the seller, who then substitutes the pale yellowish-green. This is, however, soon returned, and complaint made that it does not look different from an ordinary white light, and the exchange is again made for the dark bluish-green, &c. Now the railroad lights vary in precisely the same way, and officials have been puzzled by finding employes who were by experts detected as color-blind, naming, when close enough, (this is the point,) the colored signals (bluish-green and pale yellowish-green) apparently quite correctly, of course calling all else shown red, as it would, of course, be. [A member of the board here asserted that any vessel using such a light as the bluish-green one shown by Dr. Jeffries would be liable under the law. But 'the Inspector-General replied that this was not the case, and that the two so different starboard-lights exhibited would equally well meet all the present legal requirements.] Thus it will be seen that a local inspector provided with certain signal- glasses would never find a color-blind pilot, and quite readily convince himself and the pilot and the persuasive f riends that the Department or- der!, Holmgren's test, and even the existence of color-blindness, were all scientific refinements of no practical meaning or value; and, as a Chicago paper, seriously says, that the suggester of this whole move- ment, &c., ought to be put in prison and the Government indicted by the oppressed color-blind pilot. Any test by naming colors has been shown to be simply ridiculous, yet any examination by signal-lights must of course be by requiring the examined to say what he sees. Every time he fails it must be put down against him, and, if he has to correct himself, it must be a cause of suspicion. Moreover, whenever the true color-blind guesses rightly, which he may do every time, as it is only between two colors, it is to his credit in proving him not color-blind. The whole thing will be a mere play of wits between examined and examiner, as unfair for one as the other. I myself now feel pretty familiar with this peculiar chro- matic defect and its manifestation, yet I do not hesitate to say that if I was forced to use only signal-lanterns in detecting it I would refuse to attempt to give an opinion. All scientific experts who have had practical experience entirely agree with me in this. There is no differ- ence of opinion. The Supervising Surgeon-General well says, in his Annual Eeport, p. 21: When signal-lights are proposed as tests for •$