The Times a short time ago, in a very interesting
paper 'on colour-blindness, brought out the very great danger.to which, in certain callings, colour-blindness, especially when not recog- nised by those who suffer from it, exposes both themselves and the public. Among nearly 8,000 railroad employ6s in Sweden, to whom the power to discriminate at once the colour of the various signal-lamps and signal-flags is quite essential, 215 per cent. were found on testing to be colour-blind; while of nearly 1,500 tested in Swiss schools and avocations, 6.58 per cent. were colour-blind. Among 10,387 males in American schools and colleges, 288 were found to be unable to discriminate reds, 75 greens, and 68 were partially colour-blind, making a total of 431, or 4149 per cent. These last observations were made by; Dr. Jeffries, the author of the book on colour-blindness published by UsgoodEof Boston, and reviewed in the Tintes, and Dr. Jeffries gives abundant evidence to show that it is a defect very often transmitted by descent from generation to generation. It ap- pears, however, that not infrequently it is rather want of atten- tion and teaching, than absolute want of faculty, which produces an apparent inability to distinguish colours. Mr. W. H. Stone mentions, in a letter to the Timea of Monday, an interesting case in one of the wards of St. Thomas's Hospital, in which a costes- monger, who at first appeared to be colour-blind, was taught by one of the Sisters his "chromatic alphabet" (which is learnt on properly assorted skeins of Berlin wool), and .u,t.last became a proficient in it.
Previous page
