The detection of colour-blindness & imperfect eyesight by the methods of Dr. Snellen, Dr. Daae, and Prof. Holmgren : with a table of coloured Berlin wools and sheet of test-types / by Charles Roberts.

  • Roberts, Charles, 1836-1901.
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: The detection of colour-blindness & imperfect eyesight by the methods of Dr. Snellen, Dr. Daae, and Prof. Holmgren : with a table of coloured Berlin wools and sheet of test-types / by Charles Roberts. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    It is always desirable to repeat the examination again and again if it has not proved satisfactory in the first instance. If it be desu'ed to test or to qualify the result of an examination one colour should be pointed out, and the candidate required to find all the similar colours on the table. Suppose red, say 5 g, is pointed out, and the candidate is found able (although with some difBiculty) to point out the other red pattern, he evidently shows a keener perception for red than if he were to associate it with grey, brown, or (as sometimes happens) with green colours. The same method may be employed with other colours, but it should be remembered that, generally, light colours are more apt to engender mistakes than saturated tints. Test II.—According to Holmgren, those who would associate with purple (magenta), 6 c, a blue and a violet, or either tint, are redzhlmd; and those who would associate with a similar pattern, 4 c, green and grey tints, or either of these, are green-hlind. . Persons associating yellow and other colours with 1, 2 and 4 D; yellow or grey with blue, 1 e ; or blue and grey with yellow (lines 1 and 2);—suffer from hlue-yelloiv-hlmdness. a. In lines 1 and 2 of the table the characteristic combina- tions of hlue-yelloiv-blindness are demonstrated. h. In lines 3 and 4, that kind of red-green-blindness which is known as green-blindness, c. In lines 5, 6 and 9, that kind of red-green-blindness known as red-blindness.