A case of colour blindness / by F.W. Edridge-Green.

  • Edridge-Green, F. W. (Frederick William), 1863-1953.
Date:
1912
Catalogue details

Licence: In copyright

Credit: A case of colour blindness / by F.W. Edridge-Green. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Reprinted from The A CASIA^F ^C0|4qfRs Bt^DNBSS. By F. W. EDRlnj^-<^REEN. Diiin^, F.R C.S Eng., BEIT^E^MAL '^SEARCH ^iSoW. {JBrom the Institutesity College, London.) by me for the first time. 1. Examination with my lantern.—This examination was made with the largest aperture of my lantern, measuring seven-eighths of an inch in diameter. He called red A, nothing and green; yellow, red ; red B, white ; neutral 1, green ; and green, white and red. This test was the shortest of any I made and lasted less than a minute, as I only asked the subject of it at the most to name 15 lights. 2. Examination with the official test of the Board of Trade. — This test is an improved Holmgren wool test in which two new test colours have been added similar to the violet and orange in my classification test. The examinee picked out and matched all five test colours, green, rose, red, purple, and orange-yellow, easily and correctly ; he did not touch a confusion colour. Had I examined him by this test alone I should have passed him and had no suspicion that he was colour blind. It must be noted that colour names must not be used in testing by the Holmgren method. 3. Examination with my spectrometer.—The examinee said that the spectrum consisted of two colours, red and purple, with an intermediate yellowish or no colour between. The red commenced at X670. The uncolonred region, which was quite uniform, extended from \586-X516. The purple extended from X516-X400. The most luminous portion of the spectrum was X527-X583. 4. Lord Rayleigh's colour-mixing apparatus —This instru- ment is for making a mixture of thallium green X535 and lithium red X670 to match sodium yellow X589. An abso- lutely normal match under rather difficult conditions was made by the man. His match was the same as that of Pro- fessor Trouton, Professor Porter, and myself. I must state- in justice to Lord Rayleigh that this instrument, which he has kindly lent me, was not constructed as a test for colour blindness, but for ascertaining the variations which are found in different people in making the above match. It is, in my opinion, the best piece of apparatus which has yet been designed for this purpose. I give the above observation simply as an example of his ability to make this match, as it is generally stated that a colour-blind person is not able to do so. 5. Nagel's test —Passed. 6. Stilling's test.—Could not read some of the figures. Rejected. 7. My head test.—Rejected. Left many definite colours ; put yellow with green and called yellow, green and put violet with blue. 8. My pochet test.—Rejected. Called brown, red ; green, grey ; and green, red-green. 9. My classification test.—1. (Orange.) Orange and yellow-brown, 2. (Violet ) Violet, blue, and rose wools; blue glass and blue silk; purple wool, silk, and cards. 3. (Red.) Red wool ; rose silk ; purple glass and orange card. 4. (Blue-green). Green and brown wools; brown, yellow, and grey silks and neutral glass. ^ The following case i *a man, aged 20 years, seen