Note of a method of studying the binocular vision of colour / by John G. M'Kendrick, M.D.

  • McKendrick, John G. (John Gray), 1841-1926.
Date:
[1877?]
Catalogue details

Licence: Public Domain Mark

Credit: Note of a method of studying the binocular vision of colour / by John G. M'Kendrick, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    of Edinburgh, Session 1877-78. spectrum—the method of reflection, Czermak’s modification of Scheiner’s experiment, the use of rotating disks having coloured sectors, and the direct mixture of coloured powders or coloured liquids. In all of these cases the effect may he seen with one eye, and is due to the action of light on a definite portion of one retina. But may sensations of mixed colours he produced by binocular vision of the components 1 Regarding this question various well- known observers have arrived at completely opposite results. Thus, as mentioned by Helmholtz in his “ Optique Physiologique,” p. 976, H. Meyer, Yolkmann, Meissner, Eunke, and he himself fail in ob- taining the sensation of the resulting colour, whilst Dove, Regnault, Briicke, Ludwig, Panum, and Hering state the reverse. In his great work, Helmholtz describes various methods by which he investigated the question, and his opinion amounts to this, that we have no true binocular perception of colour. According to him we may have a resultant sensation of a particular kind, different from that of the two components, but also unlike the sensation of the mixed colour obtained by methods appealing to one eye only. In studying this subject I lately devised the following simple arrangement:—Take two Ho. 3 eye-pieces of Hartnack’s microscope, or any similar eye-pieces of considerable focal length, and place one before each eye. If they be somewhat diverged, two luminous fields will be seen, and by adjustment, the edge of the one luminous field may be caused to touch the edge of the other. In these circum- stances a definite area of each retina is illuminated. By converg- ing the eye-pieces, the two fields may then be partially overlapped, and when the axes of the two eye-pieces are parallel, both fields coincide. It will then be found that the overlapped portion is in- tensely luminous, whilst the other portions become less luminous, as if cast into shadow. By increasing or diminishing the amount of convergence of the eye-pieces, the extent of the luminous field may be varied at pleasure, and the two fields coincide when the two images fall on the two yellow spots. If, then, a small piece of coloured glass be inserted into each eye-piece, say red into one and blue into the other, on repeating the experiment as above mentioned, I find that the overlapping portion of the two fields gives a sensa- tion of the resultant colour. I have repeated the experiment with various coloured media, such as coloured gelatine paper, coloured