Letter | Published:

Colour Vision and Syntony

Nature volume 110, page 668 (18 November 1922) | Download Citation



AFTER reading the letter of Dr. Edridge Green (NATURE, October 14, p. 513) it occurred to me that the following method, involving no head movement, of observing the movement of positive retinal “after images” might be of interest. If, in a dark room, the eyes being in a state of “dark adaptation” and one covered, a dry petrol lighter of the spring release type be flashed, a fan-shaped pattern of brilliant streamers will be seen. This pattern is followed by a similar “after image.” The “after image” immediately begins to contract. This contraction continues till the after image appears as a rather thick irregular line of smaller area and greater brilliancy than the original pattern. The rapidity of the change, and the final form varies for different parts of the retina. Two points are of interest, the contraction of the image, and the increase of brilliancy.

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  1. London, S.E., Oct.16.

    • H. S. RYLAND


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