Abstract
CAMBRIDGE.
Philosophical Society, November 26.—Prof. J. J. Thomson, President, in the chair.—On Benham's artificial spectrum, by Prof. G. D. Liveing. Prof. Liveing exhibited one of Benham's “artificial spectrum tops”(see NATURE, November 29, p. 113), and a variety of discs with figures in black disposed on a white ground, and with white figures on a black ground, which, when revolved in a bright light showed remarkable bands of colour of various shades of red, green, and blue. The general result of his observations of these discs was that if a succession of black and white objects were presented to the eye with moderate, but not too great, rapidity, then, when black was followed by white, an impression of a more or less red colour was perceived, while when white was succeeded by black a more or less blue colour was perceived. If the succession of black and white was very rapid the appearance presented to the eye was of a more or less neutral green or drab. The explanation offered by Prof. Liveing was based on the known facts that the impression produced on the retina by a bright object remained for an appreciable time after the light from the object had been cut off, and that the duration of that impression was different for different colours; and on a supposition, which he did not know to have been as yet verified experimentally, that the rapidity with which the eye perceives colours was greater for one end of the spectrum than for the other. From this point of view the explanation of the blue colour seen when white is followed by black would be that the impression of blue on the retina lasts a little longer than that of the other colours; while the red colour seen when white succeeds black is due to the greater rapidity with which the eye perceives red light than that with which it perceives blue. If, however, the alternations of white and black succeed each other with sufficient rapidity, the new impression of a white patch will be produced before that of its predecessor has vanished, and there will be an overlapping of impressions, and the sensation will be that of a mixture of colours, or of a more or less neutral tint. So far as he could test the theory by his own eyes it appeared to him that the residual impression, left when the light from a white object was suddenly cut off, was at first green and faded out through a more or less blue or slate colour.—On a simple test case of Maxwell's law of partition of energy, by Mr. G. H. Bryan.
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Societies and Academies. Nature 51, 167–168 (1894). https://doi.org/10.1038/051167b0
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DOI: https://doi.org/10.1038/051167b0