Civilisation and Eyesight

Abstract

IN reading Lord Rayleigh's interesting remarks in NATURE (p. 340) upon Mr. Carter's paper, it has occurred to me that we should not, in considering the question of “aperture,” entirely omit the fact that this, though probably following a general rule applicable alike to savages and civilised beings, varies in individual cases. An assistant, who has recently left my observatory, had a singularly “sharp” eye, and could pick up with ease companions to double stars, small satellites, &c., which others saw with difficulty. Such were his powers in this respect that I always appealed to him in the case of a doubtful observation. I noticed one day how large the pupils of his eyes were, so large that I asked him if he had taken anything to artificially dilate them. Subsequent examination proved that they were, though of course varying with the stimulus of light, always much larger than those of most other persons, so much so that I laughingly used to call them “cat's eyes.” They had also, in fact, a peculiarity, attributed to feline sight, that he could read fine print and distinguish lines by a light much less bright than I could, and habitually used the gas half turned on, &c. Probably such instances would not be rare if they were looked for. Another question arises on this head: Could it be possible that such a condition of the eye, natural in some persons, could, by certain uses of the member, be fostered in others?