Nevil Maskelyne, F. R. S., and the discovery of Night Myopia

Abstract

It is not surprising that the phenomenon of Night-Myopia, also known as Nocturnal or Twilight Myopia, should have been discovered independently by various astronomers, as the increase in the refractive power of the eye under conditions of reduced illumination would have struck them in their observations. It is the purpose of this paper to describe their contributions and to establish the priority of the discovery to Nevil Maskelyne. Hitherto, priority for the discovery has been generally ascribed to Lord Rayleigh. In 1883 he described his observations in a paper entitled ‘On the invisibility of small objects in a bad light’: `I have found that in a nearly dark room, I am distinctly short-sighted. With concave spectacles of 36” negative focus my vision is rendered much sharper, and is attended with increased binocular effect. On a dark night small stars are much more evident with the aid of the spectacles than without them.’