Sir George Biddell Airy, F.R.S. (1801-1892) and the discovery and correction of astigmatism

Abstract

THE independent discovery and correction of astigmatism by George Biddell Airy (1), was described in a paper read before the Cambridge Philosophical Society, on 21 February 1825, and subsequently printed in the Transactions of that Society (2). The term ‘astigmatism’ was at a later time suggested to Airy (3), to describe the anomaly, by Dr William Whewell (1794-1866; F.R.S., 1820), Master of Trinity College, Cambridge. While still a student at Trinity College, Cambridge, Airy had noticed that when reading, or looking at any near object with his left eye ‘ . . . it was totally useless: in fact, the image formed in that eye was not perceived except my attention was particularly directed to if (4). Supposing the ‘disuse’ of the eye to be due to habit, Airy tried closing or occluding the right eye, in an attempt to use the left eye as much as possible, but without success. He did find, however, that by tilting his spectacle lens obliquely, or by looking at a point near the edge, he could see objects clearly. When Thomas Young (1773-1829; F.R.S., 1794), a quarter of a century before, had mentioned his own ocular defect (astigmatism) to the scientific instrument maker, William Cary (1759-1825) the latter remarked that ‘ . . . many people were obliged to hold a concave glass obliquely, in order to see with distinctness’ (5). Whereas Young’s refractive error was comparatively low, and the distortion, if any, produced by tilting his spectacle lens was not perceptible, with Airy, whose refractive error was considerably higher than Young’s, the distortion produced by a tilted lens was too uncomfortable to tolerate. Airy therefore turned his mind to serious experimentation and to the theory and practical applications of a cylindrical lens, in an attempt to correct the anomaly.