GEORGE BIDDELL AIRY. 447 



abundantly justified by the number and excellence of the investigations 

 which he began even before his graduation, and continued during the 

 following years. 



The results of his inquiries at this period were published in the 

 Transactions of the Cambridge Philosophical Society, in memoirs relat- 

 ing to optical and astronomical subjects. The reader of these memoirs 

 will not fail to observe, in addition to ingenuity and perspicuity, much 

 evidence that they were written from a genuiue love of inquiry, rather 

 than from the desire for temporary reputation. Although their sub- 

 jects seem at first not very closely connected, it appears that the later 

 inquiries were suggested by facts developed in the course of those which 

 preceded, and that the author was not looking for subjects on which 

 to write, but was impelled to write by the abundance of material which 

 spontaneously presented itself to his mind. As an incidental result of 

 the optical studies in which he was engaged, he discovered and showed 

 how to correct the peculiar defect of vision now so familiar to ocu- 

 lists under the name of astigmatism, which he found to exist in his own 

 left eye. Probably a considerable number of physicians and of phi- 

 losophers must have previously been inconvenienced in the same way 

 without undertaking any experiments to discover the exact nature of 

 the hindrance to distinct vision which existed in their cases. 



Airy began work as a practical astronomer at a time when what we 

 now understand as practical astronomy was an art as yet, comparatively 

 speaking, unformed, — when much now taught in every text-book had to 

 be discovered or neglected by the observer in proportion to his mental 

 activity or indolence. Neglect was impossible to a mind so active anil 

 acute as Airy's ; and while his great contemporary, Bessel,was making 

 the way plain to future practical astronomers, Airy was finding it very 

 successfully for himself. He early recognized and urged the necessity 

 of carefully reducing all observations which are intended to contribute 

 substantially to our knowledge, instead of resting satisfied with the 

 observations themselves. Besides attending thoroughly to all the prac- 

 tical business connected with the management of the Cambridge Ob- 

 servatory, he continued the mathematical investigations which had 

 previously occupied him. Among these should be specially mentioned 

 the memoir on the inequality of long period in the motions of the 

 Earth and Venus, for which the Gold Medal of the Royal Astronomi- 

 cal Society was awarded to him in 1832. 



In 1835 Airy received the appointment of Astronomer Royal, and 

 accordingly took charge of the Greenwich Observatory. Here he re- 

 mained for forty-six years, finding such abundant opport unities for the 

 exercise of his business abilities that his career as an investigator was 



