448 GEORGE BIDDELL AIRY. 



practically terminated by the acceptance of his new office. New in- 

 struments were to be planned, and their construction superintended ; 

 new brauches of scientific work were to be introduced as part of the 

 regular business of the Observatory ; old observations were to be col- 

 lected, reduced, and published ; the methods of making and reducing 

 new observations were to be brought into systematic form; while, in 

 addition to these occupations, demands from other departments of the 

 national administration for advice and assistance in scientific matters 

 were frequently to receive attention from the Astronomer Royal. 

 Substantial progress in any science can only be made by the patient 

 accumulation of observed facts under the guidance of capable adminis- 

 trators, such as Airy. His success in this field of work had to be ac- 

 cepted by himself and by his friends as amends for the withdrawal of 

 his attention from the more strictly scientific problems which he had 

 shown himself so well qualified to solve. 



During his administration of the Greenwich Observatory its instru- 

 mental equipment was entirely renewed, and in many respects greatly 

 enlarged ; magnetic and meteorological observation, and long after- 

 wards spectroscopic observation, were undertaken as parts of the pre- 

 scribed system of work ; the results of older and recent observations 

 were made accessible to the scientific public in a long series of ponder- 

 ous volumes, to which the astronomical investigators of this century 

 have constantly resorted for an important portion of the facts needed 

 in their studies. No enumeration of the details of Airy's work as As- 

 tronomer Royal will be attempted in this place ; and as an individual 

 student of nature little remains to be said of him, for the reasons above 

 stated. But his interesting experiments at the Harton Colliery, in 

 1854, for the determination of the density of the Earth by the obser- 

 vation of pendulums at the surface of the ground and at the bottom of 

 the mine, deserve mention in any notice of his life. In 1870 he began 

 an elaborate investigation into the theory of the Moon's motion, by a 

 new method; but, after pursuing it for many years in such time as was 

 at his command, he found that old age forbade him to carry it further. 

 He resigned his position as Astronomer Royal in 1881, and lived in 

 honored retirement for the ensuing ten years, dying on January 7, 

 1892, in consequence of an accidental fall some time before. Marrying 

 in 1830, he became a widower in 1875. Six children survive him. 

 He received the honor of knighthood in 1872, and a long series of 

 other complimentary distinctions at various times in his life. 



Besides his original researches, he published, chiefly in his younger 

 days, various essays on scientific matters, distinguished by their accu- 

 racy and perspicuity. 



