1909.] Anniversary Address by Sir A. Geikie. 



165 



MEDALLISTS, 1909. 

 Copley Medal. 



The Copley Medal is this year awarded to Dr. George William Hill, 

 For.Memh.E.S. Now that Simon Newcomb is no longer with us, Dr. Hill 

 occupies, beyond challenge, the first position in tlie great subject of Dynamical 

 Astronomy. 



His processes are not only marked by extraordinary originality, the result 

 of high mathematical genius, but also in every case his methods and researches 

 are directed towards practical astronomical ends. His supreme work is 

 probably contained in his researches on the theory of the moon's motion, 

 which has remained the great problem of gravitational astronomy ever since 

 the time of Newton. Here his introduction and development of the principle 

 of disturbed periodic orbits has given an entirely new direction to the science, 

 culminating recently in the Lunar Tables of E. W. Brown, which mark an 

 epoch in the practical side of the Lunar Theory. 



This work of Hill bas been fruitfiil in new advances in many directions. 

 His ideas have given rise, as developed by Poincare and other investigators, 

 to new departments of abstract mathematical analysis, while in the hands of 

 Lord Eayleigh they have shed light on important and difficult problems of 

 general mathematical physics. 



His collected works have recently been published by the Carnegie 

 Institution of Washington in four quarto volumes ; the importance of their 

 contents can hardly be over estimated. M. Henri Poincare, in his introduc- 

 tion to these volumes, described Hill as " une des physionomies les plus 

 (iriginales du monde scientifique americain." 



Astronomy owes to him new theories of the motions of the systems of 

 Jupiter and Saturn, to which the whole of Vol. Ill of his works is 

 consecrated. 



His shorter papers deal with nearly every problem in the Lunar and 

 Planetary theories, with mathematical geodesy and other subjects. All his 

 work is characterised by its original points of view combined with practical 

 aims, by maturity of thought and high suggestiveness. It forms an index of 

 the simplicity and aloofness of its author, who has been one of the main 

 ornaments of Astronomical Science for more than a generation. 



EoYAL Medals. 



One of the Koyal Medals has been awarded, with the approval of His 

 Majesty the King, to Prof. Augustus Edward Hough Love, F.Pi.S., in 



