124 PROCEEDINGS OF THE AMERICAN ACADEMY 



years' professorship, who have had a large share in aiding the progress 

 of astronomical knowledge. But astronomy in America is most indebted 

 to him for his papers on the Method of Least Squares, and on the Com- 

 putations of Special Perturbations. The Method of Least Squares, 

 which originated with Legendre and Gauss, was systematically and 

 successfully applied in Encke's earlier investigations upon the motions 

 of the comet which bears his name, and its inestimable practical value 

 illustrated. His papers on the subject, together with the numerous 

 examples which his applications of it furnish, have placed the method 

 easily within reach of the student, and have enabled many a young 

 mathematician, with no other aid, to proceed with confidence and success 

 in computations which could never have been undertaken otherwise 

 without the instructions of a master. So admirable have been his 

 arrangements of these difficult computations, and so explicit his instruc- 

 tions upon every part of the work, that it may be truly said that the 

 greater part of what has been done since by astronomers anywhere in 

 the correction of orbits of comets or minor planets, or the computation 

 of their perturbations, has been done under Encke's direction. It was 

 in such work as this that he excelled ; and while he showed no want of 

 ability to take the highest rank in any department of theoretical or 

 practical astronomy, it was as a computist that he was pre-eminent. 



Sir John William Lubbock, Baronet, was born March 26, 1803 ; 

 educated first at Westminster School, then at Trinity College, Cam- 

 bridge, taking the Bachelor's degree in 1825, the Master's in 1833 ; was 

 admitted to the Royal Society (of which he was a Vice-President at 

 the time of his death) in 1829 ; married in 1833 ; succeeded to the 

 baronetcy in 1840, on the death of his father, the eminent banker, Sir 

 John Lubbock ; and transmitted the title to his eldest son, John, — also 

 of scientific eminence, — by his death at High Elms, Kent, June 20, 

 1865. Between the time of reading his memoir on the determination 

 of the orbits of comets before the Royal Society in 1829 and the year 

 1849, he contributed more than forty papers to the Transactions of that 

 body and of other learned societies, on the moon and the tides, the per- 

 turbations of planets, the orbits of comets, and other matters of astron- 

 omy, terrestrial physics, and pure mathematics. 



He holds a conspicuous place among those who have contributed to 

 the perfection of the Lunar Theory. His claims are thus stated by 

 himself in the Transactions of the Royal Astronomical Society for 1860 : 

 " I am confident that a just posterity will give to us [that is, to Plana, 



