SKETCH OF PROFESSOR SIMON NEW COMB. 613 



associated with any brilliant discovery or achievement in astrononi}-, 

 he has, nevertheless, secured as great a reputation as was ever gained 

 by an American astronomer, and is quoted abroad as among the high- 

 est authorities in mathematical astronomy. Perhaps the secret lies 

 in the unity of purpose which has characterized all his efforts. His 

 special field has been that of " exact " astronomy the prediction of 

 the motions of the heavenly bodies from their mutual gravitation 

 the perfection of the tables and other data, from which the " Nautical 

 Almanac " is prepared, in order that the navigator and surveyor may 

 be enabled to find their positions by sea or land. When the late 

 Admiral Davis founded the "American Nautical Almanac," some 

 twenty-five years ago, the tables and other materials for its construc- 

 tion were extremely imperfect, but Prof. Newcomb's studies have all 

 tended to their improvement. 



Prof. Newcomb gained a European reputation while still a com- 

 puter at Cambridge, by his paper " On the Secular Variations and 

 Mutual Relations of the Orbits of the Asteroids." The question of 

 the correctness of Olher's theory, that these bodies resulted from the 

 explosion of a single planet, had never been decided, because no one 

 had ever investigated the changes which their orbits had undergone 

 in past ages. This was done in the paper we have mentioned, and it 

 was shown that the orbits could never have intersected in a single 

 point, unless they had in the mean while been deranged by some un- 

 known cause. 



Since his appointment in the navy his most considerable works, 

 outside of his duties at the observatory, have been the "Investiga- 

 tion of the Orbits of the Two Outer Planets, Uranus and Nieptune," 

 accompanied by elaborate tables, which were at once adopted in all 

 the nautical almanacs of Europe and America. In the preparation of 

 these " tables," Prof. J. Henry, his kind and firm friend of now more 

 than twenty years, took great interest, and gladly assisted him by 

 supplying him with funds from the Smithsonian. 



In 1867 the observatory published his "Investigations of the Dis- 

 tance of the Sun," leading to the value of the Solar Parallax now 

 most generally adopted, namely, 8", 84 8. 



In 1870 he visited Europe to observe the total eclipse in the Medi- 

 terranean, and was everywhere received with the highest distinction 

 in scientific circles. 



He took an active part in procuring the great telescope for the 

 Washington Observatory, and was in charge of it during the first 

 year or two after its erection, investigating with it the satellites of 

 his two favorite planets, Uranus and Neptune. 



When Congress authorized the organization of parties to observe 

 the late transit of Venus, Prof. Newcomb was appointed one of the 

 commission to prepare the plans for those parties, and to arrange for 

 the complete execution of those plans, after the return of those parties 



