908 SIMON NEWCOMB. 



SIMON NEWCOMB (1835-1909) 



Fellow in Class I, Section 1, 1860. 



Simon Newcomb may justly be compared with the great leaders of 

 commerce and finance who have risen up during the past half-century, 

 and who have had so large an influence on the development of Ameri- 

 can industry. That he was early drawn to astronomical science may 

 be regarded as an accident of his career. As soon as he found himself 

 in a position where his ideas could have free scope he set to work to 

 condense and organize the cloud of facts and observations which was 

 rapidly producing chaos in the astronomy of position. Different 

 investigators were using different values for the fundamental constants 

 of astronomy and the catalogues were affected by personal equations 

 and instrumental errors; Newcomb sought to eliminate these and to 

 combine observations from every source to produce values which 

 would be generally accepted, or which could be made the basis for all 

 future investigations. In this aim he was successful. Practically 

 all investigations of the present day which lead to the determination 

 of the constants of the star system, and to those of precession, nuta- 

 tion, aberration, etc., are compared with Newcomb's results and hence 

 are comparable with one another. 



This achieved, he set to work on a much longer task, that of pro- 

 ducing new values and tables of the motions of the eight major 

 planets of the solar system. He soon recognized that this was too 

 large an undertaking for one man, even with a considerable force of 

 computers at his disposal. For the most difficult portion, namely the 

 theories of Jupiter and Saturn, he was fortunate in securing the 

 services of the one man who had the requisite knowledge and ability 

 to perform the task, G. W. Hill. All the rest of the work was carried 

 on under Newcomb's supervision. When the construction of the 

 theories from gravitation had been completed, he carried through a 

 comparison of them with over sixty thousand meridian observations 

 in order to determine with the highest possible accuracy the constants 

 of their orbits. The tables embodying these results were then formed 

 and are used in most of the national ephemerides. 



The chief attraction to him, however, was the motion of the Moon. 

 By comparisons with early occultations and eclipses for the records 

 of which he ransacked many European libraries, he discovered the 

 great fluctuation from its theoretical orbit which the Moon possesses 

 and which is yet awaiting an explanation. From the modern occulta- 



