MEMOIR OF SIMON NEWCOMB 
349 
early epoch of its composition, but the final equations derived are precisely 
those which result from Delaunay’s method. 
Having treated Neptune, Professor Newcomb next undertook a similar 
piece of work for the adjacent planet Uranus. This was a heavier task than 
its predecessor on account of the longer period covered by the observations. 
These theories of the two planets have been superseded by the investigations 
of Professor Newcomb while director of the American Ephemeris, but that 
of Uranus was welcomed by astronomers as a great improvement on the 
discussion of Bouvard. As in the case of Neptune, the investigations of 
Uranus appear in the Smithsonian Contributions to Knowledge. 
In the same collection for the following year, Professor Newcomb has a 
memoir on the general integrals of planetary motion. The aim of this 
paper is to show how to avoid powers of the time as multipliers of the differ¬ 
ent portions of the algebraic expressions arrived at. The thus modified 
expressions have since received the name of Lindstedt’s series and are the 
chief subject of investigation in M. Poincare’s work in the line of celestial 
mechanics. This paper was a worthy beginning for what was to follow. 
Only a few years after the introduction of Hansen’s lunar tables for 
computing the places for the ephemerides, it was seen that observation was 
marching away from them. From the character of the deviation they could 
only be attributed to an imperfect determination by Hansen of the secular 
and long-period terms. Always interested in the theory of the moon, 
Professor Newcomb undertook to see what light could be thrown on the 
matter by observations made before the epoch of 1750, chiefly in the form of 
times of beginning or ending of solar and lunar eclipses and occupations. 
This involved a heavy load of numerical computation and a careful research 
for material in the libraries and observatories of Europe. The results of 
this labor appear in an appendix to the Washington Observations for 1875. 
The memoir led to large modifications in our estimation of the value of 
Hansen’s theory, and it still must serve as a foundation to all future investi¬ 
gations in the subject. 
In 1877, Professor J. H. C. Coffin was retired from the U. S. Navy on 
account of age, and thus the American Ephemeris w r as left without a head. 
Professor Newcomb was appointed to the vacant place. He immediately 
formed the grandiose scheme of reforming nearly all the fundamental data 
involved in the construction of an astronomical ephemeris. One would 
have been inclined to predict the failure or, at least, only partial success of 
such a scheme; but Professor Newcomb, by his skillful management, came 
very near to complete success during his lifetime; only tables of the moon 
were lacking to the rounding of the plan. It must, however, be noted that he 
was fortunate in finding a few men ready to hand in relieving him not only of 
