SIMON NEWCOMB—STONE. 239 
paring for and directing the expeditions sent by the United States 
to various parts of the world to observe the transits of Venus that 
occurred in 1874 and 1882. Still later he made a careful study of 
the transits of 1761 and 1769, obtaining results agreeing well with 
those obtained from more modern observations. In connection with 
this investigation, after examining the original records, he vindi- 
cated the honesty of the much-maligned Father Hell, who was one of 
the principal observers of the transit of 1761 and was afterwards 
accused of “cooking” his observations. The importance of the 
velocity of light as a means of determining the sun’s distance caused 
him to become interested in Michelson’s experiments, and led him to 
make similar experiments himself. The acurracy secured far ex- 
ceeded that of values previously obtained. Professor Newcomb’s 
discussion of all the determinations of solar parallax given in the 
supplement to the American Ephemeris for 1897 may be considered 
the last word on the subject up to the present time. 
In 1865 Professor Newcomb published an investigation of the 
orbit of Neptune, including tables of its motions. <A similar treatise 
on the motions of Uranus was published in 1873. Both of these 
memoirs appeared in the Smithsonian Contributions to Knowledge. 
Having thus begun the study of the motions of the solar system, on 
taking charge of the Nautical Almanac office, he “deemed it advis- 
able to devote all the force which he could spare to the work of de- 
riving improved values of the fundamental elements and embodying 
them in new tables of celestial motions.” This gigantic purpose he 
lived to see completed so far as the major planets were concerned. 
As the orbits of Neptune and Uranus were the first to receive his 
consideration, so the tables of these planets based upon newly re- 
vised theories were his last contribution to the Astronomical Papers 
before his retirement from the Nautical Almanac office. 
For the solution of the problem of their motions the major planets 
were separated into three divisions: (1) The four inner planets; 
(2) Jupiter and Saturn; (8) Uranus and Neptune. Reserving for 
his own consideration the four inner and the two outer planets, he 
assigned the orbits of Jupiter and Saturn to Dr. G. W. Hill, stipu- 
lating merely that care be taken to make the work of the latter homo- 
geneous with the work on the other major planets; for instance, the 
values of the masses of Jupiter and Saturn to be used were to be 
assigned by Professor Newcomb. In order to obtain an accurate 
determination of the mass of Jupiter, a careful study was made of 
the motions of the asteroid Polyhymnia, the eccentricity and major 
axis of whose orbit are so large that at times it approaches so near 
to Jupiter as to give rise to large perturbations. 
As a supplement to the American Ephemeris for 1897, Professor 
Newcomb published a brief summary entitled “ The Elements of the 
