History of the Discovery of the Planet Neptune. 195 
The case seemed completely made out. But there was a 
weak point in the argument. Lalande had marked his observa- 
tion of the altitude of this star as doubtful. Could we rest the de- 
cision of a question so important upon a bad observation >? How 
unfortunate, that among the 50,000 stars contained in this pre- 
cious collection, there was on/y one which could be presumed to 
have been the planet, and this observation the author had marked 
as doubtful! Thus the question stocd—astronomers were afraid 
to admit, and still could not reject, the conclusions of Mr. Walker. 
The steamer which left Boston on the first of March, carried a 
copy of the Boston Courier, containing the account of Mr. Wal- 
ker’s researches. This paper was destined for M. Le Verrier ; 
and on the very day of its arrival, he also received a letter from 
Altona, dated March 21st, announcing that M. Petersen had dis- 
covered that this very star, observed by Lalande in 1795, was 
now missing from the heavens. M. Petersen’s discovery was 
made on the 17th of March; Mr. Walker made the same dis- 
hus then we have most unexpectedly secured tivo good ob- 
Servations in place of one doubtful one. We can no lenger with- 
hold our full belief. A single elliptic orbit represents with great 
precision, the two observations of Lalande, and all the observa- 
tions of the past year. Let us then compare the predicted orbits 
of Adams and Le Verrier, with the true orbit according to Mr. 
Walker. The comparison stands as follows: 
lie | Adams. | Le Verrier. Ww Walk PT a: 
Ongitude of the perihelion,  - 999° 11’ 234° 45! 48° zl’ 3" 
Longitude of ancendittg node, unknown, 155 («0 ‘a 4 35 
NClination of the orbit, - - unknewn. 6 0 ae | 0 
| Mean longitnde, Jan. 1, 1847, 323° 24! 318 47 32 ; 53 
rue longitude, Jan 1, 1847, - 26 32 327 33 
“ihe acl i a 0 12061 0-10761 0-098577 
] rean distance from the sun, - “154 30°03656 
ime of revolution im years, - 927:323 217-337 164 6181 
} lean daily motion, ee 15-69 16 ae 2155443 
TE - SEE '__ Baad tss37 
oe hy a ag iat 4 
Srconp Serigs, Vol. V, No. 14.—March, 1848. 26 
