28 HISTOKY OF ASTEOKOMY. 



stars contained in this precious collection, there was 

 only one which could be presumed to have been the 

 planet, and this observation the author had marked as 

 doubtful! Thus the question stood astronomers were 

 afraid to admit, and still could not reject the conclusions 

 of Mr. "Walker. The steamer which left Boston on the 

 1st of March, carried a copy of the Boston Courier, con- 

 taining the account of Mr. Walker's researches. This 

 paper was destined for M. Le Yerrier ; and, on the very 

 day of its arrival, he also received a letter from Altona, 

 dated March 21st, announcing that M. Peteraen 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 discovery, theoretically, February 2d ; 

 and it was confirmed by an actual inspection of the 

 heavens, February 4th. Mr. Walker, then, has the pri- 

 ority of six weeJcs in the discovery. Fortunately, the 

 original manuscripts of Lalande had been preserved, and 

 were deposited in the observatory of Paris. On con- 

 sulting them it was found that the doubtful mark ap- 

 pended to the published observations, did not exist in 

 the manuscript. Moreover, the star had been twice ob- 

 served, viz., on the 8th and 10th of May, 1795 ; but as 

 the two observations did not agree, Lalande suppressed 

 the former, and in his printed book marked the latter 

 doubtful. The discrepancy between the two observa- 

 tions is almost exactly that which is due to two days' 



