ii8 THE POPULAR SCIEXCE MONTHLY. 



Dr. Gould's account continues, " he was invited to propose a plan 

 for an observatory in connection with the Philadelphia High 

 School, an invitation which he accepted with eagerness. In ac- 

 cordance with his suggestion, the committee in charge of the 

 school imported from Munich the excellent Fraunhofer equato- 

 rial and Ertel meridian circle which, in his hands and those of 

 his accomplished brother, the present director of the observatory, 

 have done so much for astronomy in America not merely by 

 the number of observations made with them, but also by the in- 

 centive which they afforded to the lovers of astronomy in other 

 parts of the country. It is unquestionable that in several in- 

 stances they induced successful efforts for the procurement of 

 similar and even superior apparatus elsewhere." The results of 

 Walker's researches appeared from time to time in the publica- 

 tions of the American Philosophical Society and various journals. 

 It was in 1841 that he may be said to have "earned his spurs" by 

 a paper on the periodical meteors of August and November, which 

 for many years remained the most important memoir on the sub- 

 ject that had appeared. From that time on he is to be ranked 

 among scientific investigators. 



In 1845 Mr. Walker's affairs underwent a revolution. Certain 

 commercial operations turned out disastrously and entirely bereft 

 him of means. The sense of defeat, the loss of luxuries at a time 

 of life when habits have become fixed, together with anxiety for 

 the future, made the blow a hard one. But it revealed to him, 

 and to the world, the extent of his own scientific ability, and 

 opened the way to higher intellectual gratifications, which he 

 quickly learned to appreciate. The Secretary of the Navy offered 

 him a position in the observatory at Washington which he at 

 once accepted. Here, for the first time, the facilities which his 

 special gifts required were at his disposal, and he immediately 

 proceeded to make good use of them. After a short time he gave 

 up his position at the observatory to accept the direction of the 

 longitude department of the Coast Survey an office which he 

 ably filled until his last illness. 



Early in 1847, while engaged in researches upon the then newly 

 discovered planet Neptune, he became convinced that a star ob- 

 served by Lalande in May, 1795, must have been this planet. 

 With the telescope of the Naval Observatory Prof. Hubbard 

 confirmed this conjecture, and astronomers were thus furnished 

 with an observation of Neptune made fifty-two years before, 

 which afforded means for a most accurate determination of the 

 planet's orbit. The American was none too soon to secure pri- 

 ority, for, quite independently, the same important fact was labori- 

 ously hunted down in Europe by Petersen only a few weeks later. 

 Walker now attacked the problem of Neptune's orbit ; Benjamin 



