236 HISTORY OF ASTRONOMY. 



been chiefly employed in the reduction of back observa- 

 tions. In 1852 and 1853 he undertook a series of 

 observations on Alpha Lyrae for the determination of 

 its parallax, but the unfavorable state of the weather 

 during the month of December, when the maximum of 

 parallax occurs, frustrated his expectations, and he was 

 compelled to abandon the attempt. Professor Hubbard 

 has contributed to the Astronomical Journal various 

 papers which have secured him a high reputation among 

 astronomers. Among these papers may be mentioned 

 his researches on the great comet of 1843 ; on the orbit 

 of Biela's comet ; on the orbit of the planet Egeria, etc. 



Professor Eeuel Keith graduated at Middlebury Col- 

 lege in 1845, and commenced duty at the observatory in 

 August of the same year. He was immediately assigned 

 to the meridian transit, and up to the present time has 

 given his exclusive attention to that instrument. The 

 published volumes of the observations show the fidelity 

 with which he has discharged the duties assigned to 

 him. 



Professor Sears C. Walker graduated at Harvard Uni- 

 versity in 1825, and was attached to the observatory 

 during the principal part of the year 1846. During 

 this time he was mainly employed in computations 

 respecting the planet Neptune ; in the discussion of the 

 latitude of the observatory; in determining the error 

 of standard thermometers, etc. 



Professor James Ferguson, for many years first assistant 

 in the department of the Coast Survey, became connected 



