ZONE OF PLANETS BETWEEN MAES AND JUPITER. 63 



ninth magnitude, in a zone of the heavens extending fif- 

 teen degrees on each side of the equator. Only about 

 two thirds of the charts contemplated in this great under- 

 taking have yet been executed. 



About the year 1830, M. Hencke, an amateur astrono- 

 mer of Driessen, in Germany, commenced a careful sur- 

 vey of the zone of the heavens comprised within the 

 charts published by the Academy of Berlin. He ex- 

 tended those maps by the insertion of smaller stars, and 

 made himself well acquainted with their various configu- 

 rations. After fifteen years his perseverance met with its 

 due reward. On the 8th of December, 1845, while en- 

 gaged in comparing the map of the fourth hour of right 

 ascension with the heavens, he noticed what appeared to 

 be a star of the ninth magnitude, between two others of 

 the same brightness in Taurus, which had not been 

 noted in his previous examinations. Without waiting 

 for any further observations, M. Hencke wrote to Pro- 

 fessors Encke and Schumacher, stating his reasons for 

 supposing that he had detected a new planet. On the 

 14th of December the Berlin astronomers found the 

 stranger in a position where no star was marked on the 

 corresponding chart of the Academy, and the motion was 

 easily perceived the same evening. On this occasion the 

 elements of the orbit were rapidly determined, not by 

 Gauss individually, as on previous occasions of a similar 

 kind, but by a host of young astronomers throughout 

 Europe, who had become familiar with the methods of 

 that illustrious master. The results of their calculations 



