58 HISTORY OF ASTRONOMY. 



several months. The planet was finally discovered by 

 De Zach on the 31st of December, and by Olbers on the 

 following evening. Piazzi conferred on it the name of 

 Ceres, in allusion to the titular goddess of Sicily, the 

 island in which it was discovered; and the sickle has 

 been appropriately chosen for its symbol of designation. 

 The mean distance of Ceres, as determined by the cal- 

 culations of Gauss, was 2*767. The distance assigned by 

 Bode's law was 2*8. In this respect, therefore, the newly- 

 discovered planet harmonized with the other bodies of 

 the system to which it belonged. The new planet was, 

 however, excessively minute ; its diameter, according to 

 Herschel's measurements, amounting to only 161 miles. 

 Its inclination to the ecliptic exceeded ten degrees, and 

 consequently it deviated from that plane more than either 

 of the older planets. 



The discovery of Piazzi was soon followed by another 

 of a similar nature. Dr. Olbers, while engaged in 

 searching for Ceres, had studied with minute attention 

 the various configurations of all the small stars lying 

 near her path. On the 28th of March, 1802, after ob- 

 serving the planet, he swept over the north wing of 

 Virgo with an instrument termed a " Comet Seeker," 

 and was astonished to find a star of the seventh magni- 

 tude, forming an equilateral triangle with two other small 

 stars, whose positions were given in Bode's catalogue, 

 where he was certain no star was visible in January and 

 February preceding. In the course of less than three 

 hours he found the right, ascension had diminished, and 



