Biographical Notice of '^. Piazzi. 163 



1789. As soon as every thing was in order, observations were 

 commenced, the results of which were pubhshed in 1792. 



Piazzi immediately occupied himself with forming a new 

 catalogue of stars, the exact position of which appeared to 

 him as the only true basis of astronomy. Fran9ois Lalande, in 

 France ; Cagnoli, in Italy ; de Zach, Heniy, Barry, in Ger- 

 many ; had partially commenced this work, relying upon the 

 position of thirty-six stars which Maskelyne had pointed out 

 to astronomers as fixed points of comparison. Piazzi, on the 

 contrary, was unwilling to confide in a single observation : the 

 slightest inaccuracy on the part of the observer, the smallest 

 imperfection in the instruments, were accidents too probable 

 to render them admissible. He also knew, that if Flamsteed, 

 Mayer and Lemonnier had continued their observations, they 

 would probably have deprived Herschel of the honour of his 

 discovery. These considerations made him return many times 

 to the same star, before he fixed its position, and it was ac- 

 cording to this laborious but exact method that Piazzi finished 

 his first great catalogue, containing 674<8 stars, which was 

 crowned by the Academy of Sciences of France, and which 

 was welcomed by all astronomers. But a more interesting re- 

 sult of this system was the discovery of an eighth planet, which 

 opened the way to new conquests in the heavens. On the 1st 

 of January 1801, Piazzi, in examining the 87th star of the zo- 

 diacal catalogue of Lacaille, between the tail of Aries and 

 Taurus, perceived a star of the 8th magnitude, which he oc- 

 casionally observed. His habit of verifying the observations 

 of the previous day caused him to remark, on the following, a 

 difference in the place of the small star, which he at first took 

 for a comet. He communicated his observations to Oriani, 

 who, observing that this luminous point had not the nebu- 

 losity of comets, and that it remained stationary and retro- 

 graded, in the manner of a planet in a moderately short space, 

 calculated it on the hypothesis of a circular orbit. He was 

 not deceived in his hypothesis, which, confirmed by other 

 astronomers, awarded to Piazzi the honour of the discovery. 

 He gave it the name of Ceres Ferdinandca : Lalande was of 

 opinion that it should be called simply Piazzi. The king of 

 Naples was desirous of celebrating this event by a gold medal, 

 struck with the effigy of the astronomer; but Piazzi, modest 

 in his triumph, requested that the value of the present might 

 be employed in purchasing an equatorial, which was wanting 

 in his observatory. He continued, in the mean time, with 

 perseverance, the works which he had sketched : neither the 

 cares of his great Catalogue, nor the labours which the dis- 

 covery of Ceres had required, nor even a fever whicli under- 



Y 2 mined 



