164 Biographical Notice ofM. Piazzi. 



mined his health for four years, could for a moment divert him 

 from his studies. The positions assigned by Maskelyne to 

 sevei'al stars were almost immediately mistrusted ; but Piazzi 

 was too much engaged in his researches to think of correcting 

 the works of others. He deputed M. Cacciatore, the most 

 distinguished of his pupils, to compare directly the principal 

 stars \vith the sun. 



This work was not confined to the thirty-six stars of Mas- 

 kelyne ; it contained one hundred and twenty, which served as 

 the basis of the new Catalogue. Piazzi did not finish it until 

 1814?, and it was not without astonishment that he was found 

 to have extended his researches to 7646 stars. Urged by his 

 friends and his pupils, Piazzi occupied himself with preparing 

 several memoirs which he intended for several Academies of 

 which he was a member: he held at the same time some com- 

 missions which the government of Naples had given him; 

 among others, the formation of a metrical code, to establish a 

 uniformity of weights and measures in Sicily. His work was 

 preceded by an Essay, published in 1808, and by Instruc- 

 tions intended for the use of the cures. During the constitu- 

 tional government of the kingdom (in 1812), Piazzi was con- 

 sulted upon a new territorial division, which was decreed by 

 the parliament, according to the report of the astronomers, 

 and has been preserved even since the destruction of the re- 

 presentative government. The comet of 1811 gave Piazzi an 

 opportunity of explaining his ideas upon the nature of these 

 bodies. He did not suppose their formation to be contem- 

 poraneous with that of the planets : he was rather of opinion 

 that they were occasionally formed in the immensity of space, 

 in which they are afterwards dissipated, nearly like those globes 

 and luminous meteors which are generated and disappear in 

 the terrestrial atmosphere. With such opinions, it is not sur- 

 prising that he always attached but little importance to the 

 observing of comets. 



In 1817, Piazzi was called to Naples to examine the plans 

 of the new observatory, founded by Murat, upon the heights 

 of Capo-di-Monte. He introduced many changes, of which 

 he gave an account in a work published a little before his re- 

 turn to Palermo. Succeeded in the immediate direction of 

 this observatory by his pupil Cacciatore, he took an active 

 part in the labour of a commission charged with the public 

 instruction in Sicily, a country which he regarded as a second 

 home, and which he preferred to the brilliant offers made to 

 him by Bonaparte, to draw him to the University of Bologna. 



Piazzi had no less constancy in his affections, than perseve- 

 rance in his studies : he had collected an uninterrupted series 



of 



