198 Memoir of the Life and Writings of M. Piazzi. 



had held out to him the most brilliant offers to bring him to 

 the university of Bologna, he declined them all. 



Beside the astronomical observations which we have men- 

 tioned, Piazzi had collected an uninterrupted series of solsti- 

 tial observations, from 1791 to 1816, for the purpose of de- 

 termining the obliquity of the ecliptic. By comparing these 

 with those made in 1750 by Bradley, Mayer, and La Caille, 

 it appears that the obliquity diminished 44" in a century. 



Piazzi had now reached the advanced age of eighty-four 

 years, and he expired at Naples on the 22d July 1826. 



To the observatory of Palermo, of which he was the founder 

 and the ornament, he bequeathed his library and his instru- 

 ments, and he left an annual sum for the support of an ob- 

 server.* 



The following is a list of the writings of M. Piazzi : — 



1. Result of the Calculations of the Observations made at 

 Various Places of the Eclipse on June 3, 1778. In the Phil. 

 Trans, vol. lxxix. 1789, p. 55. 



2. Discourse on Astronomy. Palermo, 1790. 



3. Description of the Royal Observatory of Palermo. Four 

 books in 1792, and other five books in 1794. 



4. On the Discovery of the New Planet Ceres Ferdinandea. 

 Palermo, 1802. 



. 5. Stellarum Inerrantium Positiones. 1803. 



6. Observations on the Obliquity of the Ecliptic. Mem. Soc. 

 Italiana, torn. xi. 1804. 



7. On the Precession of the Equinoxes. Ephem. de Milan, 

 1804. 



8. On the Parallax of some of the Fixed Stars. Mem. Soc. 

 Italiana, torn. xii. 



9. On the Measure of the Tropical Year. Id. torn. xiii. 



10. Researches on the Proper Motions of the Fixed Stars. 

 Mem. de VInst. Nat. Ital. torn. i. 



11. The Metrical System for Sicily. 1812. 



12. Catalogue of the Principal Fixed Stars. 1814. 



13. Lecons oV Astronomie. 1817. 



* This sketch of Piazzi's life has been composed chiefly from an abstract 

 of a Memoir by De Angelis, in the Bull, dcs Sciences, Nov. 1826, p. 339. 



