194 Memoir of the Life and Writings ofM. Piazzi. 



sophical theses, which appeared too bold for a young religi- 

 ous. From Cremona, to which he now retired, he was 

 called to Rome, where he was nominated reader of Dogmatic 

 Theology of St Andre de la Valle, where he had for a col- 

 league Father Chiaramonte, (Pius VII.) who retained for 

 him, after his elevation to the Papal throne, the same regard 

 which he had acquired for him in the cloister. 



By the advice of Father Jacquier, Piazzi accepted, in 1780, 

 the chair of the higher mathematics in the Academy of Pa- 

 lermo. In this situation he effected a great change in the 

 methods of instruction. He replaced the works of Wolff by 

 more modern systems, and the productions of Locke and Con- 

 dillac, hitherto almost unknown, soon became familiar to the 

 students. By these, and other changes, he contributed, in a 

 high degree, to dispel the darkness which the united influence 

 of the Inquisition and the Jesuits had shed over the classical 

 soil of Sicily. His ardour for fame was here equally conspi- 

 cuous, and he obtained from the Prince of Caramanica, Vice- 

 roy of that island, permission to found an observatory at Pa- 

 lermo, in the palace of the Viceroy. 



In order to procure instruments for this new establishment, 

 he put himself in communication with the most distinguished 

 astronomers of the day, and he formed in Paris, in April 

 1787, a personal acquaintance with Lalande, Jeurat, Bailly, 

 Delambre, and Pingre. Cassini, Mechain, and Legendre, 

 were about to set out to determine the difference of meridians 

 between Paris and Greenwich. Piazzi accompanied them on 

 that mission, and availed himself of the opportunity of visiting 

 England, where he became intimately acquainted with Mas- 

 kelyne, Herschel, and Vince. He studied with attention the 

 methods of observing as practised at Greenwich, and he ob- 

 served there the solar eclipse of 1788, an account of which 

 he published in the Philosophical Transactions, under the 

 title of Results qf Calculations of the Observations made at va- 

 rious places of the Eclipse of the Sun on June 3, 1788. 



Piazzi engaged our countryman Ramsden to construct 

 for him the instruments for his observatory. Strongly im- 

 pressed with the imperfections of the quadrants then in use, 

 he ordered a five feet astronomical circle, with an altitude and 



