On the 28th of November, 1809, he presented to the Academy of Turin a 

 paper, entitled "Equation de la courbe formee par une lame elastique 

 quelles que soient les forces qui agissent sur la lame," the first of a series 

 of papers offered to the same Academy, far too numerous to be recorded in 

 the present notice. On the 15th of March, 1811, on the recommendation 

 of Lagrange, he obtained the Professorship of Astronomy in the Uni- 

 versity of Turin, and on the 5th of March, 1813, became Director of the 

 Observatory. After the Restoration, the king, Victor Emmanuel I., who 

 took a personal interest in the progress of astronomy and frequently sent 

 for Plana to explain various celestial phenomena, augmented the income of 

 the Observatory, and transferred it from the house of the Academy to a 

 better situation on the west tower of the north face of the Palazzo Ma- 

 dama. During the years 1821, 1822, 1823 he was associated with Carlini 

 in the operation of measuring an arc of parallel in Savoy and Piedmont. 

 The results were published in 1825, under the title "Observations geode- 

 siques et astronomiques pour la mesure d'un arc de parallele moyen." In 

 1828 the authors received from the Institute the Lalande prize for the 

 astronomical part of their joint work. In 1832 he published his ' Theorie 

 du mouvement de la Lune,' in three large quarto volumes. This he re- 

 garded as the most important of all the labours of his life. For this work 

 the Copley Medal was awarded to him in 1834, and the Gold Medal of 

 the Astronomical Society in 1840. In announcing the latter award, Sir 

 John Herschel, President of the Society, made the following quotation 

 from the " Discours preliminaire " of the ' Theorie de la Lune' "Je 

 n'ai pu me faire aider par personne ; j'ai du traverser seul cette longue 

 chame des calculs, et il n'est pas etonnant si, par inadvertence, j'ai omis 

 quelques termes qu'il fallait introduire pour me conformer a la rigueur de 

 mes propres principes," adding, " When we look at the work itself there 

 seems something awful in this announcement." 



In 1822, on the occasion of the appearance of his " Mdmoire sur les 

 mouvements des fluides qui recouvrent une sphero'ide a peu pres spherique," 

 he was elected a Corresponding Member of the Institute, and in 1860 one of 

 the eight Foreign Associates. In December 1851 he became President of 

 the Royal Academy of Turin. He was elected Foreign Member of the 

 Royal Society in 1827. He received from his own king the title of Baron, 

 and was created a Senator on the formation of the Senate in 1848. 



He delighted in the classic poets, and was not more remarkable for the 

 accuracy and elegance of his mathematical investigations than for the pre- 

 cision of his style in writing. He was in the habit, it is said, of bestowing 

 extraordinary care on the composition and correction of his works. 



On the 6th of January, 1864, he read a paper before the Royal Academy 

 of Turin, entitled " Memoire sur les formules du mouvement circulaire, et 

 du mouvement elliptique libre autour d'un point excentrique par 1'action 

 d'une force centrale." This was his last work. He died at Turin on the 

 20th of January, 1864, leaving a widow (Lagrange's niece) and a daughter. 



