128 SKETCH OF THE LIFE AND ACHIEVEMENTS 



him to prepare a political survey of the colonies 

 of South America. In the month of October, 

 the King of Prussia called him to Aix-la- 

 Chapelle, where he remained until the 26th 

 November. From thence he returned to Paris, 

 where he lived for a series of years exclusively 

 engaged in his studies. 



No European city afforded Baron Humboldt 

 greater facility in furtherance of his objects; 

 there he enjoyed immediate intercourse with 

 his celebrated friends and fellow-labourers, 

 Arago, Gay-Lussac, Julian, Cuvier, Valan- 

 ciennes, and others ; Paris being, moreover, at 

 that time, a great intellectual centre. 



In the autumn of 1822, the King of Prussia, 

 on his road to the congress of Verona, met with 

 Alexander von Humboldt, and invited him to 

 accompany him on a tour through Italy, espe- 

 cially to Venice, Rome, and Naples. During 

 that period from November 22nd to De- 

 cember 1st Humboldt ascended Vesuvius three 

 times, in order to repeat his former obser- 

 vations, conducted in August, 1805, in com- 

 pany of Leopold von Buch and Gay-Lussac, and 

 also in order to examine the condition of the 

 borders of the crater after the recent eruption. 



At the beginning of the year 1823 he arrived 

 with the King of Prussia in Berlin, where he 



