XXXIX 



the last rays of the sua falling on some layers of vapour collected in the 

 upper regions of the atmosphere. He showed that these vapours, them- 

 selves characteristic of fine weather, are formed by actual particles of 

 dust &c, whether mineral or organic, suspended in the air, where they 

 float when dry, falling to the ground when made heavy by moisture. 

 When abundant they cause a haziness of the atmosphere, when in small 

 quantity the clearness of the atmosphere returns. 



Even the insects fluttering about obey this law. If swallows skim the 

 ground at the approach of rain and reascend in fine weather, it is because 

 in the first case the insects charged with damp cannot rise, and in the 

 second case are relieved from this weight and mount high up in the air. 



A. de la Rive took a deep interest in political questions. He was 

 always liberal in his views, but at the same time determined to resist 

 extreme democracy. 



After the revolution of Geneva, at the period of the war of the Son- 

 derbund, he resigned his professorship and gave up public life. He 

 was, however, on the occasion of the annexation of Savoy to France, 

 appointed to watch over the interests of the He]vetic Confederation in 

 London. He was received with great distinction by the Queen, and on 

 his return made one of the Assembly elected to revise the constitution 

 of Geneva. After this work was accomplished he retired entirely from 

 public affairs. 



In the spring of 1873 he was attacked with paralysis, but was, never- 

 theless, able to read in a feeble voice on June 5th his annual report to 

 the Societe de Physique et d'Histoire Naturelle. In the November 

 following he had a severe stroke of paralysis on his way to Cannes, but 

 managed to reach Marseilles, where he died on the 27th. 



His wife only survived him a few days. 



De la Rive's principal work was the ' Traite d'Electricite Thcorique et 

 Appliquee,' in three volumes, which appeared between the years 1854 

 and 1858, in which he published his theory of the Aurora Borealis, first 

 brought forward in 1854, and illustrated by the experiment now well 

 known to physicists of rotating the voltaic arc of light around the pole 

 of a magnet, as any other ponderable conductor would rotate. • This 

 work was published simultaneously in France and England. 



During a period of fifty years he made many contributions to Science, 

 which were published in the ' Memoires de la Societe de Physique et 

 d'Histoire Universelle de Geneve ' or in the ' Bibliotheque Universelle.' 

 Erom 1836 to 1845 he edited the literary and scientific parts of the 

 ' Bibliotheque Universelle,' which were then united. He compiled alone, 

 as supplementary to it, the ' Archives de l'Electricite,' in five volumes, 

 1841 to 1845, and conjointly with De Marignac and others the 

 ' Archives des Sciences Physiques et Naturelles/ in thirty-six volumes, 

 1846 to 1857, and the ' Nouvelle Periode ' of the same Recueil, in nine 

 volumes, 1858 to 1860. He was also the author of numerous biographies 



