TERRESTRIAL MAGNETISM. 67 



statement, and by Mary SomervihVs ingenious experiments, 

 down to the wholly negative results of Riess and Moser, 

 see Sir David Brewster's Treatise on Magnetism, 1837, 

 p. 48. 



18151818, and 18231826. The two voyages of cir- 

 cumnavigation of Otho von Kotzebue; the first in the 

 f Rurik/ the second in the ' Predprijatie/ five years later. 



1817 1848. The series of great scientific naval expedi- 

 tions sent by the French government, and which have been 

 so fruitful in results contributing to the knowledge of terres- 

 trial magnetism ; beginning with Ereycinet, in the ' Ura- 

 nie/ 1819 1820; followed byDuperrey, in the 'Coquille/ 

 18221825; Bougainville, in the 'Thetis/ 18241826 ; 

 Dumont d'Urville, in the 'Astrolabe/ 18261829, and in 

 the Antarctic Regions in the 'Zelee/ 18371840; Jules 

 de Blosseville in India, 1828 (Herbert, Asiatic Researches, 

 Yol. xviii. p. 4 ; Humboldt, Asie centrale, T. iii. p. 468), 

 and in Iceland, 1833 (Lottin, Voyage de la Recherche, 

 1836, p. 376409); du Petit Thouars (with Tessau), in 

 the 'Venus/ 18371839; Le Vaillant, in the 'Bonite/ 

 1836 1837 ; the expedition of the Commission Scientifique 

 du Nord (Lottin, Bravais, Martins, and Siljestrom) to 

 Scandinavia, Lapland, the Feroe Islands, and Spitzbergen, 

 in the corvette 'Recherche/ 18351840; Berard, to the 

 Gulf of Mexico and North America, 1838, and to the 

 Cape of Good Hope and St. Helena in 1842 and 1846, 

 (Sabine, in the Phil. Trans, for 1849, Pt. ii. p. 173) : arid 

 Francis de Castelnau, Voyage dans les parties centrales de 

 TAmerique du Sud, 1847 1850. 



1818 1853. The long series of important expeditions 



sent to the Arctic Seas by the British Government., to which 



r 2 



