72 cosmos. 



mortal work on " the general theory of terrestrial magnet- 

 ism" (see Results of the Observations of the Magnetic As- 

 sociation in the year 1838, edited by Gauss and Weber, 

 1839, p. 1-57). 



1833. Observations of Barlow on the attraction of the 

 ship's iron, and the means of determining its deflecting ac- 

 tion on the compass ; Investigation of electro-magnetic cur- 

 rents in Terrellas ; Isogonic atlases. (Compare Barlow's 

 Essay on Magnetic Attraction, 1833, p. 89, with Poisson, sur 

 les deviations de la boussole produite par le fer des vaisseaux, in 

 the Mem. de VInstitut, t. xvi., p. 481-555 ; Airy, in the Phil. 

 Transact, for 1839, pt. i., p. 167 ; and for 1843, pt. ii., p. 

 146 ; Sir James Ross, in the Phil. Transact, for 1849, pt. 

 ii., p. 177-195). 



1833. Moser's methods of ascertaining the position and 

 force of the variable magnetic pole (Poggend., Annalen, bd. 

 xxviii., s. 49-296). 



1833. Christie on the Arctic observations of Captain Back, 

 Phil. Transact, for 1836, pt. ii., p. 377. (Compare also his 

 earlier and important treatise in the Phil. Transact, for 1825, 

 pt. i., p. 23.) 



1834. Parrot's expedition to Ararat {Magnetismus, bd. ii., 

 s. 53-64). 



1836. Major Estcourt, in the expedition of Colonel Ches- 

 ney on the Euphrates. A portion of the observations on 

 intensity were lost with the steamer Tigris, which is the 

 more to be regretted, since we are entirely deficient in accu- 

 rate observations of this portion of the interior of Western 

 Asia, and of the regions lying south of the Caspian Sea. 



1836. Letter from M. A. de Humboldt to his Royal High- 

 ness Duke of Sussex, President of the Royal Society of 

 London, on the proper means of improving our knowledge 

 of terrestrial magnetism by the establishment of magnetic 

 stations and corresponding observations (April, 1836). On 

 the happy results of this appeal, and its influence on the 

 great Antarctic expedition of Sir James Ross, see Cosmos, 

 vol. i., p. 192, and Sir James Ross's Voyage to the Southern 

 and Antarctic Regions, 1847, vol. i., pt. xii. 



1837. Sabine, On the Variations of the Magnetic Intensity 

 of the Earth, in the Report of the Seventh Meeting of the Brit- 

 ish Association at Liverpool, p. 1-85 : the most complete work 

 of the kind. 



1837-1838. Erection of a magnetic observatory at Dub- 

 lin, by Professor Humphrey Lloyd. On the observations 



