MAGNETIC OBSERVATIONS. 73 



Western Asia, and of the regions lying south of the Caspian 

 Sea. 



1836. Letter from M. A. de Humboldt to H.R.H. Duke 

 of Sussex, President of the Royal Society of London, on the 

 proper means of improving our knowledge of terrestrial mag- 

 netism by the establishment of magnetic stations and cor- 

 responding observations (April 1836). On the happy results 

 of this appeal, and its influence on the great Antarctic expedi- 

 tion of Sir James Ross, see Cosmos, vol. i, p. 136, and Sir 

 James Ross's Voyage to the Southern and Antarctic Regions 

 1817, 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 British 

 Association at Liverpool, pp. 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 

 made there from 1840 to 1846 (see Transact, of the Royal 

 Irish Academy, vol. xxii. pt. i, pp. 74 96). 



1837. Sir David Brewster, A Treatise on Magnetism, 

 pp. 185-263. 



1837 1842. Sir Edward Belcher's voyage to Singapore, 

 the Chinese Seas, and the western coasts of America (Phil. 

 Transact, for 1843, pt. ii, pp. 113, 140142). These observa- 

 tions of inclination, when compared with my own, which 

 were made at an earlier date, show a very unequal advance 

 of the curves. Thus, for instance, in 1803, I found the in- 

 clinations at Acapulco, Guayaquil, and Callao de Lima to be 

 + 38 48', + 1042/and 9 54'; while Sir Edward Belcher 

 found + 37 57', + 9 1', and 9 54'. Can the frequent 

 earthquakes upon the Peruvian coasts exert a local influence 

 upon the phenomena, which depend upon magnetic force 

 of the earth ? 



18381842. Charles Wilkes's Narrative of the United 

 States' Exploring Expedition, vol. i, p. xxi. 



1838. Lieutenant James Sullivan's Voyage from Falmouth 

 to the Falkland Islands (Phil. Transact, for 1840, pt. i, pp. 

 129, 140143). 



1838 and 1839. The establishment of magnetic stations 

 under the admirable superintendence of General Sabine in 

 both hemispheres at the expense of the British Government. 



