TERRESTRIAL MAGNETISM. 77 



observations in this part of Western Asia, and generally 

 south of the Caspian. 



1836. Lettre de M. de Humboldt k S. A. R. le Due de 

 Sussex, President de la Soc. Roy. de Londres, sur les 

 moyens propres a perfectionner le connaissance du magne- 

 tisme terrestre par Fetablissement de stations magnetiques 

 et d' observations correspondantes (Avril, 1836). On the 

 happy results of this application, and its influence in 

 contributing towards the great Antarctic Expedition of Sir 

 James Boss, see Kosmos, Bd. i. S. 438 (Engl. p. 421) ; 

 and Sir James Ross's Voyage to the Southern and Antarctic 

 Regions, 1847, Vol. i. p. xii. 



1837. Sabine on the variations of the intensity of the 

 magnetic force of the earth : British Association Reports, 

 Liverpool Meeting, p. 1 85. This is the most complete 

 work which has been published on this branch of the subject. 



1837 1838. Establishment of a magnetic observatory 

 at Dublin by Professor Humphry Lloyd. On the observa- 

 tions made there from 1840 to 1846, see Trans, of the 

 R. LA. Vol. xxii. Pt. i. p. 7496. 



1837. Sir David Brewster : A Treatise on Magnetism, 

 p. 185263. 



1837 1842. Sir Edward Belcher's observations in a 

 voyage to Singapore, the Chinese Seas, and the West Coast 

 of America : Sabine, in the Phil. Trans, for 1843, Pt. ii. p. 

 113, 140, 142. The observations of the inclination viewed 

 in connection with mine in 1803 indicate a very unequal 

 progression in the secular change at different places. I 

 found, for example, the inclinations at Acapulco, Guayaquil, 

 and Callao + 38 48', + 1 42', and - 9 54' ; Sir Edward 

 Beicher, + 37 67', + 9 1', and -9 54'. May the frequent 



