hy Alexander von Humboldt. xxiii 



It would also be a matter of great importance to get ob- 

 servations respecting terrestrial magnetism, particularly so as 

 to define the position of a given segment of the magnetic equa- 

 tor. Capt. Elliott, as the result of his comprehensive studies, 

 (1846-49), ascertained that the magnetic equator passes through 

 the north end of Borneo, and thence nearly due W. to the 

 northern extremity of Ceylon. In this region the curve of 

 minimum intensity is nearly parallel to the magnetic equator, 

 which intersects the Continent of Africa near Cape Guarda- 

 fui — according to Rochet d'Hericourt, in lat. 10° 7' N., 

 long. 38° 5'. E. Between this point and the Bight of Biafra 

 nothing is known. 



The South Asiatic islands comprise Formosa, the Philip- 

 pines, the Sunda group, and the Moluccas. The great and 

 little Sunda Islands and the Moluccas embrace 109 volcanoes, 

 with fiery eruptions, and 10 what are called mud-volcanoes. 

 This is not a mere estimate, but is the result of an enumera- 

 tion by Junghuhn, who, within the last year (1856), has 

 returned to Java, and thorouglily equipped by M. Pahud, 

 Governor-General of the Indian Netherlands, will be of great 

 assistance to the Imperial Expedition. 



An exact mineralogical determination of the volcanic 

 rocks (trachytes) is unfortunately wanting everywhere. 



The most active volcano of Sumatra is the Gunung Merapi 

 (8980 feet), which must not be confounded with a volcano in 

 Java, of the same name. That of Sumatra was ascended 

 by Dr. L. Horner, and Dr. Korthals in 1834. We may 



