332 COSMOS. 



Island, a slender, narrowly-opened ring (S. lat. 62 55'), and 

 Bridgeman's Island, belonging to the South Shetlands group ; 

 both volcanic, with layers of ice, pumice-stone, black ashes, 

 and obsidian ; perpetual eruption of hot vapors (Kendal, 

 Journal of the Geographical Society, vol. ir, 1831, p. 62). In 

 February, 1842, Deception Island was seen to produce flames 

 simultaneously at thirteen points in the ring (Dana, in United 

 States Exploring Expedition, vol. x., p. 548). It is remark- 

 able that, as so many islands in the Atlantic Ocean are vol- 

 canic, neither the entire flat islet of St. Paul* (Penedo de S. 

 Pedro), one degree to the north of the equator ; nor the Falk- 

 lands (with thin quartzose clay-slate), South Georgia or Sand- 

 wich land appear to offer any volcanic rock. On the other 

 hand, a region of the Atlantic Ocean, about 20' to the 

 south of the equator, longitude 22 W., is regarded as the 

 seat of a submarine volcano.f In this vicinity Krusenstern 

 saw black columns of smoke rise out of the sea (19th of May, 

 1806); and in 1836 volcanic ashes, collected at the same 

 point (southeast from the above-mentioned rock of St. Paul) 

 on two occasions, were exhibited to the Asiatic Society of 

 Calcutta. According to very accurate investigations by Daus- 

 sy, singular shocks and agitation of the sea, ascribed to the 

 commotion of the sea-bottom by earthquakes, have been ob- 

 served in this volcanic region, as it is called in the new and 

 beautiful American chart of Lieutenant Samuel Lee (Track 

 of the Surveying Brig Dolphin, 1854), five times between 1747 

 and Krusenstern's circumnavigation of the globe, and seven 

 times from 1806 to 1836. But during the recent expedition 

 of the brig Dolphin (January, 1852), as previously (1838), 

 during Wilkes's exploring expedition, nothing remarkable 

 was observed, although the brig was ordered, " on account of 

 Krusenstern's volcano," to make investigations with the lead 

 between the equator and 7 S. lat., and about 18 to 27 long. 



III. AFRICA. 



It is stated by Captain Allan that the volcano Mongo-ma 

 Leba, in the Cameroon Mountains (4 12 X N. lat.), westward 

 of the mouth of the river of the same name, in the Bight of 



* St. Paul's Rocks. (See Darwin, p. 31-33 and 125.) 



t Daussy on the probable existence of a submarine volcano in the 



Atlantic, in the Comptes rendus de lAcad. des Sciences, t. vi., 1858, p. 



512; Darwin, Volcanic Islands, p. 92; Lee, Cruise of the United States 



Brig Dolphin, p. 2-55, and 61. 



