384 COSMOS. 



volcano of Bourbon, which Hubert describes as emitting, 

 nearly every year, two streams of lava which frequently ex- 

 tend to the sea, is, according to Berth's measurement, 8000 

 feet high. 77 It exhibits several cones of eruption which have 

 received distinct names, and which alternately send forth 

 eruptions. The eruptions from the summit are infrequent. 

 The lavas contain glassy feld-spar, and are therefore rather 

 trachytic than basaltic. The shower of ashes frequently con- 

 tains olivine in long, fine threads, a phenomenon which like- 

 wise occurs at the volcano of Owhyhee. A violent eruption 

 of these glassy threads, covering the whole island of Bour- 

 bori, occurred in the year 1821. 



All that we know of the great neighbouring terra incog- 

 nita of Madagascar is the extensive dispersion of pumice at 

 Tintingue, opposite the French island of St. Marie, and the 

 occurrence of basalt, to the south of the bay of Diego Suarez, 

 near the northernmost Cap d'Ambre, surrounded by granite 

 aud gneiss. The southern central-ridge of the Ambohist- 

 raene Mountains is calculated (though with little certainty) 

 at about 11,000 feet. Westward of Madagascar, in the 

 northern outlet of the Mozambique Channel, the largest 

 of the Comoro Islands has a burning volcano (Darwin, 

 Coral Reefs, p. 122). 



The small volcanic island of St. Paul (38 38'), south of 

 Amsterdam, is considered volcanic, not only on account of 

 its form, which strongly reminds one of that of Santorin, 

 Barren Island, and Deception Island, in the group of the 

 New Shetland Isles, but likewise on account of the repeat- 

 edly ob&erved eruptions of fire and vapour in modern times. 

 The very characteristic drawing given by Yalentyn in hia 

 work on the Banda Islands, relative to the expedition of 

 Willein de Vlaming (November 1696) corresponds exactly, 

 as do also the statements of the latitudes, with the repre- 

 sentations in the atlas of Macartney's expedition, and Cap- 

 tain Blackwood's survey (1842). The crater-shaped, circular 

 bay, nearly an English mile across, is everywhere surrounded 

 by precipitate rocks which fall perpendicularly in the in- 

 terior, with the exception of a narrow opening, through 

 which the sea enters at flood-tide ; while those which form 



77 Bory de St. Vincent, Voyage aux Quatre Isles d'Afrique, t. iL 

 p. 429. 



