100 Kotice of Graham Island. 



characterised circus or mural precipice which surrounds the 

 canal of communication or crater of eruption. 



It does not farther appear, from the soundings, that this 

 island is the summit of a cone of eruption with an open crater. 

 Captain Swinburne found, within 20 yards on the western side, 

 18 fathoms soft bottom; and Capt. Smith found, at 100 yards, 

 the island bearing from N. to N. W., from 60 to 64 fathoms ; 

 at 80 yards, the island bearing N. E., 70 to 75 fathoms ; at 

 150 yards, the island bearing E., 62 fathoms, cinders : the 

 soundings continuing the same to the distance of five or six 

 miles ; that is to say, varying from 60 to 70 and 80 fathoms, 

 sand and small gravel. The extent of the action by which 

 this island was elevated from below is uncertain. It is a cu- 

 rious fact, that the tides were higher at that period at Gibral- 

 tar than they were ever known to be ; but the connection of 

 this phenomenon with the elevation of submarine formations 

 requires the evidence of correlative observations. 



Captain Swinburne observed the interior of the crater to be 

 filled with muddy water, violently agitated, dashing up and 

 down, and shooting hot stones and cinders into the air ; and 

 occasionally running into the sea, over the edge of the crater, 

 which was broken down to the level of the sea on the west- 

 south-west side for the space of 10 or 12 yards. This edge he 

 supposed, from these appearances, to be formed of cinders and 

 mud : a supposition which is contradicted by the consideration 

 that an embankment of such materials, and of such slight 

 thickness, could never retain the mass so violently agitated 

 in the interior ; and is farther opposed to the statements of 

 Captain Senhouse and Mr. Osborne. 



The isolation of the volcanic action is also demonstrated by 

 the fact, that the temperature of the sea, within 10 or 12 

 yards of the crater, was only 1° higher than the average ; 

 and to the leeward, in the direction of the current, it was not 

 at all affected, though a mirage played on the island. 



There was at a subsequent period of the eruption, on the 

 south-west side of the island, adjoining the principal crater, 

 a terrific ebullition and agitation of the sea, apparently seated 

 in another canal of communication ; attended by the emission 

 of a dense white steam, and a temperature increased to 190° 

 Fahr. ; and the information has, I believe, since reached the 

 Admiralty, that this crater is now elevated above the level of 

 the waters. De Buch has already pointed out, that the inter- 

 nal action which manifests itself at the surface of the soil or 

 sea by a crater of elevation, may constitute at the same time 

 a permanent volcanic crater beneath; the eruptions of which 



