Mechanism of Stromboli. 507 



sured sort of rise and fall in its snorting, is red-hot to the lips, which 

 are of hard lava ; and the temperature at the mouth I found, in 1864, 

 was sufficient to melt brass wire, but not sufficient to fuse a similar wire 

 of bronze (i. e. copper with about 5 per cent, of tin). . 



The falling-in of any considerable proportion of the walls of this grand 

 crater, which, on the landward side, consist of nearly horizontal beds of 

 volcanic rock and conglomerate, forming at that side a vast mural preci- 

 pice, though almost wholly of compacted tufa for the remainder of its 

 periphery, would easily give rise to a renewal of volcanic energy, such 

 as nowhere exists now in the Lipari group. 



Stromboli is the next to this in existing energy ; but though the per- 

 sistence and character of its activity excite much more attention, the 

 actual evolution of volcanic heat is greatly inferior to that constantly going 

 on from the unobstructed " bocca " of Vulcano, which, if again obstructed, 

 would produce very violent effects. In Lipari Island we have the traces 

 of several great craters of extreme antiquity, the most recent being that 

 which evolved the mountainous masses of pumice and the enormous 

 stream of pumice and obsidian which falls into the sea at the north-east 

 of the island ; but the greatest sign of present activity is found on the 

 shore at the opposite side of the island, at II Stun, where innumerable jets 

 of hot water and superheated steam with sulphurous acid issue from the 

 heavy beds of trachyte, which they rapidly decompose and convert into 

 clays and hyalite. 



In others of the islands, such as Panaria and Saline, no sign of activity 

 remains, and the most practised eye with difficulty seeks to recover the 

 positions or outlines of the very ancient craters. Lastly, in the small 

 islands of Basiluzzo, in the low rocks of Liscanera and Liscabianca, and 

 in the huge spire of Datola, formed of vertically parted and splintery 

 trachyte of the most obdurate character, we have but the last shreds of 

 one or more great volcanic islands which once occupied the shallow sea- 

 spaces between all these islands, and probably connected them into a 

 single vast cone. A hot spring still rises in water of 4 or 5 fathoms 

 deep between Liscanera and Liscabianca, which possibly mark the site of 

 one of the most' recent of the craters at this spot, the islands which they 

 formed, at a period too distant for imagination, having here almost disap- 

 peared under the eroding influence of the comparatively tranquil and 

 tideless waters of the Mediterranean, aided perhaps by local subsidence, 

 but of which there is little or no evidence. It will thus be seen that the 

 change in position and decadence in energy ascribed to the existing crater 

 of Stromboli, although for 2000 years its energy has seemed to be constant 

 or not greatly diminished, are circumstances in complete accordance with 

 the facts presented generally by the volcanic islands of the whole group. 

 The existing tube of Stromboli, like that which leads to the " bocca " of 

 Yulcano, has but a lateral and indirect and very much choked-up com- 

 munication with those great central ducts which once gave vent to 



