Mechanism of Stromboli. 509 



they would have presented on all their surfaces and edges the more or less 

 rounded outlines and extreme induration and closeness of grain due to 

 long-continued torrifaction, which are the invariable characteristics of such 

 blocks. The true history of these great blocks is, that they had *>een 

 detached by the shakings of the outbursts from one of the steep cliffs of 

 the ancient crater-walls which overhang the crests of the slope, and had 

 thence rolled down to the position in which we found them at about E in 

 Diagram No. 3, which is a section of the slope of debris and of the sea- 

 bottom in line extending from its base. In this line we took a few sound- 

 ings at distances from the water-line at the base of the slope, which we 

 had to guess. These distances, as guessed by me, exceeded those guessed 

 by Colonel Yule, though not very greatly ; and I have preferred to adopt 

 those derived from his military experience in guessing distances by the 

 eye rather than my own. 

 D 



Diagram No 3. 



It will be seen from these soundings that the statements made by the 

 islanders, and wrongly attributed to Captain Smyth (see his ' Sicily ' in 

 loco), that the sea outside Schiarrazza cove is unfathomable, and hence 

 swallows up the debris of more than 2000 years, is wholly erroneous. 

 Indeed Smyth's soundings (' Sicily and its Islands '), as well as the Admiralty 

 Chart, sufficiently indicate that for some miles in the offing here the 

 Mediterranean does not exceed 100 fathoms in depth. The bottom, along 

 which I took these soundings consists of huge irregular and ovoidal 

 masses, of 10 to 20 tons in weight, of volcanic rock, old and water- 

 rounded. What, then, does become of the debris ? Its quantity, in reality, 

 is extremely small in a given time. A very large proportion of it consists 

 of mere dust and glassy or angular lapillae, and these, if blown seaward, 

 fall at a considerable distance away, and are lost in the depths ; those 

 which fall nearer, including the fragments that form the average mass of 



