44 



Evolution and Distribution of Fishes 



of fragments of pumice, as they were violently ejected from 

 the crater and fell back again into it. The noise made by 

 this hurtling of fragments in the air was remarked upon 

 by several observers, and as I have myself noticed at Strom- 

 boli, is often more striking than the sound of the ex- 

 plosions. The action of this "dust making" mill, as an 

 active volcano undoubtedly is, was well illustrated by the 

 Vesuvian eruption of 1822. Mr. Scrope, who was an eye 

 witness of that eruption, describes how day after day, as 

 the eruption proceeded, the dust particles became finer and 

 finer, till at last they were able to penetrate the finest cracks, 

 finding their way into and filling all locked boxes, drawers 

 and similar receptacles." 



As to its composition Verbeek secured samples, the 

 chemical composition of three of which are subjoined. Says 

 he: "I have in each case rejected the volatile matters and 

 calculated the total to 100." 



The amount of dust discharged must have been enorm- 

 ous. Thus at the climax period on August 27th "on board 

 three vessels the pumice dust fell on deck" in such quanti- 

 ties as to employ the crews for hours in shovelling it from 

 the decks, and in beating it from the sails and rigging. On 

 board the "G. G. Loudon," anchored in Lampong Bay, it 



