J. W. Judd — On Volcanos. 213 



during the more violent eruptions, when the constant red glow above 

 the mountain testifies to the existence of incandescent materials 

 within the crater, and when abundant streams of lava flow down 

 into the sea, the solidified crust forming the bottom of the crater is 

 temporarily destroyed, we can scarcely doubt. Stromboli, indeed, 

 appears to present, on a smaller scale, precisely the same characters 

 with those seen in the volcano of the He de Bourbon, as described 

 by Bory de St.-Vincent, and in the crater of Kilauea in Hawaii, as 

 described by Dana and other observers. 



That the more violent states of activity in Stromboli coincide with 

 the winter seasons and stormy weather, and its periods of com- 

 parative repose occur during the calms of summer, is established, 

 not only by the universal testimony of the inhabitants, but, as the 

 foregoing accounts will show, by the actual observations of many 

 competent authorities. 



The very graphic accounts which we have quoted of the appear- 

 ances presented by the liquid lava as seen rising and falling in the 

 vent, agitated by whirling movements, and swelling up into vast 

 bubbles which suddenly burst and give off clouds of vapour, are 

 strongly suggestive of the same conditions as exist when any 

 liquid or viscous material is heated, especially in a deep and 

 narrow vessel, over the fire. In such cases, as vapour is being 

 disengaged within the heated mass, the whole is kept in violent agi- 

 tation ; the small bubbles collecting into large ones force the whole 

 mass upwards, and if the heat be not moderated, these bubbles burst 

 on reaching the surface, and scatter the materials with explosive 

 violence. That the lava of volcanos is a fluid mass containing im- 

 prisoned water, which, as it is relieved from pressure, flashes into 

 steam, is now recognized by all geologists. 



That the barometrical condition of the atmosphere must exercise 

 a powerful influence on such a series of operations, as are seen to be 

 going on within the crater of Stromboli, few probably would be 

 bold enough to deny. Whether the notion, which, as we have seen, 

 has prevailed in these islands from the earliest times concerning 

 which history or tradition affords us any record, namely, that the 

 state of the volcano enables the observer to predict the changes of 

 weather, is a totally different question. Until we are able to 

 appeal to an accurate series of meteorological observations, carried 

 on concurrently with others on the condition of the volcano, the 

 question must remain an open one. But every careful observer will 

 willingly subscribe to the words of Spallanzani on the subject : " I 

 should think myself justly to incur the imputation of rashness, 

 should I. venture to deny these facts, without having sufficient 

 reason so to do ; especially as they are so precise, so circumstantial, 

 and said to have been observed upon the spot." 



Stromboli consists, as we have already seen, of an older central 

 cone, composed of trachytes, coated on all sides by thick masses of 

 more recent basaltic lavas and agglomerates (see pp. 11 and 61). 

 As in the case of Vesuvius and many other volcanos, very beautifully 

 crystallized minerals (especially augite), which must have been 

 formed icitMn the vent, are ejected from its crater. 



