F. A. Ferret — Lava Eruption of Stromboli. 461 



there were large conglomerate bowlders, consisting mainly of 

 old altered lava masses cemented together by fresh lava. Both 

 of these explosions, but especially the second, threw out a large 

 quantity of free augite crystals, many in the form of the well 

 known cruciform twins. 



This first explosion, which was heard at Lipari, was followed, 

 at 9.30, by a weaker one. The main explosion was also fol- 

 lowed, as is generally the case, by a succession of puffs which 



Fig. 10. 



Fig. 10. Large conglomerate bowlder (about one cubic meter) ejected by 

 the explosion of Nov. 26th. 



are comparatively so unimportant as to be noticed only as con- 

 tributing to the maintenance of the great ash "pino" and the 

 enlargement of its base. 



The second great explosion, on Nov. 26, was much more pro- 

 found, and was preceded by a strong concussion which violently 

 shook the windows of the town from half a minute to a minute 

 before the sound of the explosion itself reached it. We have 

 here a phenomenon, also observed at other volcanoes, which 

 requires further study before a satisfactory explanation can be 

 reached, the difficulty here being the greater because of the 

 uncertainty as to the elapsed time between concussion and 

 explosion. No windows were broken, but the flat roofs were 

 made to leak. 



