650 WILLIAM HERBERT HOBBS 



greater, they were snapped off and carried along upon the surface 

 as passengers. Little if any burning resulted, though the snapped 

 stems were sometimes found charred near the fractured surface. 

 This immunity of inflammable objects from combustion when in 

 contact with lava is apt to cause surprise, though simply enough 

 explained by the insulating nature of the non-conducting lava crust. 



The ejectamenta. — The events of the eruption have been so enlarged 

 upon by the fertile imagination of an excited press that the figures 

 given below will doubtless seem to be underestimates. Yet, while 

 it has seldom been practicable to carry out actual measurements, 

 owing to the irregularities of distribution, and in the deeper layers 

 because of the necessity of extensive excavation, it is confidently 

 believed that the figures given are generally within 15 per cent, of 

 the true averages. 



The ejectamenta may be roughly classified into lava fragments, 

 lapilli, and ash. The lava fragments and lapilli, if we except the area 

 above the atrium and hence near to the crater, have been restricted 

 in their distribution to the area northeast of the mountain (see 

 Fig. i), whither they were carried by the wind on the 7th and 

 8th, during the climax of the outburst. In the belt of cities encir- 

 cling the mountain lapilli begin to be observed near Somma, and 

 farther east are found almost throughout the thick deposit. Their 

 southern limit, probably near Terzigno, has not been sought by the 

 writer. 



Section 0} the deposits. — The total maximum thickness of the 

 deposits at Ottaiano and San Giuseppe may shghtly exceed three 

 feet. The deposits consist of a lower layer, a few inches in thickness, 

 made up of black scoriaceous lava fragments, the largest of which 

 are an inch or more in diameter (in the press reports red-hot blocks 

 weighing 200 kilos descended upon the town). This layer is suc- 

 ceeded by gray lapilli mixed with ash, the former decreasing in 

 size more or less uniformly toward the top. The uppermost inch 

 of the deposit shows in great perfection the succession of colors 

 characteristic of the closing stages of an eruption. The dull gray 

 which succeeds the black lower layer, and which constitutes the major 

 portion of the deposits, here changes into the penultimate thin red 

 layer, the sabhia rossa, which was falHng upon the nth and 12th. 



