T. A. Jaggar — Initial Stages of the Spine on Pelee. 35 



crossing the west side of the base of the cone obliquely from 

 south to north upwards. The glow increased and diminished 

 visibly, and on one occasion a sudden increase was followed by a 

 rumbling sound. 



Mention has been made of the scaly appearance of the frag- 

 ments on the slope of the cone. They appeared quite similar 

 to the "bread-crust" bomb from Pelee figured in the accom- 

 panying photograph (fig. 1). This bomb has the specific 



Bomb from Mt. Pelee. 

 (Scales shown are inches and centimeters.) 



gravity of andesite, shows a brecciated composition, is semi- 

 vitreous on the outer surfaces, and is uniformly cracked in 

 deep gashes (4 inches). This structure seems to indicate that 

 the outer portion of the block has been plastic, while the 

 interior remained a solid rock. Other similar fragments, less 

 deeply fissured, may be found on the slopes of Pelee and 

 Soufriere, and these are not hardened spheres of molten lava, 

 but angular pieces of old volcanic rocks. The presence of 

 pumice among the products of Pelee's eruptions does not of 

 necessity imply anew lava; much of the ancient material is 

 pumiceous. These bread-crust bombs, however, are not made 

 of pumice, but consist of hard crystalline andesite, frequently 

 containing inclusions. 



