34:4: 



F. A. Ferret — Circulatory System in the 



grotto and, subsiding, produce a lower level in the interior, 

 whereupon the outside lava would flow into the grotto. The 

 peculiar conformation prevented the entrance of anything but 

 surface material, which is denser than the rest of the lake sub- 

 stance, thus producing a still lower interior level and causing a 

 downpouring of the heavy crust and surface lava whose 

 momentum as a freely falling mass w T as increasingly effective 



Fig. 3. 



Fig. 3. Grotto and cavity under Floating Island into which surface-lava 

 was flowing in a continuous cascade. 



in beating down the inner level. The result was a cavity, 

 empty as far down as could be seen from the place of observa- 

 tion on the north brink of the crater, and into which a mag- 

 nificent cascade of lava was freely pouring from either side, 

 the inner walls glowing in full incandescence, the two cascades 

 clashing amid fiery spray, and the whole forming a spectacle 

 the beauty of which can with difficulty be imagined, even by 

 those who are familiar with the sight of active lava. The 

 difference of internal and external level could not have been 

 less than live meters and it may well be that so great a dis- 

 levelling would not be possible without the aid — as suggested 

 by my colleague, Dr. Shepherd — of some aspiration at the 

 lower end of the cavity and which might have resulted from a 

 powerful downflow between the island and the shore, the exist- 



