F. A. Ferret — Lava Fountains of Kilauea. 147 



Returning to the Kilauea lake we see that very small foun- 

 tains play over all portions of the surface where the resistance 

 of the crust is low, as in the "bright lines." They are evi- 

 dently caused by the coalescence, below the surface, of small 

 gas vesicles into larger ones with greater tension and ascen- 

 sional power. This action is automatic and small quantities of 



Fig. 7. 



Fig. 



Etna 1910. Permanence of gas sources on flowing: lava. 



the active lava, isolated from the lake, continue to show all its 

 phenomena until liquidity ceases from loss of heat, even the 

 pahoehoe streams which overflow the rim of the lake continu- 

 ing to show tiny fountains upon their surface until it cools 

 over. 



The so-called " travelling fountains " are due to the circula- 

 tion of the lava, in spite of which three or four large fountains 



