234 



THE NATIONAL GEOGRAPHIC MAGAZINE 



Photograph by E. G. Zies 

 DROPPING THE THERMOCOUPLE INTO A DEEP HOPE 



Photograph by Frank I. Jones 



CHEMISTS PREPARING TO COLLECT THE GAS PROM ONE OF THE FUMAROPES 



A complete knowledge of the gases given off by the fumaroles could not fail to add greatly 

 to our understanding of the problems of volcanism. 



