262 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



timo.s lioavicr than \vatcr. If these two outlets were connected Avith 

 a common liquid interior the lava column in the higher conduit 

 would he pressing iov discharge at the lower opening, not at the 

 iiigher, and with a pressure of the order of magnitude of a thousand 

 atmospheres ui)on every square inch of its area. Similarly tlie 

 volcanoes of Central America and of the Alaskan peninsula main- 

 tain each its indepeiulent behavior a|)i)arently regardless of what is 

 hai)pening to its neighboi's. So far as the record of field observations 

 goes therefore the number of simultaneous eruptions which have 

 occiiried in neighboring volcanoes in recent time is so small as to 

 leave little room for any other explanation than coincidence. 



If for these several reasons we limit our conception of a volcano 

 to a juirely local j^heuomcnon arising from unusual local conditions, 

 und if we may assume that other observations above outlined ofl'er 

 reasonable ground for the supposition that gases, reacting among 

 themselves, contril)iite materially to the heat necessary to maintain 

 t» snuill lava basin like that at Kilauea in a liquid state, then we have 

 two further steps to take in order to gi^e to this concept a tangible 

 and reasonably indei)endent existence. First Avhere may such an 

 extraordinary phenomenon as a volcano be supposed to take its 

 origin, and second by Avhat means is the indispensable heterogeneity 

 among the gases maintained in consequence of which the reactions 

 occur ? Obviously this is reasoning somewhat beyond any phenomena 

 actually observed, but the underlying region beneath a A'olcano will 

 perhaps never be accessible to direct observation, so that inference 

 from the l)est experience Ave have must be clraAvn upon to complete 

 the ])icturc. 



Before attempting to indicate the direction in which this search 

 leads it will be helpful to consider the phenomena at another volcanic 

 center Avhich Avas active betAA'een 1914 and 1917. I refer to Lassen 

 Peak in California. This volcano is entirely different in its behavior 

 from Kilauea. Instead of an open basin of liquid lava, more or less 

 continuousl}^ actiA'e but rarely overfloAving, here is an explosive 

 volcano Avhich emitted no liquid lava and only once during its four 

 years of activity reached the temperature indicated by red heat. 



The outbreak at Lassen Peak began Avith an explosion in the 

 summit crater in the early spring (May 30, 1914), the first outburst 

 breaking through snoAV of considerable depth. These explosions 

 continued at intervals of four or five days throughout the sununer 

 and autumn, possibly to some extent in the winter season also, but 

 Lassen Peak is over 10.000 feet high and ihe summit during the 

 Avinter season is shrouded in cloud. In May of 1915, almost exactly 

 one year after the initial explosion, came three days of terrific 

 activity, during which the dust cloud reached a height of 25,000 



