DALY. — THE NATURE OF VOLC.VNIC ACTION. 49 



Without further noting the divergences of recent views, it is clear that 

 volcanic theory is in a disorganized state. 



There is one patent reason for this conflict of opinion. The Ve- 

 suvian " steam-engine " and the geyser-like Stromboli have dominated 

 European thought. Though living in a wilderness of waters, the bril- 

 liant Englishman in Hawaii, W. L. Green, concluded that water is not 

 an essential agent in vulcanism, for he had lived many years meditat- 

 ing on the dry, or nearly dry, emanation from Kilauea.* Arrhenius, a 

 physical chemist ; Moissan, a synthetic chemist ; Brun, an analytic 

 chemist ; Mallet, a civil engineer ; von Buch, a Wernerian geologist ; 

 von Humboldt, a Wernerian who traveled greatly ; Scrope, who built 

 his philosophy on observations in the limited European field : Stiibel, 

 a specialist in the giant volcanoes of Ecuador ; Tschermak, a mineralo- 

 gist ; Daubree, an experimental geologist ; Dutton, master of geological 

 reconnaissance — each of these, and every other leader in volcanic 

 study has been forced to think in terms of his intellectual environment. 

 Each investigator has approached the many-sided problem with special 

 training and experience, and many vulcanologists have shared the 

 racial subjectivity which finds explosions, earth -.shaking, and other 

 surface events humanly so important as largely to control inductions 

 on the theoretical side. During the last half-century the discovery and 

 study of thousands of plutonic igneous masses have promoted the view 

 that vulcanism is a subsidiary effect of intrusion. This thesis is em- 

 phasized and illustrated in the following pages, wherein the attempt 

 is made to show its agreement with the essential facts known about 

 volcanoes, ancient and modern. 



A general working theory of vulcanism is here outlined. It has 

 taken its full form directly as a result of the writer's studies in the 

 Hawaiian Islands during 1909, but many of the chief conclusions are 

 founded on his field-work in plutonic geology as well as in the geology 

 of many ancient volcanic formations. The effort has been made to 

 cover the more important literature of vulcanism, and as yet no facts 

 therein stated seem to the writer to be irreconcilable with the theory, 

 which, on the other hand, finds strong support in the great body of 

 recorded facts. Many of the essential points in the following argu- 



" "Water in a rainy di.strict gets to the hot rocks in all sorts of ways, about 

 which there need be little mystery. All this steam seems to have no further 

 connection with the forces concerned in the action of the lav;i.s in Kilauea, 

 tliiin the vapors which arise from the body of a hard-worked horse, when a 

 shower of rain ha.s fallen on him, have with the force he exerts in drawing his 

 load." — W. L. Green, Vestiges of the Molten Globe, Part 11., p. S2, Hono- 

 lulu, 1887. 



VOL. XLVII. — 4 



