166 CARNEGIE INSTITUTION OF WASHINGTON. 



the valley which was not there before the outbreak took place. It 

 is, however, clear from a study of the terrane that this material did 

 not find its way from the main vent to its present location, either tlirough 

 the air or by any form of flow. The only conclusion, therefore, 

 a,ppears to be that the bottom of the valley itself must have been 

 fractured and that the major portion of the material now found must 

 have been forced up through one or more openings in the valley floor. 

 Dr. Fenner's observations also indicate that the material must have 

 advanced through the valley while still hot enough to consume trees, 

 and must therefore have been a dry flow rather than a mud flow, 

 perhaps with something of the physical texture of dry sand more or 

 less charged with gas and loaded with coarser fragments and pumice. 

 It possesses none of the characteristics of a fluid or semi-fluid lava 

 stream. 



Similarly, the origin of the fumaroles has been a matter of some 

 doubt ; neither their gas-content nor their wide distribution had at first 

 suggested that they could be the result of primary activity. On the 

 other hand, if they are secondary, their long duration indicates a very 

 unusual supply of heat from an, as yet, undetermined source. The 

 valley is obviously the drainage-basin for a mountainous area in which 

 the rainfall is very large and the prevailing temperature throughout the 

 year is low. There is no essential difficulty in accounting for the water- 

 content of the fumaroles, but it may fairly be presumed that so exten- 

 sive a fumarole area, persisting with practically undiminished intensity 

 for a period of eight years, would require a very much greater or more 

 intense source of heat than would be afforded by cooling ejecta, even 

 in great mass. These apparent anomalies contribute to the problem 

 very unusual features compared with any other fumarole area known 

 to geologists, and the results of the intensive studies now being made 

 in the laboratory of all the material collected there, both gases and 

 solids, will be awaited with unusual interest. 



Brief reviews of the papers published by members of the Labora- 

 tory staff during the current year follow : 



PUBLICATIONS. 



(1) The term "inversion." J. B. Ferguson. Science, 50, 544-546 (1919). 



The diversity among the phenomena which are referred to by the name 

 "inversion" is so great that at present the word has lost any precise meaning 

 which it may have had in the past. In this paper the suggestion is made that 

 inorganic chemists confine the word inversion to solid single-phase phenomena, 

 such as the change of rhombic to monoclinic sulphur, and the term transition 

 to phenomena such as an incongruent melting, instead of the present synony- 

 mous use of these terms for all these phenomena. 



(2) Polarized light in the study of ores and metals. Fred. E. Wright. Proc. Am. Phil. 



Soc, 58, 401-447(1919). 



In this paper the attemi)t has been made to pi-esent in connected form the 

 electromagnetic theory of the reflection of light from absorbing media, and 



