222 Stevenson Macadam on the Cause of the Phenomena 



On the Cause of the Phenomena exhibited by the Geysers of 

 Iceland. By Stevenson Macadam, Teacher of Chemis- 

 try, Philosophical Institution, Edinburgh. Communicated 

 by the Author. 



In a memoir published in the preceding number of this 

 Journal, I referred to certain remarkable properties possessed 

 by bodies when they assume the spheroidal state ; and gave 

 my reasons for believing that the spheroidicity of matter 

 played an important part in Volcanic Phenomena. In my 

 present paper, which may be regarded as a continuation of 

 the preceding one, I propose to shew that the phenomena 

 presented by the intermittent hot springs of Iceland can be 

 clearly and satisfactorily explained by the laws which regu- 

 late matter in the spheroidal state. 



The characteristic phenomena exhibited by the Geysers, 

 before and during an eruption, have been described by many 

 of our distinguished men of science, and the following brief 

 notice of the mode of action of these springs, which has been 

 compiled from the several treatises published on the subject, 

 will convey an adequate conception of the kind of pheno- 

 mena, for which I now attempt to assign the cause. 



The largest and most remarkable of these springs has been 

 termed the Great Geyser, and from the comparative magni- 

 tude of its eruptions it has claimed the special attention of all 

 observers. We find, therefore, that our store of knowledge 

 regarding it is very ample, while but little is known regard- 

 ing the lesser springs. The phenomena presented by the 

 latter, however, does not differ materially from those of the 

 former ; any dissimilarity which might be adverted to, being 

 merely that of the magnitude, not of the kind of phenomena 

 exhibited. 



Prior to an eruption of the Great Geyser, a hollow rum- 

 bling sound is heard, quickly increasing in loudness, and ac- 

 companied by explosions resembling the distant firing of 

 cannon ; the earth being at the same time slightly shaken. 

 The subterranean explosions, and the tremor of the earth 

 quickly become more violent. In an instant the atmosphere 



