GEOLOGY. 



629 



Astonished at the grandeur and variety of volcanic phe- 

 nomena, the learned of all ages have sought to explain the 

 mystery of their origin. Numerous hypotheses have been 

 put forward for this purpose, and have successively fallen 

 into oblivion. We shall mention only some of the most 

 celebrated. 



235. Pimtludus Cyclopum, ejected from volcanoes. 



During the era of the encyclopaedists, in the eighteenth 

 century, when all kinds of audacious theories were put for- 

 ward, volcanoes were explained very variously. One of the 

 ideas then most in vogue was that they only resulted from 

 the ignition of a mass of coal and pyrites which happened 

 to be in the strata of the mountain in question. 



Lemery, the chemist, proposed another hypothesis. In his 

 experiments in the laboratory he had produced a sort of 



