STRUCTURE AND MODE OF ACTION 



OF 



VOLCANOS, 



IN DIFFERENT FARM OF THE GLOBE. 



(This dissertation was read in a public assembly of the Academy at 

 Berlin, on the 24th of January, 1823.] 



WHEN we reflect on the influence which, for some centuries 

 past, the progress of geography and the multiplication of 

 distant voyages and travels have exercised on the study of 

 nature, we are not long in perceiving how different tin's in- 

 fluence has been, according as the researches were directed to 

 organic forms on the one hand, or on the other to the study 

 of the inanimate substances of which the earth is composed 

 to the knowledge of rocks, their relative ages, and their origin. 

 Different forms of plants and animals enliven the surface of 

 the earth in every zone, whether the temperature of the 

 atmosphere varies in accordance with the latitude and with 

 the many inflections of the isothermal lines on plains but 



