1 10 Analysis., ^-c. of Cordier"'s Essay upon the 



" This opinion of a central fire slept, till it became obscurely 

 revived by Des Cartes, Halley, Mairan, Buffon, and others ; to 

 whom it was suggested by some or all of the following conside- 

 rations : 



" The figure of the earth ; a globe flattened at the poles ; 

 pointing to an originally fluid state as necessary to produce it by 

 revolutionary motion. 



" Certain astronomical phenomena. 



" The mobility of the central mass, producing magnetic action. 



" The difference of temperature at the surface and at small 

 depths. 



" Experiments on the cooling of incandescent bodies. 



" These considerations, however, failed to produce general 

 conviction ; and the aqueous fluidity of the globe, a theory ad- 

 vanced by Pallas, Dessaussure, Werner and his disciples, obtain- 

 ed the ascendancy in public opinion. This theory supposes the 

 aqueous liquidity of the whole matter composing the globe of the 

 earth, and its gradual solidification, one stratum after another, 

 from the centre to the surface, by crystallization in water ; vol- 

 canos being nothing more than the accidental results of peculiar 

 localities. 



" This (Neptunian) theory of Werner, has been losing ground 

 from the close of the last century to the present time. It may 

 now be considered as universally abandoned." 



It has been found, especially, that the substances ranked 

 by Werner under the denomination of floetz-trap, have so 

 strong an analogy in their appearance, their composition, 

 mechanical and chemical, their position covering indiscrimi- 

 nately all kind of strata, and other circumstances, with 

 known ejections from volcanos, that their igneous formation 

 hardly admits of doubt. That these layers, strata and irreg- 

 ular masses formed over rocks of every age and formation, 

 are often traceable to manifest craters of extinct volcanos ; 

 and have, in other cases, so many analogies with known 

 volcanic ejections, that the conclusions as to their igneous 

 nature are nearly irresistible. 



" In aid of this last and modern theory, (the Plutonian,) come 

 the experiments on the radiation of caloric into atmospheric 

 space ; the communication of caloric from molecule to molecule ; 

 and certain mathematical considerations of a general nature ; as 

 well as the small distance to which solar heat penetrates into the 

 surface of the earth ; and the depth where a fixed temperature 

 has been constantly observed. Late experiments also have shewn, 



