Central Heat of the Earth, and Volcanic Phenomena, 131 



metal. After a certain interval, however, the temperature of 

 the platinum falls sufficiently to allow the liquid to wet it, 

 and then, for the first time, the hissing sounds and burst of 

 steam, characteristic of sudden ebullition, are observed. 



In such an experiment as the one just recorded, the condi- 

 tion of the water next the hot metal is the same as that of 

 drops of the same liquid thrown upon a heated surface, and 

 the water is said to assume the spheroidal state in the former, 

 as well as in the latter case, although in the first it does not 

 exhibit itself in a single sphere, or in several perfect spheres. 

 In what follows I shall have occasion to refer to each of these 

 manifestations of spheroidicity. 



Thus much then premised, I shall now proceed to the more 

 immediate object of this paper, viz., — the application of the 

 results of the observations on bodies in the spheroidal state 

 to the physical constitution of the globe. 



I assume that our globe at the present time consists 

 essentially of three distinct portions : — 



\st. A central nucleus in a state of igneous fusion. 



2d, A crust at a comparatively low temperature, the inner 

 side of which is in the spheroidal state. 



Zd. A space between the crust and the central nucleus, 

 possibly filled with vaporised mineral matter. 



The arrangement of these several portions and their con- 

 nection one with another, may be better understood by 

 reference to the constitution of an egg, which bears a strong 

 analogy to it in point of arrangement, though differing in 

 shape. The yolk of the ^^'g represents the mass of matter 

 in a state of igneous fusion ; the white of the g,^^q^, the 

 space between the heated mass and the crust ; and the shell 

 of the Qgg, the crust of the globe. 



When referring to the experiment with the platinum rod, 

 I stated that when it was heated to the required temperature 

 and plunged into water, the liquid did not touch the rod, but 

 was seemingly repelled by it, and that, therefore, a space 

 intervened between the rod and the water. In the proposed 

 theory, I make no difference in point of assumed arrange- 

 ment, but merely the substitution of one kind of matter 

 for another. In the experiment there are the heated rod, the 



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