520 T. C. CHAMBERLIN 
earth with internal qualities closely like those of the accessible 
parts of the present body, and the working tenets that spring from 
this hypothesis most naturally are those founded on crystalline 
structure dominated by elastico-rigid properties. The conception 
is free from the inheritances of a liquid state with its inevitable 
assortments and systematic arrangements of material on the basis 
of specific gravity. 
The conceptions of internal temperature and of vulcanism 
associated with this hypothesis by its author’ are peculiarly hospi- 
table to the development and maintenance of a solid crystalline state 
of the interior. They are relatively free from the postulate of very 
high temperatures. No occasion for a rise to the critical tempera- 
tures of rock-substance is offered and the dilemmas these bring do 
not trammel the problems of the planetesimal earth of the author. 
It is immune against the gaseous heart. The very mechanism of its 
vulcanism automatically forces to the surface the expansional fac- 
tors that contribute to liquefaction and the gaseous state. The 
elements that, if retained, would lend mobility to its mass continu- 
ally seek the surface, while those that contribute to stability and 
solidity remain within. The normal earth-habit under this 
hypothesis is conducive to a stable crystalline organization. This 
holds to as great depths as known methods of action may be safely 
projected. As balanced pressure contributes to solidity, it is a 
hazardous assumption that places narrow limits to the downward 
extent of solidity and the crystalline state. 
Deep differentiations of specific gravity of moderate degree are 
natural results of a slow planetesimal growth under the conditions 
imposed by the early atmosphere and hydrosphere, in addition to 
the inequalities of infall. The inevitable deformations and grada- 
tional processes of the growing stages are presumed to have empha- 
sized these inequalities, in certain respects, in modes of the same sort 
as those that affected all later history. These inherited inequalities 
of specific gravity are, perhaps more than any other agency, the 
governing power in shaping if not actuating diastrophic movements. 
This is the basis on which isostasy today does whatever it is com- 
petent to do toward a final equilibrium. How such a basis for 
«“The Bearings of Radioactivity on Geology,” Jour. Geol., XIX, No.8 (1911). 
