DERIVATION OF THE TERRESTRIAL SPHEROID 247 



each face would be of the most general form — that is, with six 

 facets — curved after the manner of the diamond. 



But while the natural tendency, in a collapsing shell, may 

 be to assume a form affording the least change of the surface, 

 extraneous conditions might impose slight modifications in other 

 directions. The resultant form might then be a closely similar 

 shape, having the same symmetry. As related to the hexatetra- 

 hedron, the rhombic dodecahedron is one of these forms. And 

 Owen's scheme may more nearly correspond with observed 

 facts than any plan based upon the strictly tetrahedral con- 

 ception. 



In any case, we should expect to have the great world ridges 

 follow approximately the geometrical edges of whatever form is 

 selected. In the central portions of the faces we should expect 

 to find, on the whole, marked depressions. If these features are 

 to be regarded as essential criteria, then Owen's scheme appears 

 to offer fewer objections than any yet suggested. In these con- 

 siderations the hydrosphere may be practically neglected. 



The rhombic dodecahedron is a schematic form to which the 

 great features of the earth are capable of even more exact adjust- 

 ment than that proposed by Owen. If the dodecahedron be 

 oriented so that one of its axes coincides with the earth's axis of 

 rotation, the ends of the other two axes may be made to inter- 

 sect the earth's equator where the latter passes through Sumatra, 

 the west coast of Africa, the west shore-line of South America, 

 and the Phcenix Islands, in the central Pacific Ocean. There will 

 then be grouped around the north pole of the earth four rhombic 

 faces as follows : 



1. North American, 



2. European, 



3. Asian, 



4. Bering. 



Around the equator are : 



. 5. Northern Pacific, 



6. Atlantic, 



7. Indian, 



8. Eastern Pacific. 



