DERIVATION OF THE TERRESTRIAL SPHEROID FROM 

 THE RHOMBIC DODECAHEDRON 



Two papers have recently been published which tend to 

 again awaken special interest in the theme of the grand plan 

 of the earth. One is the presidential address of Professor B. K. 

 Emerson on the "Tetrahedral Earth and the Zone of the Inter- 

 continental Seas," delivered before the Geological Society of 

 America; and the other is a lecture before the Royal Geographi- 

 cal Society by Dr. J. W. Gregory, on the " Plan of the Earth and 

 Its Causes." 



Both papers are an explanation and discussion of the quaint 

 and suggestive conception of the tetrahedral form of the earth 

 as advanced by William Lothian Green, an English merchant of 

 Honolulu, an original thinker of no mean astuteness, who, in his 

 Vestiges of the Molten Globe? presents a hypothesis which can be, 

 by no unbiased student, regarded as lying entirely within the 

 fanciful. 



Briefly stated, Green's hypothesis is that on the theory of a 

 cooling globe, a noticeably angular or ridged form would result. 

 As the sphere is the solid which contains the maximum volume 

 under a given surface, so the geometrical form having the mini- 

 mum volume under the same surface is the tetrahedron. Hence, 

 the contracting globe would tend to assume the tetrahedral 

 shape, as one permitting the greatest reduction of bulk with the 

 least amount of change of surface. 



Green takes as his fundamental form the hexatetrahedron 

 with curved faces, as most nearly approaching the sphere. In 

 the development of the hemihedral form of the hexatetrahedron 

 the original faces retained give rise to one set of obtusely 

 pointed pyramids ; and the extended portions of the faces a 

 second set of pyramids having more acute apices. The former 

 represent the water areas of the globe and the latter the land 



"Vestiges of the Molten Globe, Pt. I, London, 1875; Pt. II, Honolulu, 1887. 



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