DERIVATION OF THE TERRESTRIAL SPHEROID 245 



areas. There are then three triangles of water with their bases 

 against a land triangle around the south pole, pointed north- 

 ward and interlocked with three great southward-pointing land 

 triangles, having their bases against the north polar triangle of 

 water. Thus is explained the plan of the earth as indicated by 

 its grandest geographic features. 



The idea of a tetrahedral earth did not first originate with 

 Green, though it was doubtless original with him. Neither is the 

 attempt to reduce the earth to a faceted body unusual. From 

 the time of Elie de Beaumont, more or less intense interest has 

 been taken in the subject. 



The distinctly tetrahedral conception has been, as Professor 

 Emerson has noted, discussed by a number of writers. Richard 

 Owen, 1 of New Harmon)-, Indiana, and brother of Dr. David 

 Dale Owen, compared the form of the earth to the crystal of 

 diamond. Besides Green, already mentioned, Michel-Levy 2 has 

 lately formulated his tetrahedral idea of the earth. Still more 

 recently Gregory 3 has considered the subject much along the 

 same lines as the writer last mentioned. 



In comparing Green s tetrahedron with that projected by 

 Michel- Levy it may be noted that the obtuse pyramids of the 

 former correspond very nearly to the sharp pyramids of the latter. 



Now, the main object of the present note is to call attention 

 to the fact that in all of these more recent attempts to reduce 

 the earth to regular geometrical form there is an important sug- 

 gestion that appears to have escaped notice. This is embodied 

 in a short paper which appeared in the American Meteorological 

 Journal for 1888, 4 under the title of the "Probable Derivation of 

 the Terrestrial Spheroid from the Rhombic Dodecahedron." 

 It is by the same Richard Owen who earlier gave expression to 

 many of the facts and fancies connected with the idea of the 

 tetrahedral earth. 



1 Key to the Geology of the Globe, p. 60, 1857. 



2 Bull. Geol. Soc. France, T. XXVI, p. 105, 1898. 

 3 Geographical Journal, Vol. XIII, p. 225, 189Q. 



4 Am. Meteorological Jour., Vol. V, p. 289, 1888. 



