TETRAHEDRAL FORM 55 



part of the Atlantic, Mediterranean, and Indian Oceans, 

 and partly along three radial lines making angles of 120 

 with each other. This stage may be referred to as that 

 of primary deformation. While the Atlantic and Indian 

 Oceans have been subsequently enlarged by subsidences, 

 the ancient Mediterranean has been to a great extent 

 obliterated, and even replaced, by mountain chains. 

 There have been produced in addition many other frac- 

 tures, subsidences, and elevations, of a less symmetrical 

 character, due to secondary causes, which it is one of the 

 problems of the future to discover. 



A comparison of the earth with a tetrahedron has been 

 made by Mr. Lowthian Green,* and it is impossible not 

 to admit a certain degree of resemblance. Professor 

 Michel Levy has endeavoured to bring the two forms into 

 closer harmony by a readjustment in the position of the 

 supposed tetrahedron, with regard to the earth, and by 

 erecting on each of its faces a hexagonal pyramid ; and 

 M. Bertrand has given us a new tetrahedral theory, 

 which, however, rests on a comparison with a pair of 

 coaxial tetrahedra placed base to base. The original 

 view of Mr. Lowthian Green seems to make the nearest 

 approach to the facts, and is not in absolute discordance 

 with our own explanation ; indeed, if we suppose the 

 tetrahedral deformation to be superposed upon the figure 

 characteristic of our primary stage of deformation, we 

 obtain a very harmonious result : the Pacific Ocean is 

 then already given as one of the faces of the tetrahedron ; 

 if we next take the Arctic Ocean as the second, we obtain 

 the Antarctic continent as the opposite corner or quoin, 

 and the Indian and South Atlantic Oceans as the two 

 other faces, approximately symmetrical with it. The 

 simplest way by which the student may familiarise 



* Lowthian Green, " Vestiges of the Molten Globe," London, 

 1873. 



