Figure oy means of the Pendulum. 45 1 



if we imagine the plateau to be compressed down to that leveL 

 An equipotential surface would be several hundred meters 

 below the surface of the actual ocean, and as much above the 

 mean continental surface. 



The Forties Geometrical Figure. 



It is probably demanding too much at present, to ask the 

 acceptance of the tetrahedral theory of the earth's figure, but 

 in connection with gravity work allow me to call attention to 

 some points of the argument. It is well known that gravity 

 is in excess at island stations. If we admit the tetrahedral 

 system, these ocean areas are really nearer the center of the 

 earth, and hence should show increased gravity while the con- 

 tinental masses would tend to increase the effect still further 

 by elevating the surface of the sea in their immediate vicinity. 

 It has been shown that the attraction of the Himalayas would 

 elevate the surface of the ocean immediately under them by 

 nearly 1000 feet. This would be equivalent to increasing the 

 distance from the earth's center by 1/1 6,000th part of itself 

 and gravity would be diminished by twice this amount, which 

 is a very appreciable quantity. Besides nothing is more in 

 accordance with the action of physical laws than that the 

 earth is contracting in approximately a tetrahedral form. 

 Given a collapsing homogeneous spherical envelope, it will 

 assume that regular shape which most readily disposes of the 

 excess of its surfaces dimensions, or in other words the shape 

 that most easily relieves the tangential strains ; for while the 

 sphere is of all geometrical bodies, the one with a minimum 

 surface for a given capacity, the tetrahedron gives a maximum 

 surface for the same condition. Experiments on iron tubes, 

 on gas bubbles rising in water and on rubber balloons, all tend 

 to bear out the assumption that a homogeneous sphere tends 

 to contract into a tetrahedron. 



These ideas regarding the shrinking nucleus of our globe 

 and the consequent form assumed by the surface are not by 

 any means new. They have long since been formulated by 

 Green and have found favor in France. Mr. Green has even 

 gone so far as to study the land and water areas of the globe, 

 and has succeeded in finding a close correspondence between 

 the actual features and those required by the theory. Africa 

 and. Europe are considered as one continent, and a depression 

 is assumed between Europe and Asia. In point of fact there 

 was a time when a glacial sea existed along the Siberian fron- 

 tier and communicated with the Caspian waters. Admitting 

 also a polar sea and an antarctic continent, both of which seem 

 highly probable; there seem to be. reasons for the acceptance 



