1913-] SEE— ORIGIN OF HIMALAYA MOUNTAINS. 507 



drawn down at various places to any given spheroidal stratum is the same, 

 although its length varies from place to place as the earth's contour varies " 

 (idem., p. 162). 



This subject of the density of the matter Itidden from our view 

 beneath the crust of the earth has also been discussed by the late 

 Professor Henri Poincare, in an address on " French Geodesy," 

 translated by Professor George Bruce Halstead, and published in the 

 Popular Science Monthly for February, 19 13. The eminent French 

 geometer reasons as follows: 



" But these deep-lying rocks we cannot reach exercise from afar their 

 attraction which operates upon the pendulum and deforms the terrestrial 

 spheroid. Geodesy can therefore weigh them from afar, so to speak, and 

 tell us of their distribution. Thus will it make us really see those regions 

 which Jules Verne only showed us in imagination." 



" This is not an empty illusion. M. Faye, comparing all the measure- 

 ments, has reached a result well calculated to surprise us. Under the oceans, 

 in the depths, are rocks of very great density; under the continents, on the 

 contrary, are empty spaces." 



" New observations will modify perhaps the details of these conclusions." 



" In any case, our venerated dean has shown us where to search and 

 what the geodesist may teach the geologist, desirous of knowing the interior 

 constitution of the earth, and even the thinker wishing to sepculate upon the 

 past and the origin of this planet." 



From this extract it will be seen that the most eminent French 

 authorities recognize the conclusions first formulated by Pratt over 

 half a century ago. It only remains to consider the application of 

 Pratt's theorem to the Himalayas and the plateau of Tibet. 



If, as Pratt says, " the density of the crust beneath the moun- 

 tains must be less than that below the plains, and still less than that 

 below the ocean bed," it is very difficult to see how this could have 

 come about except by the greater uplift of the mountains, by the 

 injection of more light material beneath, while a less amount of such 

 material has been injected under the plains, and scarcely any has 

 remained under the ocean bed, because it tends to work out by the 

 path of least resistance. This is the only explanation which satisfies 

 the observed phenomena, and conforms to the known fact that the 

 mountains and plateaus are uplifted by the expulsion of matter 

 from beneath the sea, in world-shaking earthquakes. Thus the 



