1908.] 



THE PHYSICS OF THE EARTH. 275 



England we find that England is at the centre of a hemisphere which is 

 practically all land; this would be the blunt end of our pear. Bounding 

 the hemisphere we have a great circle, of which England is the pole, and it 

 is over this circle that earthquakes and volcanoes are of most frequent 

 occurrence. Now, if we suppose our pear contracting to a spherical shape, 

 we notice that it would probably be in the neighbourhood of its equator 

 that the changes in curvature and the relative displacements would be 

 greatest, and hence we would expect to find earthquakes and volcanoes in 

 greatest number near this circle. Passing still further from England, we 

 come to a great region of deep seas, the Pacific, South Atlantic, and Indian 

 Oceans ; these may mark the place where the ' waist ' of the pear occurred. 

 Lastly we come almost to the antipodes of England, to the Australian conti- 

 nent. This may mark the remains of the stalk-end of the pear." {Nature, 

 Vol. LXVIL, p. 190.) 



After what has been shown in this series of papers, it is un- 

 necessary to dwell upon this hypothesis of Professor Jeans, which 

 has the merit of originality; but we may remark that if it gave a 

 true view of the physics of the earth, there should be a belt 

 around the globe of at least the width of the terrestrial radius, over 

 which the earthquakes are about equally distributed, whereas in 

 fact they are felt principally along the margins of the Pacific 

 Ocean. The observed earthquake belt on land is so narrow that 

 it is clearly impossible to ascribe the effects to this supposed adjust- 

 ment of the earth's figure. And of course it fails totally to ac- 

 count for the sinking of the sea bottom and the uplift of the coast, 

 which is typical of mountain formation. 



