STABILITY OF A GRAVITATING PLANET. 
183 
consideration of the actual figure of the earth, and it is that which might naturally 
he expected. The theory put forward in this paper may, perhaps, suggest a reason 
why these regions should lie approximately on a great circle of the earth, and why 
this great circle should approximately divide the earth into two hemispheres of sea 
and land. 
Summary and Conclusion. 
§ 39. In conclusion it may he well to summarise those parts of the ])aper which 
refer to the hgure of the earth. 
We saw that at the moment of solidification the earth might he either spherical 
(except in so far as it was deformed l)y its rotation) or pear-shaped. Our theoretical 
calculations and our knowledge of the constants of the earth at the time of solidi¬ 
fication were not sufficientlv accurate to enahle us to decide wlucli of the two 
alternatives is the iiun-e pro})ahle. Tlie sliape of the eartli, whether spherical or pear- 
shaped, could not he maintained long against tlie enormous strains wliicli would be 
set up in the earth as the pr(.)cess of cooling |n-oceeded, and this sliape would gradually 
give place to an approximately splierlcal shape, the change in shape being produced 
by a long succession of ruptures. Tl^e suggestion of tliis jiaper is that the eartli, in 
spite of this series of ruptures, still shows traces of a, pear-shaped conhguration. 
Such a conhguration would possess a single axis of symmetry, and this, it is suggested, 
is an axis which meets tlie earth’s surface someAvliere in the neighbourhood of 
England (or, possibly, some hundreds of miles to the S.W. of England). Starting 
from England we have in the hrst place a hemisphere wliicli is practically all land ; 
this would he the blunt end of our jiear. Bounding this 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 freciuent occunence. If we suppose our pear contracting to a 
spherical shape we notice that it would prolialily he in the neighliouihood of its 
equator that the change in curvature and the relative displacements would he 
greatest, and lienee we should expect to find earthquakes and volcanoes in greatest 
numliers near to tliis circle. Passing still furtlier from England we come to a great 
region of deep seas—the Pacific Ocean, tlie South Atlantic Ocean, and the Indian 
Ocean : these may mark the place where tlie “waist” of the pear occurred. Lastly 
we come, almost at the antipodes of England, to the Australian continent and tlie 
shallow seas wiiich lie to the east of it; these may he the remains of tlie stalk-end of 
the jiear. 
§ 40. It may, I am afraid, he thought that the hypotheses upon whicli the paper is 
based are too speculative and the results, consequently, too uncertain. In defence it 
may be said that the object of the paper is not so much to establish new doctrines as 
to point out possibilities, and that these possibilities seem to be of such a kind tliat it 
may be useful to keep them in mind in discussing questions connected with the figure 
