188 THE FIGURE OF THE EARTH. [MayiC;03, 



Discussion. 



The President said that the subjects considered by the Author 

 in this paper, though rarely dwelt upon by the geologist, came very 

 naturally within the purview of the science. As he had himself 

 often dealt with some of them, mainly from the point of view of 

 present phenomena and present causes, he would refrain from joining 

 in the discussion. It would be interesting to know, however, why 

 those who inferred an original pear-shaped figure for the earth did 

 not point out that even the present spheroid of revolution is 

 somewhat pear-shaped — the northern or land-hemisphere, w T ith its 

 central Arctic depression, calling to mind the broad end of the pear, 

 the southern oceans the waist, and the Antarctic continent the 

 so-called ' stem.' 



The Author, in reply to questions, said that he feared the most 

 serious objection to his method was that it was empirical rather than 

 speculative. The circular alignment of many important terrestrial 

 features was a fact as definite as the succession of strata in a quarry : 

 that the centres of circular systems lay upon great circles which 

 followed the trend of lines of weakness and movement was equally 

 certain, though no explanation had been offered of this coincidence. 

 The correspondence of the pole of terrestrial symmetry with that of 

 the longest equatorial diameter was a result which followed from 

 observation. The Author had made use of centres of circles rather 

 than tangents, because they required fewer data for their determin- 

 ation ; their employment was new, and likely therefore to arouse 

 distrust, but the unexpected coincidences to which their correlation 

 led should inspire confidence. Whether the method were legitimate 

 or not, the pear-shaped form, now that it was pointed out, became 

 obvious to mere inspection : it was a geographical fact, and not a 

 speculation. The question as to which was the stalked end of the 

 pear was a matter of secondary importance, and the Author had no 

 wish to start a controversy between the ' big-endians ' and the 

 ' little-endians.' There was no uncertainty in his own mind with 

 regard to the present position of the stalk : its centre corresponded 

 to the African pole of the longest equatorial diameter ; but, if 

 mathematicians authoritatively decided that it should lie at the 

 antipodes of this, then it followed that the primitive stalk had 

 disappeared, and the present must have been secondarily produced 

 by a more or less symmetrical breaking-down of the broad end. 

 The President's pear differed from the Author's and from Mr. Jeans's ; 

 its long axis extended diametrically across the Pacific belt of land. 

 Forms of a higher degree of symmetry than that described did 

 not seem to exist ; the tetrahedron of Lowthian Green was not the 

 same as that of Michel-Levy, nor the latter as that of Marcel 

 Bertrand ; these ideal forms were as discordant one with the 

 other as they were with the facts. 



