204 WHAT IS LIFE ? 



then the same part became a temperate or a far warmer 

 climate. 1 No doubt these alterations were very, very 



1 " That the axis of the Earth's rotation has successively shifted, 

 and consequently that the poles have wandered to different points on 

 the surface of the globe, has been maintained by geologists as the 

 only possible explanation of certain remarkable conditions of climate, 

 which can be proved to have formerly obtained within the Arctic 

 Circle. Even as far north as lat. 81 45', abundant remains of a 

 vegetation indicative of a warm climate, and including a bed of coal 

 25 to 30 feet, have been found in situ. It is contended that when 

 these plants lived, the ground could not have been permanently 

 frozen or covered for most of the year with thick snow. In ex- 

 planation of the difficulty, it has been suggested that the north pole 

 did not occupy its present position, and that the locality where the 

 plants occur lay in more southerly latitudes. . . . we can, without 

 having recourse to any extra-mundane influence, recognise two causes 

 which, whether or not they may suffice to produce any change in the 

 position of the main axis of inertia, undoubtedly tend to do so. In 

 the first place, a widespread upheaval or depression of certain un- 

 symmetrically arranged portions of the surface to a considerable 

 amount would tend to shift that axis. In the second place, an 

 analogous result might arise from the denudation of continental 

 masses of land, and the consequent filling up of sea-basins." 

 ("Text-Book of Geology," Sir Archibald Geikie, F.R.S., 1893, 

 p. 17.) 



" We are . . . most interested by the labours of Mr. Chandler, 

 a distinguished American astronomer, who has made an exhaustive 

 examination into the subject. The result has been to prove that the 

 Pole does undergo movement in the body of the earth. Mr. Chandler 

 has been so successful as to have determined the law of those polar 

 movements, and he has found that when they are taken into con- 

 sideration an important improvement in certain delicate astronomical 

 inquiries is the result. These valuable investigations merit, in the 

 highest degree, the attention, not only of those who are specially de- 

 voted to astronomical and mathematical researches, but of that large 

 and ever-increasing class who are anxious for general knowledge with 

 regard to the physical phenomena of our globe." (" In the High 

 Heavens," Sir R. S. Ball, D.Sc., LL.D., F.R.S., 1894, p. G7.) 



