OE THE EAETB^S AXIS OE FIGVEE. 47 



The whole circuit of the northern regions was being rapidly ex- 

 plored, and everywhere the temperate forms of life were found 

 dying out towards the present Pole in ancient time as now ; whereas 

 if the Pole had shifted we ought to find evidence of what became 

 the polar regions when the ancient plant-bearing Arctic regions had 

 been drawn down into more temperate zones. 



Prof. Ramsay referred to the former prevalence in geology of 

 views which had long since been exploded, and expressed his opinion 

 that before long the theory of the fixed geographical position of the 

 poles of the earth would share the same fate. The flora of various 

 deposits in Polar lands indicated the growth of plants which would 

 require the stimulus of light, even if the necessary amount of heat 

 for their growth could be accounted for. With respect to great 

 local changes of level, he remarked that the northern part of Africa 

 was below the level of the sea in very recent times ; and there was 

 reason to suppose that even later than the Miocene epoch a vast 

 tract of land occupied the space between what were now the 

 continents of Africa and Asia. Of course no one supposed that the 

 position of the poles had been changed by rapid upheavals of land ; 

 but as we know that all geological changes of level have been slow 

 and gradual, so the poles may have altered their position by a 

 process as slow as that evolution which has originated the species 

 of animals and plants during the long series of geological time. 

 Such questions as these were serious, involving the results of much 

 observation on the ground, and could not, he thought, be solved in 

 the closet by any amount of abstract work alone. 



Mr. A. W. Watees called attention to the large amount of matter 

 removed from one position to distant positions ; for the amount of 

 solid matter carried down by rivers in solution is enormous, some- 

 thing like 5,000,000,000 tons being annually removed from the 

 land surface, which is equal to the weight of Vesuvius removed in 

 ten years. This gives a gain to the southern hemisphere of about 

 3,500,000,000 tons per annum, or one Vesuvius in fourteen years ; 

 but from Mr. Twisden's figures, the weight of Europe would have 

 to be removed 166 times to give a change of 20 degrees. The cal- 

 culations of the author are all based upon the earth being perfectly 

 rigid ; but this geologists cannot admit, considering the movements 

 of the crust in continental and mountain elevation ; and Sir William 

 Thomson said in his Address at Glasgow, that if the earth were as 

 solid as steel it would still take the same equatorial bulge. The 

 geographical position of the axis might then be changed, and yet 

 the axis always hold the same position with regard to heavenly 

 bodies. 



Rev. J. E. Blake remarked that mathematics can only give true 

 results if they have true observations to work upon. The results in 

 the present case came out much smaller than non-mathematicians 

 would suppose. He questioned whether so great an amount of 

 divergence as was sometimes assumed was possible, but at the same 

 time the effects of change of figure would be cumulative. Eleva- 

 tions and depressions consequent upon something going on in the 



