DISSENTIENT PHYSICISTS 213 



400, and 500 million years. I have shown that we 

 have reasons for believing that the age, from all 

 these, may be very considerably underestimated. It 

 is to be observed that if we exclude everything 

 but the arguments from mere physics, the probable 

 age of life on the earth is much less than any of 

 the above estimates ; but if the palaeontologists have 

 good reasons for demanding much greater times, 

 I see nothing from the physicist's point of view 

 which denies them four times the greatest of these 

 estimates.* 1 



This remarkable admission from a recognised 

 authority on the physical side re-echoes and empha- 

 sises the warning pronounced by Professor Darwin 

 in the address already quoted c at present our 

 knowledge of a definite limit to geological time has 

 so little precision that we should do wrong to sum- 

 marily reject any theories which appear to demand 

 longer periods of time than those which now appear 

 allowable.' 2 



This c wrong,' which Professor Darwin so seriously 

 deprecated, has been committed not once, but again 

 and again, in the history of this discussion. Lord 

 Kelvin has never taken any notice of the strong 

 body of evidence adduced by geologists and palaeon- 

 tologists in favour of a much longer antiquity than 

 he is now disposed to allow for the age of the earth. 

 His own three physical arguments have been succes- 

 sively re-stated, with such corrections and modifica- 

 tions as he has found to be necessary, and no doubt 



1 Nature, vol. li. p. 585, April 18, 1895. 

 . Brit. Assoc., 1886, p. 518. 



