2 THE AGE OF THE EARTH 



authority of a skilled observer — to the naturalist and to 

 one who follows some other branch of knowledge, but 

 is interested in the progress of a sister science. 



Two such difficulties were alluded to by Lord Salisbury 

 in his interesting Presidential Address to the British 

 Association at Oxford in 1894, when he spoke of 'two 

 of the strongest objections to the Darwinian explanation ' 

 of evolution — viz. the theory of Natural Selection — as 

 appearing 'still to retain all their force'. The first of 

 these objections was the insufficiency of the time during 

 which the earth has been in a habitable state, as cal- 

 culated by Lord Kelvin and Professor Tait, one hundred 

 million years being conceded by the former, but only 

 ten million b)- the latter. Lord Salisbury quite rightly 

 stated that, for the evolution of the organic world as we 

 know it, by the slow process of Natural Selection, at least 

 many hundred million years are required ; whereas, ' if 

 the mathematicians are right, the biologists cannot have 

 what they demand. . . . The jelly-fish would have been 

 dissipated in steam long before he had had a chance of 

 displaying the advantageous variation which was to make 

 him the ancestor of the human race.' 



The second objection was that ' we cannot demonstrate 

 the process of Natural Selection in detail ; we cannot 

 even, with more or less ease, imagine it'. ' In Natural 

 Selection who is to supply the breeder's place ? ' ' There 

 would be nothing but mere chance to secure that the 

 advantageously varied bridegroom at one end of the 

 wood should meet the bride, who b)" a happy contingency 

 had been advantageously varied in the same direction 

 at the same time at the other end of the wood. It would 

 be a mere chance if they ever knew of each other's exis- 

 tence — a still more unlikely chance that they should resist 

 on both sides all temptations to a less advantageous 

 alliance. But unless they did so the new breed would 

 never even begin, let alone the question of its perpetua- 

 tion after it had beeun.' 



Professor Huxle\', in seconding the vote of thanks to 

 the President, said he could imagine that certain parts 

 of the address might raise a very good discussion 



