AGE OF THE EARTH AS AN ABODE FITTED FOR LIFE. 339 



most probable that the suu has notilluininated the earth for 100,000,000 

 years, and almost certain that he has not done so for 500,000,000 years. 

 As for the future, we may say with equal certainty, that the inhabitants 

 of the earth can not continue to enjoy the light and heat essential to 

 their life for many million years longer, unless new sources, now 

 unknown to us, are prepared in the great storehouse of creation." 



I said that in the sixties and I repeat it now; but with charming 

 logic it is held to be inconsistent with a later statement that the sun has 

 not been shining 60,000,000 years; and that both that and this are 

 stultified by a still closer estimate which says that probably the sun 

 has not been shining for 30,000,000 years ! And so my efforts to find 

 some limit or estimate for geological time have been referred to and put 

 before the public, even in London daily and weekly papers, to show how 

 exceedingly wild are the wanderings of jihysicists, and how mutually 

 contradictory are their conclusions as to the length of time which has 

 actually passed since the early geological epochs to the present date. 



Dr. Haughton further goes on : 



" This result (100 to 500 million years) of Professor Thomson's, although 

 very liberal in the allowance of time, has offended geologists, because, having 

 been accustomed to deal ivith time as an infinite quantity at their disposal, 

 they feel naturally embarrassment and alarm at any attempt of the science 

 of physics to place a limit upon their speculations. It is quite possible 

 that even a hundred million of years may be greatly in excess of the 

 actual time during which the sun's heat has remained constant." 



5. Dr. Haughton admitted so much with a candid open mind 5 but 

 he went on to exjjress his own belief (in 1865) thus : 



''Although I have spoken somewhat disrespectfully of the geological 

 calculus in my lecture, yet I believe that the time during which organic 

 life has existed on the earth is practically infinite, because it can be 

 shown to be so great as to be inconceivable by beings of our limited 

 intelligence." 



Where is inconceivableness in 10,000,000,000"? There is nothing 

 inconceivable in the number of persons in this room, or in London. 

 We get up to millions quickly. Is there anything inconceivable in 

 30,000,000 as the population of England, or in 38,000,000 as the popu- 

 lation of Great Britain and Ireland, or in 352,704,863 as the population 

 of the British Empire? Not at all. It is just as conceivable as half a 

 million years or 500 millions. 



6. The following statement is from Professor Jukes's Students' Man- 

 ual of Geology : 



" The time required for such a slow process to effect such enormous 

 results must of course be taken to be inconceivably great. The word 

 I inconceivably' is not here used in a vague but in a literal sense, to 

 indicate that the lapse of time required for the denudation that has 

 produced the present surfaces of some of the older rocks is vast beyond 

 any idea of time which the human mind is capable of conceiving. 



" Mr. Darwin, in his admirably reasoned book on the origin of species, 

 so full of information and suggestion on all geological subjects, estimates 

 the time required for the denudation of the rocks of the Weald of Kent, 



