May 12, 1899.] 



SCIENCE. 



667 



unknown to ns, 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 

 he inconsistent with a later statement that 

 the sun has not been shining 60,000,000 

 j-ears, 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 exceed- 

 ingly wild are the wanderings of physicists, 

 and how mutually contradictory are their 

 conclusions, as to the length of time which 

 has actually passed since the early geo- 

 graphical epochs to the present date. 



Dr. Haughton further goes on : 



" This result (100 to 500 million years) of Profes- 

 sor Thomson's, aWiough very liberal in the allowance of 

 time, has offended geologists, iecause, having been accus- 

 tomed to deal with 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 

 tJieir 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 re- 

 mained constant." 



§ 5. Dr. Haughton admitted so much 

 with a candid open mind, but he went on 

 to express his own belief (in 1865) thus : 



"Although I have spoken somewhat disrespect- 

 fully of the geological calcuhis 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 population of Great Britain 

 and Ireland, or in 352,704,863 as the popu- 

 lation 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' Manual 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 ' inconceivably ' 

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

 indicate that the lapse of time required for the de- 

 nudation that has produced the present surfaces of 

 some of the older rooks 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 sug- 

 gestion on all geological subjects, estimates the time 

 required for denudation of the rocks of the Weald of 

 Kent, or the erosion of space between the ranges of 

 chalk bills, known as the North and South Downs, at 

 three hundred millions of years. The grounds for form- 

 ing this estimate are, of course, of the vaguest de- 

 scription. It may be possible, perhaps, that the 

 estimate is a hundred times too great, and that the 

 real time elapsed did not exceed three million years, 

 but, on the other hand, it is just as likely that the 

 time which actually elapsed since the first commence- 

 ment of the erosion till it was nearly as complete as 

 it now is was really a hundred times greater than his 

 estimate, or thirty thousand millions of years." 



§ 7. Thus Jukes allowed estimates of 

 anything from 3 millions to 30,000 millions 

 as the time which actually passed during 

 the denudation of the Weal d . On the other 

 hand. Professor Phillips, in his Rede lecture 

 to the University of Cambridge (1860), de- 

 cidedly prefers one inch per annum to Dar- 

 win's one inch per century as the rate of 

 erosion, and says that most observers 

 would consider even the one inch per an- 

 num too small for all but the most invin- 

 cible coasts ! He thus, on purely geological 

 grounds, reduces Darwin's estimate of the 

 time to less than one one-hundredth. And, 

 reckoning the actual thicknesses of all the 

 known geological strata of the earth, he 

 finds 96 million years as a possible estimate 

 for the antiquity of the base of the stratified 

 rocks ; but he gives reasons for supposing 

 that this may be an overestimate, and he 



