300 Professor H. M. Pomett — On Geological JI//potItesis. 



^inaccompanied by any detail of the grounds upon which that 

 hypothesis rests — and of the accepted periods of the geological 

 record ; but not a word about the astronomer's theory of the 

 diminishing velocity of the earth's rotation produced by tidal friction, 

 not a word on the important bearing of this theory on the primary 

 geological problem, the age of the earth. 



I choose this example — the time problem — because there are other 

 sciences dependent for the settlement of this problem on the joint 

 labours of geologist, astronomer, and physicist, and my example 

 therefore illustrates the paramount importance of such joint study. 

 " The biologist," said Professor Huxley,^ " knows nothing whatever 

 of the amount of time which may be required for the process of 



evolution A biologist has no means of arriving at any 



conclusion as to the amount of time which may be needed for 

 a certain quantity of organic change. He takes his time from the 

 geologist." 



This interdependence of scientific studies must be fully recogniged 

 by the geologist, both for his own sake and for the sake of others. 

 He cannot afford to ignore any knowledge possessed by any other 

 science if that knowledge has an important bearing on his own 

 pursuits. Always he must be ready to learn from astronomer, 

 physicist, chemist ; and though to the last of these three he has 

 been generally willing to acknowledge his many obligations — 

 obligations likely to be increased in the near future — he has but too 

 often displayed a desire to avoid the physical and astronomical 

 aspects of geological science. If I am told that I am asking too 

 much from the geologist — making him a kind of universal genius 

 like the ideal poet described in Johnson's "Kasselas" — I reply, 

 " Nothing of the sort ; I am merely insisting upon the absolute 

 necessity that any first-rate geological discoverer or teacher shall 

 keep steadily in view the points at which other sciences may 

 increase his light, and never rest satisfied with either his discoveries 

 or his teaching until he has assured himself that he has borrowed 

 whatever light they can at present afford him." 



4. Sir Archibald Geikie ^ reminds us that the various processes 

 of geological changes occurring at the present day "gain enormously 

 in interest for the student of nature when he reflects that in watching 

 the geological operations of the present day he is brought face to 

 face with the same instruments whereby the very framework of the 

 ■continents has been piled up and sculptured into the present out- 

 lines of mountain, valley, and plain." 



Quite so. The hypothesis of the unchanging laws of nature may 

 not only be regarded as the geological postulate, but as the postulate 

 of all science as at present conceived. We are full}'- justified, too, 

 in assuming, e.g., that the facts summarized by what we call the law 

 of gravitation have been as we know them for a vast period of 

 time. But we can lose nothing by candidly admitting the hypo- 

 thetical character of even this great postulate of all science, and 



^ " Science and Hebrew Tradition," pp. 134, 135. 

 2 Class- Book of Geology, p. 299. 



