GROWTH OF GEOLOGY. 241 



just as markedly as in connection with the big ques- 

 tion of the history of the Earth as a whole. 



AGE OF THE EAKTH. 



In the early days of geological science, the preva- 

 lent opinion seems to have been that the earth was 

 about 6,000 years old. But this belief was for the 

 most part an outcome of " wresting the Scriptures " 

 from their proper use, and is quite irrelevant in 

 scientific discussion. 



The Age of the Earth as Realised ~by Uniformi- 

 tarians. When James Hutton (1726-1797) began 

 to show that the present supplies the key to the inter- 

 pretation of the past, and saw " the ruins of an older 

 world in the present structure of the globe," it be- 

 came plain to inquiring minds that the earth must 

 be old beyond all telling. 



William Smith's revelation of the succession of 

 strata in England the vision of age before age 

 stretching back into an inconceivably distant past ; 

 the founding of palaeontology by Cuvier and others, 

 and the suggestion of successive faunas and floras 

 leading us back and back to the mist of life's begin- 

 nings; the publication of John Playfair's Illustra- 

 tio?is of the Huttonian Theory (1802); and other 

 great events led to an accentuation of the idea of an- 

 tiquity. Indeed, Playf air went so far as to deny that 

 either earth or cosmos furnished tangible hint of any 

 beginning at all. Thus the earth, which had not 

 long before been credited with a short duration of 

 6,000 years, was at the beginning of the century con- 

 ceived of as a sort of inanimate Methuselah, " with- 

 out beginning of days or end of years." 



Recognitions of Limits. A reaction began in 1862, 

 when Lord Kelvin (then Sir William Thomson) sent 



