220 Proceedings of the Royal Physical Society. 



Looking back to the two closing decades of last century, 

 we find Geology in the full vigour of its spring-time at Edin- 

 burgh. In the year 1785, Hutton, after many years of patient 

 but enthusiastic research, at last communicated his " Theory 

 of the Earth " to the Eoyal Society of Edinburgh.^ The 

 publication of this great memoir, and of its enlargement ten 

 years afterwards into two octavo volumes,*!' niarked one of the 

 most notable epochs in the progress of science. Geological 

 dynamics were now treated with the bold, broad, far-reaching 

 hand of a consummate master. Men were taught that instead 

 of indulging in the construction of fanciful systems of cos- 

 mogony, it was their first duty to study the actual records of 

 the earth's history which have been preserved among the 

 rocks. They were told that the interpretation of these 

 records was supplied by familiar and daily operations upon 

 the earth's surface ; that the existing economy of nature was 

 alone to be employed in the investigation of past time, and 

 that no imaginary causes of change were to be invoked 

 merely because those now in progress seemed on a cursory 

 view inadequate to explain the vicissitudes through which the 

 planet had passed. One prominent feature in the Huttonian 

 theory was the recognition of a vast cycle of revolutions, of 

 which the evidence could be traced in the rocks of the 

 earth's surface. Hutton found everywhere proofs of continual 

 disintegration. The soil under his feet was in his eyes a 

 monument of the decay of the terrestrial surface, alike neces- 

 sary for the well-being of plants and animals and for the for- 

 mation of land hereafter to be upraised from the bed of the 

 sea. In the strata composing most of the dry land he saw 

 the ruins of a former world — debris that had been worn from 

 earlier continents, and had been laid down upon the fioor of 

 the sea. In the heated interior of the globe he recognised a 



* Theory of the Earth ; or an Investigation of the Laws observable in the 

 Composition, Dissolution, and Restoration of Land upon the Globe, by James 

 Hutton, M.D. ; Trans. Roy. Soc, Edin., i., pp. 209-304, read March 7 and 

 April 4, 1783. 



+ Theory of the Earth, with proofs and illustrations, in 4 parts, 2 vols. 

 8vo, Edinburgh, 1795. [A third volume in MS. is referred to by Playfair 

 {Trans. Roy. Soc. Edin., v., part iii., p. 86) as having been left by the author, 

 but it was never published, and no trace of its existence can now be found.] 



