228 Davis — Framework of the Earth. 



geology at the end of the eighteenth and the opening 

 of the nineteenth centuries; but these and other early 

 works were necessarily based npon imperfect knowledge 

 of restricted fields, the observational study of which had 

 not been standardized. Some of their generalizations 

 were inevitably incorrect ; yet the old masters were wise 

 in many of their speculations, and their writings are still 

 profitable reading, if only to learn how great a present- 

 day science has been built up from the foundations that 

 they and their contemporaries laid down a century ago. 



Lyell provided in his "Principles of Geology' ' a 

 broader establishment, through the middle of the nine- 

 teenth century, for many of the generalizations that his 

 predecessors had formed. His great contribution to earth 

 science was the fuller demonstration that gratuitous over- 

 drafts made out by geological speculators on the Bank 

 of Terrestrial' Forces must be returned, marked "No 

 Funds.' ' Yet that able and fair-minded uniformitarian 

 nowhere gave adequate treatment to the great problem 

 of mountain-making ; and he was so little constrained by 

 the historical geology of the continents, as known in his 

 time, that he felt free to suggest a fundamental rear- 

 rangement of land and water at so late a date as the 

 Pleistocene, in order to account for the climatic changes 

 which the Glacial period demands. Even when the latest 

 of his own revisions of the "Principles" appeared, geo- 

 logical exploration was so little advanced that no general 

 summary of earth structure was legitimately possible. 



Still less possible was it some fifteen years earlier, 

 when Elie de Beaumont announced his venturesome 

 scheme regarding a geometrical arrangement, a "pen- 

 tagonal network," of violently upheaved mountain 

 ranges. It is interesting to recall that this scheme was 

 set forth in an essay originally intended to give a sum- 

 mary of the science of geology in d'Orbigny's "Dic- 

 tionnaire universelle d'histoire naturelle"; but as the 

 dictionary was too far advanced for the essay to appear 

 under G, it was named "Montagnes," and thus post- 

 poned to M, so that the busy author might have more 

 time for its preparation. When M was approached, the 

 essay, still belated, was renamed "Soulevements et 

 Revolutions du Globe"; and when "Soulevements" was 

 reached the essay was again deferred to "Systemes de 

 Montagnes." In the meantime the manuscript had far 



