230 PROGRESS OF SCIENCE IN THE CENTURY. 



be true that any vindication of the necessity for an 

 observational basis in science is now an anachronism, 

 we should not forget the early struggles towards this 

 essential virtue. Desmarest's conclusion as to the 

 igneous origin of basalt may seem a small result for 

 years of patience, but we have only to contrast it 

 with the old idea that basaltic columns were petri- 

 fied bamboo stems to see its historical importance. 

 It may not be eas}" to cite any particular conclusion 

 of De Saussure's which is now part of the frame- 

 work of tektonic geology, but his lifework was none 

 the less a vindication of the precept " Go and see." 



l^owadays, no one who is interested in the nature 

 and origin of the sculptured earth around him can 

 " go and see " witliout bearing with him the idea that 

 the earth's crust is a great history-book, that the 

 various layers and strata are pages recording particu- 

 lar processes, and that there has been a '^ geological 

 succession '' still to be deciphered though he who 

 runs may not read it. Yet this familiar and ele- 

 mentary idea of a geological succession had a long 

 history ! 



WeTne7\ — Sir Archibald Geikie refers to Leh- 

 mann, Euclisel, and Werner as three observers who 

 advanced the idea of geological succession during the 

 latter half of the eighteenth century. Of the three, 

 Werner was the most important. He tried to put 

 minerals in order, as Linnscus had done for plants; 

 he was one of the first to expound the general idea of 

 the sequence of geological formations ; and he was an 

 influential teacher of great personal charm. 



Hutton. — In 1785, after years of travel and 

 thought, James Hutton communicated to the Royal 

 Society of Edinburgh the first outlines of his Theory 

 of the Earth, 



