158 A CENTUEY OF SCIENCE 



of structures connected with mountain making, and 

 emphasis will be placed upon the growth of understand- 

 ing rather than upon the accumulating knowledge of 

 details. The growth in both of these divisions of struc- 

 tural geology is well illustrated in the volumes of the 

 Journal. 



Structures and Relationships of Igneous Rocks. 

 Opposed Interpretations of Plutonists and Neptunists. 



During the first quarter of the nineteenth century the 

 geologic controversy between the Plutonists and Nep- 

 tunists was at its height; the Plutonists, following the 

 Scotchman, Button, holding to the igneous origin of 

 basalt and granite, the Neptunists, after their German 

 master, Werner of Freiberg, maintaining that these 

 rocks had been precipitated from a primitive universal 

 ocean. The Plutonists, although time has shown them to 

 have been correct in all essential particulars, were for a 

 generation submerged under the propaganda carried for- 

 ward by the disciples of Werner. The " Illustrations of 

 the Huttonian Theory of the Earth," a remarkable clas- 

 sic, worthy of being studied to-day as well as a century 

 ago, was published in 1802 by John Playfair, professor of 

 mathematics in the University of Edinburgh and a friend 

 of Hutton, who had died five years previously. This 

 volume was opposed by Robert Jameson, professor of nat- 

 ural philosophy in the same university, who had absorbed 

 the ideas of the German school while at Freiberg 

 and published in 1808 a volume on the "Elements of 

 Geognosy," in which the philosophy of Werner is fol- 

 lowed throughout and even obsidian and pumice are 

 argued to be aqueous precipitates. The authority of the 

 Wernerian autocracy caused its nomenclature to be 

 adopted in the new world, but strong evidence against 

 its interpretations was to be found in the actual struc- 

 tural relations displayed by the igneous rocks. 



Contributions on Volcanic and Intrusive Rocks. 



The accumulation and study of facts constituted the 

 best cure for an erroneous theory. The publications of 

 the Journal contributed toward this end by articles along 



