SHORT PAPER 



PROFESSOR WILLIAM H. HOBBS, of the University of Wisconsin, read a paper on 

 " Suggestions regarding a Petrographic Nomenclature, based on the Quantitative 

 Classification," in which he said: 



" The year 1903 was a remarkable one in the history of petrography. The 

 chaotic condition hi which petrographers have found the system of classification 

 and of nomenclature was nowhere better illustrated than in 1897, at the Interna- 

 tional Congress of Geologists, in St. Petersburg. The largest and most represent- 

 ative body of petrographers ever assembled was there unable to fix upon any 

 principles which could be utilized to improve the situation. 



" With the close of the year 1903, the situation has materially changed, and the 

 credit for this is almost entirely due to the work of five men. Without the work 

 of the pioneer member of the company , Mr. W. F. Hillebrand, of the U. S. Geolog- 

 ical Survey, the results could not have been secured, owing to a lack of adequate 

 data upon which to construct a system. The large series of accurate analyses 

 which were brought together and published in 1900, as Bulletin 168 of the U. S. 

 Geological Survey, constitute the first adequate series of accurate analyses of 

 igneous rocks. In 1903 appeared, after years of preparation, the three works which 

 have so profoundly modified the situation. These are: The Quantitative Classi- 

 fication of Igneous Rocks, by Messrs. Cross, Iddings, Pirsson, and Washington; 

 The Chemical Composition of Igneous Rocks, expressed by means of diagrams, 

 by Mr. Iddings; and The Chemical Analyses of Igneous Rocks, published from 

 1894 to 1900, by Mr. Washington. There have since been published The Su- 

 perior Analyses of Igneous Rocks, from Roth's Tabellen, published from 1869 

 to 1884, by Mr. Washington; and a most noteworthy addition to the list of 

 analyses carried out by the Geological Survey." 



After briefly indicating the work of the syndicate, the speaker criticised it to 

 some extent as failing to meet the demands of science, and stated that this paper 

 was intended more to call forth further discussion than to make a contribution 

 to it. 



