JE I TORIAL 
THE meeting of the Committee on Rock Nomenclature, 
appointed by the International Geological Congress, which was 
held in Paris last October, failed to elicit concerted action on 
the part of petrographers. Only two reports were received from 
committees representing different countries. They were from 
Russia and France, and will be transmitted to the Congress. 
The small attendance at the meeting, the wide divergence of 
views indicated by members expressing themselves by letter, and 
the desire of independence manifested by all, make it impossi- 
ble for the committee as a whole to transmit a report to the con- 
gress. Each petrographer is expected to present his views in 
his own way at the coming meeting in Paris. 
Apparently there has been no progress toward harmony of 
nomenclature or of rock classification. Phere is still a wide 
divergence of ideas concerning rocks themselves and the methods 
of dealing with them. While this is to be regretted, it is not to 
be wondered at, considering the abstract petrological, as well as 
the anthropic, elements involved in the problem. However, 
there are indications of advancement along more or less con- 
verging lines that will eventually unite. In the meantime every 
petrographer is a law unto himself, as is evident from articles 
recently published in this JouRNAL and elsewhere. 
PROFESSOR Hosss, in his discussion of this subject in this 
volume of the JourNAL, has laid special emphasis on the value of 
diagrams in conveying ideas of relative quantities of chemical 
constituents of rocks, availing himself of Brégger’s modification 
of Michel-Lévy’s diagrams. The importance of such devices 
for expressing relative quantities and for permitting ready com- 
parison of many variable factors in an intricate problem cannot 
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