SYSTEMATIC PETROGRAPHY 371 
advance was made in the systematic classification of rocks in 
that country. And when a very significant advance was made, 
it appears not to have been recognized. The master spirit of 
French petrography during this period and until his death was 
Raw. Cordier, Ee was engaged until the end in carefully 
elaborating his system of classification, which was presented 
in lectures and applied to the great collection of the Museum 
of Natural History in Paris. Cordier does not seem to have 
published his classification himself, but it was made known 
by his associate, Charles d’Orbigny, in the Dictionnaire universel 
a@ histoire naturelle, article ‘‘ Roches,” and others, Paris, 1842-1848; 
and in the volume Description des roches, etc., edited from the 
manuscript and lectures of Cordier, published in Paris, 1868, 
seven years after his death.’ 
The stagnation in systematic petrography in France during 
this period may be referred to two causes: First, the inherent 
weakness of Cordier’s system; and, second, the traditional 
custom prevailing in France which gives to the recognized 
master in any branch of science a strongly dominant influence, 
which few. are willing to openly oppose. 
The weakness of. Cordier’s system came chiefly from the fact 
that it was, like that of Hatiy, based too largely upon the con- 
venient arrangement of cabinet specimens. Viewing rocks 
simply as aggregates of minerals, they were studied in detail, and 
their broad relationships were ignored, as belonging wholly to 
geology. In 1848, only two years before Naumann issued his 
philosophical analysis of petrography, and 33 years after Cordier 
published his own first scheme for the arrangement of volcanic 
rocks, his comprehensive system was announced by D’Orbigny, 
in the cited article of the Dictionnaire universel, etc., to have the 
following features : 
Its fundamental idea was that the classification of rocks 
should be grouping of sfeczes, not a subdivision of the grand 
category of rocks. The species, based upon composition, was 
TAt an earlier date it was translated into German by Kleinschrod, in /akrouch 
fiir Mineralogie, 1831, p. 17. 
