358 WHITMAN CROSS 
texture, and other properties are occasionally used for minor 
unnamed divisions. After the elaborate preparation for this 
arrangement, it must be confessed that Naumann failed utterly 
to produce a system worthy of the name. No logical and con- 
sequent application of principles can be found in his Synopsis. 
The great value of Naumann’s work lies in the clear setting 
forth of the scope of the general science of rocks, independently 
of their formal or historical relations to the earth. He outlined 
the divisions under the broad science, and showed the proper 
position of the purely systematic and descriptive branch. He 
illustrated clearly how many arrangements or groupings of rocks 
are natural and necessary from the geologist’s standpoint, and 
evidently understood that he could not introduce all these con- 
siderations into the construction of one system of classification. 
In the development of petrographical system, Naumann’s 
analysis of the broad science was of great importance. For 
many years the primary classification of rocks, leading to an 
arrangement for purposes of description, followed some of the 
various ways set forth by him. And even at the present day we 
find H. Credner, a successor of Naumann in the university at 
Leipzig, presenting rock descriptions in his well-known Elemente 
der Geologie under a framework very similar to that of the Lehr- 
buch der Geognoste. Whatever the choice of criteria adopted by 
individuals from among the alternatives presented by Naumann, 
very similar, if not identical, major divisions were formed. 
Bernhard von Cotta, 1555, 1562.—Almost contemporaneovsly 
with Naumann’s Geognosie appeared several other treatises on 
rocks by German authors of note. De Gesteinslehre, by Bern- 
hard von Cotta, was first published in 1855, and its second edi- 
tion in 1862, the latter being translated into English and serving 
for years as a standard work. 
The first edition of the Gesteznslehre professes to be merely a 
description of rocks, and the arrangement or order in which the 
various kinds are presented is stated to be one of convenience 
only. Von Cotta’s point of view was that, as rocks are simply 
aggregates of mineral particles, one kind grading into another, 
