Beinew of Recent Geological Literature. 53- 
MicrosGopiocd Physiography of the Rock-making Minerals: an Aid to the 
microscopisal Study of Mocks. By H. Rosenbusch. Translated and 
abridged for use in Schools and Colleges, by Joseph Iddings. Illustrated 
by 121 woodcuts and 26 plates of photomicrographs. New York, John 
Wiley & Sons, 1888. 
Every well executed effort to introduce to American students and inves- 
tigators the recent views and methods of European, and especially of 
German petrographers, deserves a cordial reception. For such reason, 
we are glad to welcome the translations, complete and partial, which have 
been made of Hussak's Oesteinhildende Mineralien, and of Rosenbusch's 
Classification of Massive Rocks, condensed in a translation by Professor 
Bayley. It would still further aid American petrographic studies if we 
could see in an English dress such other works as Des Cloizeaux' Manuel 
de mineralogie. Von Lasaulx' Einfuhung, Roth's Allgemeine und chemisclie 
Geologie (1879-1887) and Kalkowsky's Elemente der Lithologie. 
Mr. Iddings' translation has been a work of considerable magnitude and 
delicacy. The effort at abridgment has also involved much responsibility. 
Such enterprises embody no temptations to selfishness or ambition. The 
abridgement consists chiefly in the omission of historical and literary 
portions — in part also, of portions explanatory of the diverse views and 
expedients of investigators. It involves the omission of many citations of 
authorities. To a limited extent it consists in the condensation into a 
brief statement, of matter more expanded in the original. The effects of 
these various methods of abridgement are various. Sometimes the omitted 
matter sustains no connection of dependence with matter retained — being 
merely accretionary, and hence separable without violence. Such are the 
" Historical Introduction" and other historical paragraphs, the description 
of the microscopes of Fuess — even his new microscope — and of Voigt and 
Hochgesang, since the action and appliances of the Nachet microscope 
cover about all the ground. Such also are some of the various appliances 
for getting stauroscopic effects, and for accomplishing various other ends. 
Sometimes the omissions are amplifications which in the original shed 
additional light on difficult points. Sometimes also they are intermediate 
steps in a verbal or algebraic argument ; and here the difiiculties of com- 
prehension are evidently increased. Learners need amplification rather 
than ellipses. This is somewhat felt, for example, in the condensation of 
the mathematical discussion of the theory of the behavior of doubly re- 
fracting plates in parallel polarized light. 
As a final result of abridgement we have in this translation 333 pages, 
and 121 cuts in the text. The original contains 664 pages of the same size 
(includidg 88 pages of titles) with 171 cuts in the text. The beautiful 
Newtonian scale of colors is also wanting from the translation. On the con- 
trary, the twenty- six plates of "microgrammes" are reproduced without visi- 
ble deterioration. The abridgement was planned probably, in the interest 
of the American student, "omitting" as the translator says, "what seemed 
to be refinements beyond the needs of the average student." For the 
greater part, this is the result ; but in some cases the omissions increase 
the learner's difiiculties. Simplicity sustains no direct ratio to brevity. 
