gi2 THE AMERICAN NATURALIST. 
PETROGRAPHY AND MINERALOGY. 
The Characters of Crystals.1— “I have attempted, in this book, 
to describe, simply and concisely, the methods and apparatus used 
in studying the physical characters of crystals, and to record and 
explain the observed phenomena without complex mathematical dis- 
cussions” (from author’s preface). 
The book is divided into three parts and fourteen chapters. The 
first part discusses the geometrical characters of crystals, the second 
part the optical characters, and the third part the thermal, magnetic, 
and electrical characters and those depending upon elasticity and 
cohesion. In an appendix of seven pages a laboratory course in 
physical mineralogy is outlined. 
While there is nothing new in the presentation or in the subject- 
matter of the little volume, it nevertheless will be useful as a labora- 
tory manual, since there are to be found in it very concise descriptions 
of all the methods usually made use of in determining the physical 
constants of crystals, and in recording the results of angle measure- 
ments. In order, however, that it may be of the greatest value to 
the student, the topics discussed in it should be preceded by a course 
of lectures in which the principles involved in the descriptions are 
explained in more detail than has been done in the book. 
Many of the methods described are here presented for the first time 
in English, and for this reason, if for no other, the little volume should 
meet with a welcome in all mineralogical laboratories. W., S. B. 
The First Appendix to the Sixth Edition of Dana’s System of 
Mineralogy, by Edward S. Dana,’ completes this great work to the 
beginning of the year 1899. It includes a list of the new mineral 
names that have been proposed since the System of Mineralogy 
appeared, descriptions of each of the substances indicated by these 
names, and an account of all the important additions to our knowl- 
edge of the species described in the large manual. A vast amount 
of information is included in the seventy-five pages of the Appendix, 
and all of it may be depended upon as being trustworthy. 
The System, with the addition of the Appendix, probably consti- 
tutes the most complete summary of a science that exists in any 
language. W. S. B. 
1 Moses, Alfred J. Zhe Characters of Crystals. An Introduction to Physical 
Crystallography. New York, D. Van Nostrand Company, 1899. viii + 211 pp. 
321 figs. 
2 New York, John Wiley & Sons, 1899. x+75 pp. Price, $1.00. 
