Mr. _W. W. Campbell's Elements of Practical Astronomy_[15] is an evolution. It grew out of the lessons of his experience in teaching rather large classes in astronomy in the University of Michigan, by which he was led to the conclusion that the extensive treatises on the subject could not be used satisfactorily except in special cases. Brief lecture notes were employed in preference. These were written out and printed for use in the author's classes. The first edition of the book made from them was used in several colleges and universities having astronomical departments of high character. The work now appears, slightly enlarged, in a second edition. In the present greatly extended field of practical astronomy numerous special problems arise, which require prolonged efforts on the part of professional astronomers. While for the discussion of the methods employed in solving such problems the reader is referred to special treatises and journals, these methods are all developed from the _elements_ of astronomy and the related sciences, of which it is intended that this book shall contain the elements of practical astronomy, with numerous references to the problems first requiring solution. The author believes that the methods of observing employed are illustrations of the best modern practice. [15] The Elements of Practical Astronomy. By W. W. Campbell. Second edition, revised and enlarged. New York: The Macmillan Company. Pp. 264. Price, $2. In _The Characters of Crystals_[16] Prof. _Alfred J. Moses_ has attempted 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 discussions. The first part of the book relates to the geometrical characteristics of crystals, or the relations and determination of their forms, including the spherical projection, the thirty-two classes of forms, the measurement of crystal angles, and crystal projection or drawing. The optical characters and their determination are the subject of the second part. In the third part the thermal, magnetic, and electrical characters and the characters dependent upon electricity (elastic and permanent deformations) are treated of. A suggested outline of a course in physical crystallography is added, which includes preliminary experiments with the systematic examination of the crystals of any substance, and corresponds with the graduate course in physical crystallography given in Columbia University. The book is intended to be useful to organic chemists, geologists, mineralogists, and others interested in the study of crystals. The treatment is necessarily technical. [16] The Characters of Crystals. An Introduction to Physical Crystallography. By Alfred J. Moses. New York: D. Van Nostrand Company. Pp. 211. Price, $2.