those on the external conditions of plant life and the marine biological stations of Europe. The book is well illustrated and contains an appendix upon the work of the laboratory.
Preparatory Physics. By William J. Hopkins. New York: Longmans, Green & Co. Pp. 147.
The author of this laboratory manual is Professor of Physics in the Drexel Institute, Philadelphia, and the course of experiments here presented has grown out of the needs of his classes in beginning their study of the science. The greater part of the experiments relate to mechanics, for the author regards this subject "as being fundamental, particularly susceptible of treatment in this manner, with comparatively simple apparatus; and because the student is very greatly aided in thoroughly comprehending its problems by investigating them experimentally." Besides mensuration, the matters investigated under the bead of mechanics are the composition of forces and of motions, levers and pulleys, breaking strength of a wire, deflection of beams, the inclined plane, the pendulum, etc. The properties of liquids are quite fully illustrated, and the book includes also a few experiments on heat, sound, light, and magnetism. The author maintains that only quantitative work is of value to the beginner in physical experimentation find he prefers to avoid those subjects in which only discouragingly inaccurate results are obtainable with the methods and apparatus that the beginner can use.
Manual of Physico-chemical Measurements. By Wilhelm Ostwald. Translated by James Walker, Professor of Chemistry in University College, Dundee. New York: Macmillan & Co. Pp. 255. Price, $2.25.
Dr. Ostwald has now added to his valuable chemical works one on the border land between chemistry and physics. It deals with microscopic measurements of length, accurate weighing, the use of thermometers, thermostats, and calorimeters, of barometers and manometers, processes for determining volumes and densities, optical and electrical measurements, determinations of solubility, etc. The author confesses to "a special pleasure in 'pottering' and making things for myself," and urges his fellow-workers to adopt the practice of working with homemade apparatus. To facilitate their doing so he includes in this volume directions for making a logarithmic slide-rule, for marking scales on glass, and for soft and hard soldering, giving also a special chapter on glass-blowing. By these means he has "striven to combat that helplessness nowadays so prevalent among experimenters, who have to resort to this mechanic for every trifle." A section on weight-testing and several tables have been reprinted by permission from Kohlrausch's Physical Measurements. The tables in the volume comprise only those that are absolutely essential, the work of Landolt and Börnstein being referred to for all others.
A commendable feature in the System of Physical Culture, prepared expressly for public-school work by Louise Preece (C. W. Bardeen, Syracuse, N. Y.), is that every exercise can be taken by the pupils when standing in the aisles beside their seats. The conditions are prescribed for the exercises that the work should be such as will appeal to the sense of the beautiful, combining strength and freedom of movement; that it must be such as can be done by the pupils in the schoolroom within the usual limitations of space and time; that the movements shall be such as can be conducted in a systematic, orderly manner, without causing confusion; and that they must be such as do not demand a change of dress. The directions are analyzed and arranged by Louise Oilman Kielv, of the University of Minnesota, and illustrated by the author with 180 graceful half-tones and 50 cuts. (Price, $2.)
In his paper on the Status of the Mind Problem, selected from a course of lectures delivered before the Anthropological Society of Washington, Lester F. Ward compares the old metaphysical and the modern scientific methods of mind-study, and argues in favor of the latter. In this method mind is considered as an attribute of the physical structure. If the charge of materialism is applied to this view, the author answers that, using the word materialism in its only proper and legitimate sense as postulating the material nature of the mind itself, "the scientific conception, of mind is the farthest
