with philosophical accuracy, only in its connection with iron and steel, and in the influence excited by the earth as a whole, the accurate portions of this work are confined to the investigations connected with these metals and the earth. The latter part of the work, however, treats in a more general way of the laws of the connection between Magnetism on the one hand and Galvanism and Thermo-Electricity on the other. The work is divided into Twelve Sections, and each section into numbered articles, each of which states concisely and clearly the subject of the following paragraphs.
Ball (R. S., A.M.)— EXPERIMENTAL MECHANICS. A Course of Lectures delivered at the Royal College of Science for Ireland. By Robert Stawell Ball, A.M., Professor of Applied Mathematics and Mechanics in the Royal College of Science for Ireland (Science and Art Department). Royal 8vo. 16s.
The author's aim in these twenty Lectures has been to create in the mind of the student physical ideas corresponding to theoretical laws, and thus to produce a work which may be regarded either as a supplement or an introduction to manuals of theoretic mechanics. To realize this design, the copious use of experimental illustrations was necessary. The apparatus used in the Lectures and figured in the volume has been principally built up from Professor Willis's most admirable system. In the selection of the subjects, the question of practical utility has in many cases been regarded as the one of paramount importance, and it is believed that the mode of treatment which is adopted is more or less original. This is especially the case in the Lectures relating to friction, to the mechanical powers, to the strength of timber and structures, to the laws of motion, and to the pendulum. The illustrations, drawn from the apparatus, are nearly all original and are beautifully executed. "In our reading we have not met with any book of the sort in English."—Mechanics' Magazine.
Bayma.—THE ELEMENTS OF MOLECULAR MECHANICS. By Joseph Bayma, S.J., Professor of Philosophy Stonyhurst College. Demy 8vo. cloth. 10s. 6d.
Of the twelve Books into which this treatise is divided, the first and second give the demonstration of the principles which bear directly on the constitution and the properties of matter. The next
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