*LITERARY NOTICES.*

Twin manuals on *Heat* and *Light* have been prepared for the Cambridge Natural Science Series (Macmillan & Co., New York, $1 each), by *R. T Glazebrook* as elementary text-books, theoretical and practical, for the purpose of serving as aids in teaching by experiments that may be performed by the pupils themselves. Most of the experiments described have been in use for some time as a practical course for students in the Cavendish Laboratory. The rest of the two books contain explanations of the theory of the experiments and accounts of the deductions from them, which have formed the substance of the author's lectures to his class.

The general purpose sought by *Henry Wood* in preparing the *Political Economy of Natural Law* (Lee & Shepard, Boston, $1.25) was to outline a political economy which is natural and practical rather than artificial and theoretical. While independent of professional methods, it aims to be usefully suggestive to the popular mind. The present volume, though substantially a new work, may be regarded as a development from a small book entitled Natural Law in the Business World, published in 1887. A portion of the original matter in that book has been retained, somewhat changed in form. No attempt is made to make people content with things as they are, but to turn the search for improvement in a promising direction. We are glad to see that the author sets himself squarely in opposition to the fallacy that the interest of labor is naturally antagonistic to other social elements, which he thinks justly has done much harm.

After the Congress of Mathematics, held in Chicago, in August, 1893, a *colloquium* on Mathematics was held by Prof. *Felix Klein,* of the University of GĂ¶ttingen, with such other members of the congress as chose to participate, at the Northwestern University, Evanston. During these colloquia Prof. Klein delivered daily lectures, the substance of which was taken down and prepared for publication by Alexander Ziwet. These lectures are now published as a single volume of *Lectures on Mathematics* by Macmillan & Co., New York ($1.50). Three of these lectures relate to the work of the mathematicians Clebsch and Sophus Lie; the others are on The Real Shape of Algebraic Curves and Surfaces, Theory of Functions and Geometry, The Mathematical Character of Space Intuition and the Relation of Pure Mathematics to the Natural Sciences, The Transcendency of the Numbers e and ir, Ideal Numbers, The Solution of Higher Algebraic Equations, Some Recent Advances in Hyperelliptic and Abelian Functions, The Most Recent Researches in Non-Euclidean Geometry, The Study of Mathematics at GĂ¶ttingen, and The Development of Mathematics at the German Universities.

Mr. *Charles H. Clark* has prepared his book on *Practical Methods in Microscopy* (D. C. Heath & Co., Boston, $1.60) in view of his observation that in most of the excellent current books on the microscope too much is assumed to be known by the pupil, or is left to be filled in by an instructor. None of them, he says, gives to the private worker in simple and concise language detailed directions for the many processes that he must learn in order to make practical use of the microscope. The present book is the outgrowth of the author's experience in the use of the instrument in the branches of scientific study pursued in the secondary schools. So much of the mechanical construction of the microscope is given as seems absolutely essential to an intelligent understanding of the instrument. The theory of polarized light has been somewhat fully considered.

The peculiar features of the *Practical Business Bookkeeping by Double Entry* (D. C. Heath & Co., Boston, $1.55), as set forth by the author, *Manson Seavy,* are classification of the subjects treated into parts, each forming by itself an independent whole, with subdivisions; full and systematic treatment, with illustrations of recounts; omission of discussion of theory; the acceptance of the forms universally adopted by the best business men and accountants in the treatment of business transactions; full discussion of bills receivable and bills payable; and the original, simple, and intelligible rules given for closing a ledger, which have stood the test of many years with classes of young students. The work is supplemented by another. The Manual of Business Transactions, which contains transactions only, in the describing of which the student must exercise his own judgment, and thus acquire proficiency in the application of principles.