Those of our readers who have not a complete file of this magazine, should order at an early date as the snpply of back numbers of volumes I and II is being rapidly exhausted. The present supply is all that can be obtained of these volumes, as the heavy expense of reprinting does not permit of having it done for a whole volume.

When making inquiries through the Correspondence department, be sure and enclose stamp.

Books Received 3

Alternating Current Machinery. William Esty,

412 pp., 9 1/2 X 6 1/2. Half seal leather. Price; $3.50.

American School of Correspondence, Chicago, 111.

Supplied by Amateur Work.

This book has been prepared with the special object of giving the beginner, as well as the practical electrician, a working knowledge of alternating current apparatus, so that he may know how to install and operate it intelligently. It seems to be a very common opinion that to acquire such knowledge requires an extensive mathematical training, but that such an idea is erroneous, is evident from a perusal of this book, which is clearly and interestingly written and very completely covers the field for which it is intended. It contains no mathematics beyond the simplest trigonometry, and but little of that.

It assumes that the reader has some acquaintance with the simpler laws of electricity and magnetism, the opening chapters presenting the essential features of the source of alternating currents and the alternator, and progressively takes up and explains the various phases of this interesting and important department of electrical work.

Maxwell's Theory and Wireless Telegraphy. Part I. Maxwell's Theory and Hertzian Oscillations, N. Poincare; translated by Frederick K. Vreeland. Part II. The Principles of Wireless Telegraphy. Frederick K. Vreeland. 250 pp., 8 1/4 X 5 3/4; Cloth. Price $2.00. McGraw Publishing Co., New York. Supplied by Amateur Work.

The object of this book is to give a physical treatment of theory and its application to some modern electrical problems, to set forth the fundamental principles which underlie all electrical phenomena, according to Maxwell and his school, to show how these principles explain the ordinary facts of electricity and optics, and to derive from them a practical understanding of the essentials of wireless telegraphy.

Mathematics and abstruse reasoning are avoided, making a book which the busy man or student may peruse with interest and profit. While it does not describe all the numerous forms of apparatus now in use, it does present those features necessary to a practical knowledge of the subject, and in such a clear and interesting way as to make the book of the utmost value to those desirous of studying the underlying principles of this important field of electrical research.

Practical Electricity. W. E. Ayrton. 642 pp. 7 X 5 in. Cloth. Price $2.00. Cassell & Co., Ltd. London and New York. Supplied by Amateur Work. It is not necessary to mention this book to any electrical engineer; itis a constant reference book toall, and is so complete and contains so much of valueto every day work that it cannot be too highly recommended. No student of electricity can invest in a book which will be of more practical value than this; we cannot speak too highly of it. Its special field is that of experimental and testing work with instruments, which is treated with great fullness. It is just the book for amateurs who have progressed beyond first principles.

Manual of Mechanical Drawing. Philip D. Johnston, 150 pp., including 69 plates, 9 1/2 X 7 1/2. Cloth. Price $2.00. David Williams Co., New York. Supplied by Amateur Work.

This book meets to the fullest extent what, in our judgment, should be included in a text book upon this subject, and should be cordially welcomed by instructors. The exercises are in accord with modern drawing-room practice, the part devoted to geometry and projection is complete without being tiresome, and the studies in machines include a vertical steam engine with detail of parts. A student who would faithfully pursue this course of instruction would be able to do work which would meet the approval of a pretty exacting head of the drafting room.