Electrical Wiring And Construction Tables. Menry C. Horstman and Victor H. Tousley, 118 pp. 6x4 in. Full Flexible Morocco, \$1.50. Frederick J. Drake & Co., Chicago, I11. This book, which is a companion volume to "Modern Wiring Diagrams," is a pocket hand-book that would be of especial value to inside wiremen and to them presents material that should be of considerable benefit. It is a very good interpretation of that bewildering "Natural Electrical Code." For direct current work and data on wire and wiring material it seems to be complete enough for those who should use it. With regard to the alternating current part, the book seems to be unfortunately lacking in some things. The selection of voltages for the motor charts does not correspond to the present practice. Very little work is being done with 440 volts. This has been raised to 550 or 600 volts. The 1000-volt chart should have been worked out for 1150 volts, but even this is being superceded by the almost universal use of 2300 volts for high tension transmission in cities. No table is given for this latter voltage. The size of wire can be approximated, however, for these voltages from the data given, but this book does not tell how.

A little data on pole line work is given but not enough to be of any great value. Nothing is said about the dimensions of poles, cross-arms, fins, insulators, etc.

The alternating current formulae are of no great value to the user of the book as some of the factors in them would require a considerable knowledge in mathematics to determine and no tables are given from which these could be obtained. These factors are "P. F. for power factor of load;" "I. F. for inductance factor or sine of angle of lag;" "L. for inductive drop in line." Power factor is a derived quantity which cannot be determined except under actual working conditions and it varies constantly. For all practical purposes, however, it can be approximated by those having experience. "Inductance factor" and "inductive drop" require careful computation.

In formulae given for current in conductors (alternating) the factor W is used to represent watts. No mention is made as to whether this is indicated or recorded watts. As a matter of fact indicated watts are used. These same formulae use P. F. (power factor) as one of the elements in the equation. It would be much easier for the worker to read the current, volts and indicated watts than try to find out the power factor.

A table near the last of the book gives full load currents for motors, but does not state whether for A. C. or D. C.

The book is very well indexed and except for the few things mentioned should be a great help to wire-men and wiring contractors.

ALTERNATING CURRENT MOTORS. A. S. McAllister, Ph. D., 278 pp. 9x6 in. 122 illustrations. Cloth, \$3.00. McGraw Publishing Co., New York.

Readers of the Electrical World, American Electrician (now combined with the Elec. World and Eng.) and the Sibley Journal of Engineering will be very glad to know that Mr. McAllister's articles on alternating current motors, which appeared at various times in the above publications, have now been collected and published in book form. Those not familiar with the articles cannot afford to lose the opportunity to obtain and study this book very carefully.

The increasing use of alternating current, due to the ease of transmission and raising and lowering, makes it imperative that some form of apparatus be used whereby the alternating electric power can be changed into mechanical power. The more knowledge there is to be had on this apparatus, the more intelligently and advantageously can it be used. The apparatus now most extensively used is the alternating motor. Too little is known about these outside the designing rooms of the motor manufactures.

This book is a long stride' in the direction of a clearer understanding of the alternating current motor, and in this catagory is included the alternating current commutating motor and rotary converter. It is technical and assumes that the reader is familiar with the lower branches of mathematics, electricity and magnetism, and also the graphic method of representing alternating voltages, currents, etc. The book is not so technical, however, but what the average electrical engineer can thoroughly understand and fol low clearly the theory and formulae derivations.

The volume is very well indexed and should make very valuable reference book. It should not only be in every electrical engineer's library, but should be carefully studied. All libraries having technical books should have it on their shelves for the use of those unable to pay the moderate price.