machine, and then transferring this into a discussion on slnusoidal currents and voltages. This section includes the mathematical representation of vectors which is quite well illustrated for the solution of alternating current circuits. The properties of circuits involving resistance, inductance, and capacitance in parallel and in series and the solution of problems using the terms of admittance, conductance and suseeptance are thoroughly covered. The final chapter in Part Three is devoted to polyphase circuits. The next part of the book on alternating current machinery starts with a description of the transformer, its physical make-up, vector representations and equivalent circuits. The same method is used with regard to polyphase induction.motors, generators, synchronous motors, and synchronous convertors. Single phase motors are taken up separately in similar fashion and the basic types are treated. The rest of this section is devoted to transmission, distribution, switching, protective devices, and motor applications. The last or Part Five of the book, gives a concise but comprehensive treatment of fundamentals and characteristics of electron tubes, the functions and basic circuits of electron tubes and the principles of applications of electronic devices to industry. This is a plain treatment with many exercises, which if studied diligently and the problems solved, will give a thorough knowledge of electric power machinery.
R. H. OPPER~ANN.