This book sets down, in nearly 1,000 pages, the greater part of the war-time course given to U.S. officers at the Cruft Laboratory, Harvard University. The range of material included is necessarily very great and, as Prof. Chaffee has frankly stated in his foreword, "... the scope and the method of presentation of the material in this volume are not on a graduate level. . . ." Indeed, this could not possibly be so in a single volume which includes : A.c. vector theory ; bridge and other measurements ; transient analysis ; network theory ; wave-filters ; thermionic emission ; electron dynamics ; transmitter and receiver circuits ; gas-discharge tubes ; modulation theory ; timing, rectification and control circuits. The treatment is essentially technological and, in many places, merely descriptive. Electronic Circuits and Tubes By the Electronics Training Staff of the Cruft Laboratory, Harvard University. Pp. xxiv + 948. (New York and London : McGraw-Hill Book Co., Inc., 1947.) 45s.