This is a subject in which there have been many different interpretations. Yet throughout its history, this has been good, as the results in a practical way show. From the purely mathematical point of view, the combined achievements of its history form a single, powerful tool for predicting pointer readings in intricate electrophysical and electrotechnlcal experiments. The analysis of practical problems based on fundamental theory has given great results from the physical angle.
The book at hand is ,the first of a series of three designed to follow the subject matter presented at the Cruft Memorial Laboratory at Harvard University. It therefore is an introduction, designed to provide the physical and mathematical background prerequisite to the systematic study of such fields as antennas and wave propagation, transmission circuits including wave guides, and transit-time electronics with application to microwave generators which are the subjects of later volumes. A working knowledge of calculus and of complex algebra, and some familiarity with elementary differential equations, are presupposed. Some knowledge of alternating currents is desirable.
The work opens with the vector-analytical description of the electrical properties of matter. Along with the definition of the four essential density functions in general form, the fundamental postulate of conservation of electric charge is expressed mathematically in the equation of continuity. Under the heading of Mathematical Description of Space and Simple Media, the density functions defined for separate bodies and regions are interrelated, and the repulsionattraction postulate is formulated. Succeeding topics are Transformations of Field and Force Equations, and Electromagnetic Waves in Unbounded Regions. An introduction is then given to the study of skin-effect and internal impedance, a study of boundary line problems and the solution of the homogeneous wave equation in cylindrical coordinates using Bessel function. The last part of the text proper is devoted to electric currents where the problem is formulated in general terms for configurations involving only conductors of small circular cross-section and condensers which have a dielectric that is so thin that edge effects are negligible. Also consideration is given to closed and quasi-closed circuits that are restricted in size so that all points are in the near zone with respect to each other.
The presentation is from a purely logical approach. In the back of the book there is a short outline of historical development of the science and appendixes of helpful information. The treatment is rigorous but plain. It is valuable to those in need of it.
R. H. OPPERMANN.