The second edition contains all the material in the original text but much of it has been rewritten and a great deal of new material added. The more important additions include sections on complex alternating waves and wave analysis, on polyphase alternating current circuits, on the construction of the characteristic curves of direct-current generators and motors, on the design of direct and alternating-current machinery, on the Blondel diagram for the synchronous motor, on the symbolic method of analysis of the induction motor, on alternating-current commutator motors, and finally a chapter on electrical measuring instruments. The chapter on direct-current machinery has been entirely rewritten and much enlarged, and to make it complete a short chapter outlining the design of a direct-current generator has been added. This chapter and the other sections dealing with design are not intended to cover the work required in a course on design but only to give the student some idea of the formulae and constants involved.