The references, given at the end of nearly every chapter, are to the books or papers I have consulted when writing the chapter. In many cases they contain more detailed discussions of the same or similar problems, and will be helpful to the student. The proofs of several of the problems could have been considerably shortened by deducing them from the general equations of electro magnetism, but, in my opinion, the proofs given bring out the physical meaning more clearly to the electrical student.