This volume contains a collection of circuit diagrams, representing more or less completely all branches of electrical engineering, with the exception Of tele phony and telegraphy. The diagrams have been taken from actual practice. Although some are not new, it has been thought best to include them, either because they illustrate impor tant principles, or because the apparatus shown is still in extensive use. A book of diagrams limited strictly to the latest apparatus would be Of little use to the Oper ator or to the repair man. The diagrams Show much more than simple wiring connections. By their use it is possible to lay out a modern switchboard, to connect the apparatus and to understand the principles of Operation of the various electrical machines. The reader will obtain information from them in proportion to his training and experience. Armature winding is omitted, as its proper treatment would require more Space than is here available. The circuit connections are so drawn as to be self-explanatory, thus reducing the necessary text to a minimum.