American Telegraphy and Encyclopedia of the Telegraph: Systems, Apparatus, Operation: Embracing Electrical Testing; Primary and Storage Batteries; Dynamo Machines; Morse, Duplex, Quadruplex, Multiplex, Submarine, Automatic, and Wireless Telegraphy; Burglar-alarm, Fire-alarm, and Police-alarm Telegraphy; Printing Telegraphy; Military and Naval Signaling; Railway Block Systems; Telegraph Wire, Cables, and Conduits; Etc
William Maver (jr.)
Free