PREFACE
Among all the applications of electricity to domestic or commercial uses, few are as widespread as the electric bell. Practically every building used for a dwelling, storage or manufacture requires an electric bell, annunciator or alarm system.
This book was written to explain in practical language how an electric bell system operates and how it is installed; its success shown by its large sale has resulted in this new edition which brings the subject up to date.
Many new diagrams of annunciator and burglar alarm systems have been added, together with descriptions and illustrations of wiring elevators for electric bells, wiring for door openers, the use of transformers for furnishing suitable ringing current from electric light circuits; and high voltage bells intended to be used on other than the customary low voltage battery circuits.
The author expresses his acknowledgment to the Western Electric Company for diagrams of door opener circuits in connection with their interphone systems, to Edwards and Company of New York for diagrams of fire alarms, burglar alarms and annunciators, and to the Westinghouse Company for illustrations of bell-ringing transformers.