CONTENTS

Introduction
Page
Introduction. The principle of an electric bell.[ix]
Chapter I
The Leclanche cell—Polarization—Setting tip—The dry cell—The gravity cell—Connecting up cells[1]
Chapter II
The single stroke bell—The shunt bell—The differential bell—The continuous ring bell—The waterproof bell—Forms of gongs—The buzzer—Long distance bells—The relay—The push—Three point or double contact push—Floor push—Door pull—Indicating push[9]
Chapter III
Bell wires—Joints—Running wires—How to put up a door bell—Combinations of bells, pushes and batteries—Faults in bells, faults in wiring—How to locate and remedy faults[23]
Chapter IV
Fire alarms—Thermostats—Metallic thermostats—Mercury thermostat—How to connect thermostats—Water level indicators—Burglar alarms—Open and closed circuit alarms—Window, door and shade springs—Alarm matting—Yale lock alarm—Door trip alarm[40]
Chapter V
The annunciator drop—The needle or arrow drop—The pendulum drop—Wiring up annunciators—Return or fire call systems—Double wire system—Western Electric single wire system[55]
Chapter VI
Three-wire return call system—Installing elevator annunciators—Burglar alarm annunciators—Clock alarm circuit—Bells for high voltages—Bell-ringing transformers—Combination bell, door opener and telephone circuits—Fire alarm circuit—Interior fire alarm system—Fire alarm system for considerable areas[64]