When one electric bell is operated from two push-buttons it is impossible to tell which of the two push-buttons is being operated unless an annunciator or similar device is used. A very simple annunciator for indicating two numbers can be made from a small box, Fig. 1, with an electric-bell magnet, A, fastened in the bottom. The armature, B, is pivoted in the center by means of a small piece of wire and has an indicator or hand, C, which moves to either right or left, depending on which half of the magnet is magnetized. If the back armature, D, of the magnet is removed the moving armature will work better, as this will prevent the magnetism from acting on both ends of the armature.
The wiring diagram, Fig. 2, shows how the connections are to be made. If the pushbutton A is closed; the bell will ring and the pointer will point at 1, while the closing of the push-button B will ring the bell and move the pointer to 2. --Contributed by H. S. Bott, Beverly, N. J.
Illustration: Annuciator and Wiring Diagram