Automatic Electric Bell

—A bell having an automatic contact breaker, so that it keeps ringing as long as the circuit is closed; a vibrating or trembling bell. Generally, it is worked by a current exciting an electro-magnet, attracting or releasing an armature which is attached to the vibrating or pivoted tongue of the bell. This is done alternately so that the tongue beats against the bell. en the current is turned on it attracts the armature; as this moves towards the poles of the magnet it breaks the circuit by drawing the “contact spring” away from the “contact point.” The movement of the armature causes the hammer on the end of the lever to strike the bell. A spring draws the armature back to its original position and the cycle repeats, thus causing a continued ringing.