The diagram below shows how to attach an electric bell to a clock, the bell to ring at any given time. A is an alarm device cemented to the face of the clock. The flexible wire at B is connected to the battery at C, and thence to the bell D and make and break switch E. The terminal connected to the pivot of the switch may be connected to a terminal F fastened on the clock case. Thus a com plete circuit is formed with the whole of the apparatus in series.

Electric Alarm Device for a Clock.