The alarm unit consists of a spring-powered rattle wheel and an anchor like the one for a recoil movement. Attached to the anchor is a hammer. When the rattle wheel activates the anchor, the hammer goes ding ding against a bell. Alongside the hammer is a lifting lever. When the lifting lever is raised, it jams the anchor against the rattle wheel and prevents it from turning. When it's lowered, the rattle wheel is released and noise happens. A wire runs from the lifting lever up to the center of the clock, where it attaches to a cam lever. The other part of the alarm is the alarm disk, which fits over the hour pipe and turns with the hour hand. On the front it has numerals like a clock dial. On the back is a cam with a notch in it, parallel to the XII marking on the front of the disk. The cam lever rides on the cam, and holds the anchor up against the rattle wheel. When the XII arrives straight up, the cam lever falls into the notch and releases the rattle wheel. SETTING To set the alarm, turn the alarm disk so the desired time (on the disk) is directly beneath the hour hand. For example, to have the clock go off at 9:00, turn the disk so the IX is below the hour hand. Then when the hour hand points to 9, the XII will be straight up and the alarm will go off. There is no shutoff for the alarm. When released, it will sound until its spring runs down. Therefore, a prudent person will wind it only one or two turns. ------------------ See also THIS THREAD.