Often used in scrying. Pendulums can be made of almost anything, often though a stone of some kind on the end of some cord. If they are attuned to the owner, they will answer 'yes' or 'no' questions. Not cosmic magic 8 balls, they will correctly answer, although sometimes they return a firm 'maybe, i don't *know*'. A pendulum not properly attuned is useless; you can tell almost the moment you pick it up whether it will work for you or not. They respond differently to different people; mine circles clockwise for "yes", counterclockwise for no, and jerks up and down or back and forth for 'maybe'. I've heard of pendulums that go north-south for yes and east-west, not circling just swinging; it varies. The best way to have a "key" is to ask it questions you *know* the answers to, a set of yes and a set of no, and from this pattern you should be able to discern the correct response.