A communigraph is a device which consists of a pendulum suspended over a small table. The table contains small metal plates, each representing a different letter of the alphabet. As the pendulum swings, its brushes against these metal plates. By doing so, it closes an electrical circuit. The chosen letter is then illuminated on the table.

This device is also known as the Ashkir-Jobson Communigraph, after its creators.

This interesting form of divination requires no special skills or training. No medium or psychic is required. Form a circle around the table, and concentrate on the question to be answered. The pendulum will begin to swing on its own. By tracing the letters that are chosen, the diviner receives clues to the ultimate answer.

Foucault’s Pendulum, courtesy Wikipedia.