A harmonograph is a pendulum based like mechanical device that creates harmonograms (complex lissajous figures).
These are essentially recordings, often traced by pen or pencil on to paper (though can also be simulated on a computer monitor though programming) of the way a complex or compound pendulum swings.
A large heavy rectangular platform is connected via metal cables at each corner to a supporting frame. The pyramids on the table are weights(1-2kg) that can be moved around the table.
This changes the way the platform slows down producing a unique pattern each time. see also how harmonographs work
A harmonograph at Questacon, Canberra, Australia. image: R.Conan-Davies
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