Victorian parties were often enlivened by a simple device called a harmonograph. It used basic physics, a pencil, and a piece of paper, to produce a large variety of beautiful designs. The invention of this device is generally attributed to Professor Hugh Blackburn, a teacher of mathematics at the University of Glasgow. He studied how multiple repetitive motions could overlap each other over time in evolving ways and came up with this simple, but interesting device.
Take a couple of pendulums, put weights on the end, and swing them back and forward. The two should not be in sync with each other. Instead, they should be set off at slightly different times, describing slightly different swings, at slightly different angles. To the top of one pendulum, attach a pad of paper. To the top of another, attach a simple wooden arm with a pen or pencil attached to it. Put the pen or pencil on the paper, and the slightly off-kilter swings of the pendulums will trace out a strange shape. Depending on the angles of the pendulums, the length of their path, and the time it takes them to describe it, they'll come up with a seemingly endless variety of shapes.
This invention, called the harmonograph because it made a written record of the harmony of the pendulums, caught on like wildfire. People created more elaborate ones, replacing one or both swinging pendulums with arms that could rotate and swing out long ovals. Eventually people added a third arm, which would be attached to the pen-holding arm, and so the two would interfere with each other's swings, creating an even more complex pattern. People published guides which showed the right movement to produce certain patterns. Others just experimented. It was an entertaining party game for the rest of the century.
It also was one of the first inventions that caused people to question the nature of art. The harmonograph produced images that weren't the result of the glory of nature or the artistry of humans, both of which were acknowledged without difficulty. This was a simple mechanical device, built by humans, that could produce a seemingly endless variety of pleasing shapes and beautiful images. And remember, this was a time when humans were just beginning to break away from realistic painting and focus on shape and color.
In the end, the harmonograph was no threat to art — or at least not as much a threat as human performance artists were (zing!) — but it was one of the first signs that human artistry was in for tougher competition than had previously been thought. You can, of course, build your own harmonograph today. Set in on fire, and you might get a grant from someone.