The online museum of unworkable devices is dedicated to showcasing, categorizing, and discussing the physics and engineering of many perpetual motion machines. As the welcome notice says, "This museum is a celebration of fascinating devices that don't work. It houses diverse examples of the perverse genius of inventors who refused to let their thinking be intimidated by the laws of nature, remaining optimistic in the face of repeated failures." You can find detailed discussions of overbalanced weight machines here. There are also exciting designs of fake perpetual motion machines (like the drinking bird) that you can build yourself.

For more surprising machines that look like they shouldn't be possible check out the double pendulum, sometimes referred to as the chaos machine to get the feel for "quasi-perpetual."

And remember: beware of hoaxes – they all have a hidden engine somewhere!

The photograph of Robert Boyle comes from Wellcome Images, a website operated by Wellcome Trust, a global charitable foundation based in the United Kingdom.