Something for nothing

Cars that run on water, and fusion machines that generate more energy than they use are staples of inventors’ fantasies. They pop up all the time. Charles Redheffer raised large sums of money in Philadelphia with a perpetual motion machine and then took it to New York in 1813, where hundreds of people paid a dollar each to see it.

It did, indeed, seem to keep itself turning. In the end, sceptics removed some wooden strips to find a cat-gut belt drive, which went through a wall to an attic where an old man was turning a crank.

But the dream continues. In 1984, CBS News in the US featured the "energy machine" of Joe Newman, who declared: "Put one in your home and you’ll never have to pay another electric bill." People the world over are still getting bills.