The Sam Loyd Get Off The Earth Puzzle
This puzzle was invented by the American Sam Loyd in 1898. It was printed on two pieces of card and sold more than 10 million copies. If you watch our model working for you, you'll find when the discs are set one way there are 13 characters, but when they move, one of the people disappears!
Our own Professor Fiendish has his own version: Professor Fiendish's Football Team Illusion.
We've also got two other Sam Loyd classics: The Sam Loyd Sliding Block Puzzle The Sam Loyd Eight Queens Puzzle
Links:
Tricks and Games
The Murderous Maths Home Page