Vanishing puzzle
From Wikipedia, the free encyclopedia
A vanishing puzzle is a mechanical optical illusion comprising multiple pieces which can be rearranged to show different versions of a picture depicting several objects, the number of which depending on the arrangement of the pieces.[1][2]
Wemple & Company marketed an advertising card named The Magic Egg Puzzle, (How Many Eggs?) in New York in 1880.[3] Cutting the rectangular card into four oblongs allowed the pieces to be rearranged to show either 8, 9 or 10 eggs. Many other similar puzzles have been published since.[4]
Chess player and recreational mathematician Sam Loyd patented rotary vanishing puzzles in 1896 and published versions named Get Off the Earth, Teddy and the Lion and The Disappearing Bicyclist (pictured). Each had a circular card connected to a cardboard backdrop with a pin, letting it freely rotate.[5][6][7] In The Disappearing Bicyclist, when the disc is rotated such that the arrow points to A, 13 boys can be counted, but when it points to B, there are only 12 boys.[8]
Prizes from $5 to $100 were offered for the best explanation of one illusion. Though the names of the winners were published, their explanations were not.[9]
