The 15-Puzzle (also called the Gem Puzzle and 4-by-4 Puzzle) consists of fifteen pieces locked within a frame that will hold sixteen. The empty position allows the other pieces to be slid up, down, left and right. The pieces are moved around to scramble them and then the goal is to arrange them in some order (1 to 15, 15 to 1, odds then evens, etc.).
If you remove the pieces and randomly replace them then they can be arranged 1 to 15 only 50% of the time. But, when the pieces are locked within a frame 1 to 15, they can only be shuffled and they can always be reordered.
Noyes Palmer Chapman is usually credited with inventing the 15-Puzzle around 1874 when he showed an early version of it to friends. An improved version was being sold in Boston in 1879. By late 1879 another version called the Gem Puzzle was sold by Matthias Rice. There was a brief 15-Puzzle craze in the United States, Canada and Europe in 1880.
Chapman applied for a patent on his "Block Solitaire Puzzle" in early 1880, but it was rejected, probably because it was not sufficiently different from the August 1878 "Puzzle-Blocks" patent granted to Ernest U. Kinsey who made application in November 1877 (more on Kinsey below).
Since 1880 there have been many variations of the sliding puzzle including different sizes. Letters or symbols are sometimes used instead of numbers. Others use pictures; sliding puzzles with company logos were popular for a while. Magic square versions are solved when the numbers on the pieces add up to some sum horizontally, vertically and diagonally.
Samuel Loyd was an accomplished American chess player, chess-problem composer and puzzle author. He was also a deceptive self-promoter. In 1891 he claimed (and continued to claim until his death in 1911) to have invented the 15-Puzzle. (He also claimed to have invented the game Parcheesi.)
Lyod offered a prize to anyone who could solve his version of the puzzle in which the 14 and 15 pieces were transposed. It sold well until it became know that it is impossible to slide the numbers into order (1 to 15) if the 14 and 15 are switched. Loyd was aware of this and, thus, knew that no one could ever win the prize.
Loyd's fraudulent claim to have invented the 15-puzzle was accepted as fact until 2006 when Jerry Slocum and Die Sonneveld published The 15 Puzzle: How It Drove the World Crazy. They proved that Loyd had nothing to do with the invention of the 15-Puzzle and that its inventor was Noyes Palmer Chapman. They also found Ernest U. Kinsey's patent of a more generalized sliding puzzle.
On 22 November 1877 Ernest U. Kinsey applied for a patent on his "Improvement in Puzzle Blocks" and was awarded patent number 207124 on 20 August 1878.
Figure 1 shows a frame capable of holding 36 pieces (6x6). Figure 2 shows the ribs and grooves on the pieces that would allow them to be moved while locking them in the frame (as with a modern 15-Puzzle). His was an improvement on patent 5170.
Loyd explained that his invention could be used with numbers, letters or pictures:If blocks of two different colors are made use of, then the same can be moved about gradually, as aforesaid, to arrange the blocks in such positions as to produce different patterns. If letters or numbers are employed on the surface of the blocks, then the puzzle will be to move those blocks so as to arrange them to spell words or to bring the blocks in certain orders. If the surfaces of the blocks compose a picture, then the puzzle will be to arrange the blocks in the order to make up the complete picture.
Kinsey's invention is simple but clever. Unlike the single-purpose 15-Puzzle, his device allowed the frame to be opened; one set of "blocks" could be replaced with another. Thus, it could provide any number of puzzles or (educational) activities.
Left = one player; right = two players
Kinsey's Slide is played on a 15x15 board on which the 98 letters of the letter pool are randomly distributed with the remaining squares filled with blanks tiles. Only the center square is unoccupied at the start of the game.
You slide the tiles around to form words. Each time you slide a tile your score is increased by one point. When you correctly check a word, your score is reduced by the number of tiles in the primary word and all cross-words (if any).
The goal is to remove all of your tiles from the board using the fewest number of slides.
Kinsey's Slide is one of our favorite single-player games. It takes some time to complete a game and it requires concentration. With each move you should try to slide more than one letter into a more favorable position. With careful play you can achieve a negative score.
Quick Intro to Kinsey's Slide
Wynne's Box and Crossword Puzzles
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