on sliding-block puzzlesfor an excellent survey.

Dudeney ca.1917
I don't have it or a photo.
Move the pieces along the lines from spot to spot starting with the arrangement shown,so FLANDERS can be read clockwise beginning with the F at 12 o'clock.

The Fifteen puzzle was first marketed in Boston by Matthias J.

(Actually, though, some modern

I found a copy but I am missing the "14" piece.

A very slick design - the problem initial position card is visible when you look straight down through the "water."A set of passengers need to be rescued by a set of lifeboats, which can move forward, backwards, or sideways unless blocked.

Since this position has odd parity, it cannot be solved.

To solve this puzzle, I've employed a strategy common in mathematics andoperations research - when faced with a problem, try to find an isomorphismwith another type of problem for which a solution can be more easily found.

I'll include them in section F.)The Cleverwood website has from a precursor work by Hordern.

The instructions say 24 moves; Hordern says 20 moves.

The patent was denied, perhaps because the 15 Puzzle was too similar to -Kinsey 1878,which specified the tongue-and-groovearrangement now commonly used for holding the tiles in the tray.

Image is of a Russian version called Logi Toli.

Most often their "solution" entailed some way of re-defining the goal state - for instanceplacing the empty space elsewhere than at the lower right,ordering the numbers in some way other than left to right in rows down the tray, or making use of a rotation of the tray itself(thusly leaving the figures not right-side up, or employing round tiles so as to be able to re-right them afterwards).

This is the "three-letter" version of B35.

Sam Loyd really shouldn't even be credited with popularizing the impossible challenge called "14-15"in which the starting position hasonly the 14 and 15 tiles swapped.

You can try some, including many designed by Minoru Abe andSerhiy Grabarchuk.

Exchange B and I in the fewest moves.

The Eleventh Hour contained a version of a classic puzzle challenge known by various names includingthe "Crazy Knights" and "Knights Exchange."Arabesk (defunct) offered this version of Crazy Knights.

I focus on those puzzles in my collection, and show a few others for reference.

Patent - Spayd 1890I can't find this in Hordern.

Tom has modified the appearance of the pieces to resemble the 2012 IPP Design Competiton Entry
Arrow Blocks by Goh Pit Khiam, but this works differently.

Rice, who called it "The Gem Puzzle."It was a tray containing fifteen numbered wooden blocks.

This will require some lateral thinking!

In the book, they reveal that although claimedand often got inappropriate credit for its invention,the actual inventor was Noyes Chapman, a postmaster in Canastota, New York,who applied for a patent in 1880.