Enquire within upon everything

[Footnote 1: Billiards made Easy. With the scientific Principles of the Spot-stroke, and the Side-stroke, familiarly explained: By Winning Hazard. Illustrated by practical diagrams. With a chapter on Bagatelle: Houlston and Sons.] 2591. Boss; or the Fifteen Puzzle. Apparently simple, this game is really difficult of solution, Fifteen cubes of wood, severally marked from I to 15, are placed indifferently in a box made to hold sixteen; thus: --------------------------- --------------------------- | | | | | | | | | | | 9 | 11 | 3 | 7 | | 1 | 2 | 3 | 4 | | | | | | | | | | | |------+------+------+------| |------+------+------+------| | | | | | | | | | | | 8 | 14 | 10 | 15 | | 5 | 6 | 7 | 8 | | | | | | | | | | | |------+------+------+------| |------+------+------+------| | | | | | | | | | | | 6 | 12 | 13 | 2 | | 9 | 10 | 11 | 12 | | | | | | | | | | | |------+------+------+------| |------+------+------+------| | | | | | | | | | | | 5 | 1 | 4 | | | 13 | 14 | 15 | | | | | | | | | | | | --------------------------- --------------------------- The puzzle consists in sliding the cubes from square to square, without lifting them or removing them from the box, until they are placed in their natural order. It is easy enough to move the squares up to 12; but to get the last three into order is often a puzzle indeed. If the figures fall in either of the following positions--13, 15, 14; 14, 13, 15; or 15, 14, 13--the problem is unsolvable; it follows, therefore, that the last row must be either 14, 15, 13; or 15, 13, 14. If you get the cubes into either of these positions, you can easily bring them right; but if you cannot, the only way is to begin the game all over again. Several other ways are suggested. Cavendish (Mr. H. Jones) thinks he solves the puzzle by turning the box half round; but as this is only possible when the figures are on circular pieces of wood, his solution merely cuts the knot, instead of unravelling it.