Henry Ernest Dudeney/Modern Puzzles/151 - Sinking the Fishing-Boats/Historical Note

== Historical Note on by : $151$ - Sinking the Fishing-Boats == This solution appears both in 's and 's.

claims to have first given the puzzle in $1908$, but whether he copied it from of vice versa has not been determined.

Note that this puzzle is also a solution for the queen's tour on a $7 \times 7$ chessboard in $12$ moves.

, in his $1968$ repackaging, reports on:
 * 's proof that $2 n - 2$ straight line segments are necessary for a closed path on all squares
 * 's proof that, for a square array of $n$ dots on a side, as few as $2 n - 2$ straight line segments can be used to draw through them all, for $n > 2$
 * 's proof that $2 n - 2$ straight line segments are sufficient for a closed path on all such squares where $n > 3$

He also reports on the sizes of squares meeting the restriction that none of the segments go outside the borders.