Henry Ernest Dudeney/Puzzles and Curious Problems/259 - Flies on Window Panes

by : $259$

 * Flies on Window Panes
 * The diagram represents a window with $81$ panes.
 * The dots represent nine flies, on as many panes,
 * and no fly is in line with another one horizontally, vertically, or diagonally.


 * Dudeney-Puzzles-and-Curious-Problems-259.png


 * Six of those flies are very torpid and do not move,
 * but each of the remaining three goes to an adjoining pane.


 * And yet, after this change of station, no fly is in line with another.


 * Which are the three lively flies, and to which three panes (at present unoccupied), do they pass?