THE EIGHT ENGINES.
(
Moving Counter Problem)
The diagram represents the engine-yard of a railway company under
eccentric management. The engines are allowed to be stationary only at
the nine points indicated, one of which is at present vacant. It is
required to move the engines, one at a time, from point to point, in
seventeen moves, so that their numbers shall be in numerical order round
the circle, with the central point left vacant. But one of the engines
has had its fire drawn, and therefore cannot move. How is the thing to
be done? And which engine remains stationary throughout?
Answer:
The solution to the Eight Engines Puzzle is as follows: The engine that
has had its fire drawn and therefore cannot move is No. 5. Move the
other engines in the following order: 7, 6, 3, 7, 6, 1, 2, 4, 1, 3, 8,
1, 3, 2, 4, 3, 2, seventeen moves in all, leaving the eight engines in
the required order.
There are two other slightly different solutions.
