Here is a puzzle that was once on sale in the
London shops. It
a military train—an engine and eight cars.
The puzzle is to
cars, so that they shall be in the order 8, 7, 6, 5, 4, 3, 2, 1,
of 1, 2, 3, 4, 5, 6, 7, 8, with the engine left, as at first, on the
Do this in the fewest possible moves.
Every time the engine or a
car is moved from the main to the side track, or vice versa,
a move for each car or engine passed over one of the points.
the main track are not counted.
With 8 at the extremity, as shown,
is just room to pass 7 on to the side track, run 8 up to 6, and bring
down 7 again; or you can put as many as five cars, or four and the
engine, on the siding at the same time.
The cars move without the aid
The purchaser is invited to "try to do it in 20 moves."
many do you require?