of a railway company is under
The engines are allowed to be stationary only at
points indicated, one of which is at present vacant.
required to move the engines, one at a time, from point to point, in
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?