The Ferguson Paradox

[Simpo Two]

Thought I'd try to make this - but the thought didn't last very long!

"Make four wheels, one wheel as thick as the other three. Cut teeth in all the wheels. Put the thin wheels in one axis. Set the thick wheel to them so that its teeth may take into those of the three thin ones. Turn the thick wheel. One of the thin wheels turns one way, one the other and the third no way at all."

Answer at www.horo-logical.co.uk/ferguson.html