Henry Ernest Dudeney/Modern Puzzles/222 - A Mechanical Paradox
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Modern Puzzles by Henry Ernest Dudeney: $222$
- A Mechanical Paradox
- A remarkable mechanical paradox, invented by James Ferguson about the year $1751$, ought to be known by everyone, but, unfortunately, it is not.
- It was contrived by him as a challenge to a sceptical watchmaker during a metaphysical controversy.
- "Suppose," Ferguson said, "I make one wheel as thick as three others and cut teeth in them all,
- and then put the three wheels all loose upon one axis and set the thick wheel to turn them,
- so that its teeth may take into those of the three thin ones.
- Now, if I turn the thick wheel round, how must it turn the others?"
- The watchmaker replied that it was obvious that all three must be turned the contrary way.
- Then Ferguson produced his simple machine, which anyone can make in a few hours,
- showing that, turning the thick wheel which way you would,
- one of the thin wheels revolved in the same way, the second the contrary way, and the third remained stationary.
- Although the watchmaker took the machine away for careful examination, he failed to detect the cause of the strange paradox.
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Sources
- 1926: Henry Ernest Dudeney: Modern Puzzles ... (previous) ... (next): Unclassified Problems: $222$. -- A Mechanical Paradox
- 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Geometrical Problems: Circle Puzzles: $296$. A Mechanical Paradox