Peter Jensen Brown’s “Charles Monk, Monkey Wrenches and ‘Monkey on a Stick’ – a Gripping History and Etymology of ‘Monkey Wrench’” is one of those philological investigations I so love. Here’s the conclusion:
It is nearly certain that Charles Moncky (or Monkay) of Brooklyn did not invent, coin, or inspire the term, monkey wrench; despite the actual existence of Charles Monk, the tool-maker from Brooklyn. That story may have been fabricated as a joke, given his tool-related occupation and playing on the similarity of his last-name to the well-known wrench; or could have, I suppose, been an honest mistake made somewhere along the line. In any case, he was too young to have been responsible for either the expression or the tool.
The three general types of monkey wrench, English, Merrick and Coes, all share similarities with the children’s toy, “monkey on a stick.” Pile-drivers, well-drillers, monkey engines and monkey machines also share similar attributes. They all have a movable “monkey” that climbs up and down along shaft; like a monkey climbing a tree – or a “monkey on a stick.” The theory is at least simple, consistent across several different contexts, and plausible.
But the post is full of great images and quotes; check it out. (Have you ever heard of “monkey on a stick”? I hadn’t.) Via Mark Liberman at the Log.