ANSWER
To catch counterfeiters
In 1696, after a long career in academia, Sir Isaac Newton was appointed Warden of the Mint. He took up residence in the Tower of London, then home to the mint, and set about solving the two problems that plagued British currency at the time: clipping and counterfeiting. Clipping, the practice of clipping or filing small bits of metal from the edges of coins, was slowed considerably when Newton introduced new coinage to the realm. The new coins had reed (or milled) edges - little ridges around the edge of the coin, the lack of which made it readily apparent that a coin had been tampered with and was not worth its full weight.
Dealing with the problem of counterfeiting was an endeavor Newton particularly enjoyed. He would disguise himself and hang around in bars, brothels, or anywhere he might expect to encounter common criminals, and eavesdrop on their conversations and generally snoop around. He caught a fair number of counterfeiters this way, and sent many of them to their deaths on the gallows.
In 1699 Newton was appointed Master of the Mint, a position he held until his death in 1727.
WHO GOT IT RIGHT: JP Weigt, Pete Daggett, Bob Milligan, Marika Thiessen, Stephanie Poarch, Iron Saul, and Marc Quinlivan.
