This is one of my very favorite coins of all time, the lovely silver "Mercury" dime. But it isn't really Mercury at all! An Act of Congress from 1837 specifies that an image of Liberty appear on all US coins. Liberty is usually depicted as a woman wearing or carrying a Phrygian cap -- a soft cloth cap like the Smurfs wore -- which is emblematic of freedom. The model was probably Elsie Kachel Stevens, the wife of poet Wallace Stevens (check out the jaw on that lady!).
This depiction is unique, because of the wings. The combination of wings with the Phrygian cap symbolized freedom of thought. We put this on a coin as a message to Europe that we didn't wish to be drawn into the war they looked to be headed for. Sadly, we did get dragged into that war AND the one after, and this coin was in circulation the whole time.
The designer was Adolph Alexander Weinman (1870-1952), an assistant to Augustus Saint-Gaudens. In 1915, the Mint invited three prominent sculptors, Hermon MacNeil, Albin Polasek and Weinman, to submit designs for the dime, quarter and half dollar. All three were allowed to submit designs for all three, and the result, intended or not, is the Weinman got two coins, the dime and the half, MacNeil got the quarter, and Polasek got nothing.
This coin was still in circulation when I was young, though it was already becoming a treat to find one.
PERMISSIONS: The US Mint specifically allows use of the "Mercury" dime design. Policy statement here.