Where does the term reaching for the brass ring come from?

Merry-go-rounds (or carousels) used to have a separate device from which hung a brass ring. As the merry-go-round turned quickly, if you could reach out way far and somehow manage to grab the brass ring, when the ride was over, you could show the brass ring to the ride operator and he would either give you a prize or let you ride again for free. It was really hard to get the brass ring. So, reaching for the brass ring means that you try really hard to do something that almost no one else can, just so you can enjoy the praise and reward that comes with it.