Where does the expression "red herring" come from?

This expression, meaning a false clue, first popped up in British foxhunting circles. Smoked and salted herrings turn bright red in the curing process and emit a pungent, fishy smell. Although the term “red herring” had been around since 1420 to describe the smoked version of the fish, it was first used to mean a distraction in a British gentlemen’s magazine published in 1686. The article touted an effective way to prolong a fox hunt: Drag a dead cat across the trail, masking the fox’s scent and confusing the hounds. The author suggested using a red herring if no cats were available. Nearly 200 years later, in 1884, the term was used more precisely to mean a false clue.