"A spring, a spring, a marvelous thing! Everyone knows it's Slinky!" Though its popularity can't be called into question, "everyone" may not know that the Slinky was an accident. Created by mechanical engineer Richard James in 1943, it was the unintended by-product of a new line of sensitive springs that would help keep fragile equipment steady on ships. After knocking one of his newly created springs from a shelf, James watched as it "walked" down from its spot instead of falling to the ground. With a machine designed to coil 80 ft. of wire into a 2-in. spiral and a name chosen by his wife Betty, James began producing his novelty Slinky — but at first to little notice. Slinky got its big break during the Christmas shopping season of 1945, when the Gimbels department store in Philadelphia let James demonstrate his new creation. Within minutes, he sold 400 Slinkys. Sixty-six years and 250 million Slinkys later, we're still just as delighted with James' serendipitous toy as we ever were.