Answer: The Slinky
The Slinky has been in production for over seventy years and shows no signs of vanishing from toy store shelves. It’s a classic children’s toy; it’s simple, inexpensive, and the novelty of playing with a wiggly, wobbly, walks-down-the-stairs spring hasn’t waned much over the decades. While most people have a childhood memory or two involving a Slinky and likely even went on to buy one as a gift, very few people know that the toy came to life in a military lab.
In 1943, a young naval mechanical engineer by the name of Richard James was working on designing a system of springs that could support and stabilize sensitive instruments aboard naval ships in rough seas. During the course of his research, James accidentally knocked a coiled spring off of a shelf in his lab at the William Cramp & Sons shipyards in Philadelphia. The spring went tumbling, landed on a pile of books, flipped over itself, and then proceeded to “walk” itself down the books, flop onto a table, onto the floor, and then coil itself back up into a neat stack.
James was so enamored by the antics of the spring that he went home and told his wife how he thought he could tweak the composition of the spring to consistently walk about in the fashion he had witnessed in the lab. He experimented with different steels and spring lengths over the next year, and the couple ultimately formed a small company to market the spring toy. James and Betty had a very difficult time selling the toy until November of 1945 when they were granted permission to set up a ramp in the toy section of Gimbels Department Store in Philadelphia. When children were afforded the opportunity to play with the Slinkys, they proved to be irresistible. The first run of 400 Slinky units sold out in less than two hours.
The Slinky has remained a consistent seller over the years with over 300 million units sold since its introduction in 1945.