the slinky

 Richard James was a marine engineer employed at the Cramp Shipyard outside Philadelphia, Pennsylvania, during World War II. One day in 1943, as James was devising a spring that would hold shipboard marine torsion meters steady, one of the springs fell off his desk, springing end over end across the floor. Impressed and intrigued by the simplicity of it, James went home and told his wife he had a great idea for a new toy.

The slinky has found many other applications. During the Vietnam War, U.S. soldiers used Slinkys as mobile radio antennas. Over 250 million Slinkys have been sold.