compound bow

Compound bow is an archery weapon using cables and pulleys (called cams) to bend the limbs, allowing heavy draw weight with reduced force. The innovation seems obvious until you learn it came from pure accident: in 1966, Missouri deer hunter Holless Allen was reading his son's physics textbook about kinetic energy and realized you could apply mechanical leverage to bow limbs using pulleys. He patented the design in 1969, but the breakthrough commercial model came with the Jennings Model T (1974).

The compound bow revolutionized hunting and archery sports by making power accessible to people without elite strength. A lighter person could now handle the same draw weight as a heavier competitor through mechanical advantage. The History of Archery has more.