A potato cannon is a pipe-based cannon that uses air pressure (pneumatic), or combustion of a flammable gas (aerosol, propane, etc.), to launch projectiles at high speeds. They are built to fire chunks of potato, as a hobby, or to fire other sorts of projectiles, for practical use. Projectiles or failing guns can be dangerous and result in life-threatening injuries, including cranial fractures, enucleation, and blindness if a person is hit. The potato cannon can trace its origin to the World War II-era Holman Projector, which was a shipboard anti-aircraft weapon.