A spring-gun is a gun, often a shotgun, rigged to fire when a string or other triggering device is tripped by contact of sufficient force to "spring" the trigger so that anyone stumbling over or treading on it would discharge the gun. Setting or maintaining a spring-gun is illegal in many places. Uses Spring-guns were formerly used as booby traps against poachers and trespassers. Since 1827, spring-guns and all man-traps have been illegal in England. Spring-guns are sometimes used to trap animals. Although there have been few reported cases of use, there have been several unconfirmed cases over the 20th century. In the 18th century, spring-guns were often used to protect graveyards, offering an alarm system of sorts to protect newly buried bodies, which were often stolen by grave-robbers who supplied anatomists with cadavers. Spring-guns were often set to protect property. For this purpose, spring-guns are often placed in busy corridors such as near doors. A trespasser opening the door completely would then be shot. Residents who are aware of the trap use a different door or open the door halfway and disconnect the tripwire. To reduce fatalities by using this trap, non-lethal calibers are often used, or the spring-gun is fitted to fire less lethal ammunition. For example, in the United States, most spring-guns are loaded with non-lethal caliber or shot to avoid liability arising from the use of deadly force in the protection of a property interest. Posting clear and unmistakable warning signs as well as making entry to spring-gun guarded premises difficult for innocent persons, such as high walls, fences and natural obstacles, are significant ways to reduce potential tort liability arising from the spring gun's wounding of a careless or criminal intruder. Important US lawsuits regarding trespassers wounded by spring-guns include Katko v. Briney. Bird v. Holbrook is an 1825 English case also of great relevance, where a spring-gun set to protect a tulip garden injured a trespasser who was recovering a stray bird. The man who set the spring-gun was liable for the damage caused. Documented examples An historic use of a spring-gun occurred during the night of June 3 or early morning of June 4, 1775, when a spring-gun set by the British to protect the military stores in the Magazine in Williamsburg, Virginia, wounded two young men who had broken in. The subsequent outrage by the local population proved to be the final