A Gun Designed to Fit inside a Coffin and Shoot Grave Robbers

In the America of a century ago, grave robbing was a lucrative business. The deceased didn't seem to mind, but their living relatives did. So they often went to great lengths to secure the bodies, including the use of steel cages.
But the best defense is a strong offense, so the more serious graveyard keepers used guns and tripwires to shoot robbers. Among their options were coffin torpedoes:

In 1878, a number of "Coffin Torpedoes" hit the market. One design by Phil Clover of Columbus, Ohio was for an abbreviated shotgun that rested just inside the coffin lid. Once the lid was raised, the gun would fire directly into the face of the violator, discharging a number of 36-caliber lead balls.
Another inventor, Thomas N Howell, perfected two different "Grave Torpedoes." Each was more like a landmine than any firearm. Borrowing Civil War technology, Howell's device weighed 8-pounds and carried a charge of more than .75-pound of black powder ignited by a percussion cap. Buried atop the coffin with a protective plate above the torpedo, if disturbed the metal plate would help serve as a shape charge directed right at the would-be grave robber. An advertisement for the weapon declared that it would allow one to, "“sleep well sweet angel, let no fears of ghouls disturb thy rest, for above thy shrouded form lies a torpedo, ready to make minced meat of anyone who attempts to convey you to the pickling vat.”
In 1881 at least three men were killed when one such device ignited during a late night traipse through the cemeteries near Gann in Knox County, Ohio.

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