England is old and small and they started running out of places to bury people. So they would dig up coffins and would take the bones to a “bone-house” and reuse the grave. When reopening these coffins, one out of 25 coffins were found to have scratch marks on the inside and they realized they had been burying people alive. So they thought they would tie a string on the wrist of the corpse, lead it through the coffin and up through the ground and tie it to a bell. Someone would have to sit out in the graveyard all night to listen for the bell.