The pendulum part from Edgar Allen Poe's "The Pit and the Pendulum."
If you're unfamiliar:
Basically, you're tied lying down on your back so that you can't move at all. Directly above you is a giant pendulum (like the the thing that swings in an old clock) that is a few meters above you. This pendulum, however, has a super-sharp blade. The pendulum swings back and forth slowly and every few swings, it drops down about a centimeter. It takes hours upon hours for the swinging blade to finally reach your abdomen. Once it does, it slowly begins to cut through your stomach, at first like a paper cut. It keeps lowering until it cuts well into your midsection as you bleed to death. It may take hours for you to die.