The Pendulum is a torture instrument that was introduced in the 13th-14th century.
The victim was first secured to a wooden bench with ropes so that it was impossible for him to move. Above the victim was a crescent-shaped blade which would begin swinging to and from. Gradually the bar to which the blade was attached would be lowered bringing it closer and closer to the victim's abdomen. It would usually be at this point that the victim would confess. If no confession was made, the blade would continue to lower until it began cutting through the victim's torso. Eventually, the victim would be cleaved in two.