How does the man free himself in "The Pit and the Pendulum"?

This is one of the best and most innovative parts of Edgar
Allan Poe's short story, "The Pit and the Pendulum." When the narrator awakes once
again, he finds himself tied down; above him he sees something swinging back and forth.
He finally realizes it is a giant blade, slowly inching down toward him. Just before the
blade reaches his chest, the man realizes that if he frees his hands, he can escape. He
takes some of the remaining meat and rubs it on the bandages which bind his hands. He
knows that the rats will be attracted to it. Sure enough, hundreds of rats swarm to the
bandages; they bite through it, the man frees his hands, and he evades the deadly
pendulum.