Metamorphosis trick
If you do not want to know how Houdini performed his Metamorphosis trick, stop reading here.
The Metamorphosis trick uses a device known as the substitution trunk, which has a secret panel that allows its occupant to sneak out.
Having extricated himself from the sack in which he was tied, Houdini would climb out of the hidden door and crouch behind a curtain lifted by his assistant.
The magician and his assistant would then change places, Houdini appearing behind the curtain as the assistant disappeared into the box.
The assistant would then emerge from the box and sack wearing a different costume.
