Harry Houdini's trick: Metamorphosis
Harry Houdini would be tied into a large bag which was placed in a trunk. Mrs. Houdini would pull a curtain in front of the cabinet and then clap three times. At the third clap, Houdini would appear from behind the certain.
The secret behind this, Houdini would escape from the bag very fast. He would exit through a trapdoor in the trunk. Then, Mrs. Houdini would enter through the door, and tie herself in the bag. People wouldn't understand how this happened.