(Sometimes also known as Dr. Lynn's Mystery, after the developer)
A half a person, from the waist upwards, is displayed. She or he is supported on a shelf, which the performer demonstrates to be not sitting on anything, and which he moves this way and that, and then removes, leaving the person apparently floating in midair. He or she can then be moved from side to side or forwards and backwards: all the time while talking or otherwise proving that they are alive!
The person is displayed facing the audience, of course, but his or her body is actually upon a board, which is supported by invisible wires at the rear of the stage. The head and upper torso are upright: but since almost no assistants can bend their body at right angles backwards at the hip, the lower part of the torso is actually a model. The body and legs behind the model are covered with dead-black, non-reflecting cloth. The shelf, the model and the shoulders of the assistant are tricked out in bright colours and are very brightly illuminated by lights which are aimed at the spectators. The shelf is supported by brightly-coloured cords — which are obviously not strong enough to suspend the assistant but which are strong enough so that s/he can hold her/himself upright; it also supports a short chain and a dagger, which reflect the light. The stage to the side of the assistant is also composed of dead-black cloth.
The whole trick here is that the black cloth absorbs so much light — which in any case is directed to dazzle the spectators to some extent — that it simply isn't seen when compared to the brightly-dressed shelf, model, and assistant. The assistant must be dressed fully — or at least below the bosom — since it's much easier to clothe a model convincingly than it is to imitate bare flesh! Moving the covered board will have to be done by the performer - by turning the assistant's shoulders — since moving anything else would give the trick away.
This is another side-show type performance.