A small gallery, with curtains at each side, lights, flowers, etc., and a railing at each side, houses the illusion. A person from about the navel upwards is situated upon a little stool-like thing which is mounted on an otherwise empty table. The spectators can see the space between the stool and the table, and under the table also: both appear to be empty. The half-person is obviously alive.
The first figure gives an idea of the gallery; of course, it need not be so formal and old-fashioned. But the curtains and the railings are essential to the illusion.
The "stool" (with the usual three legs) actually is just a ring of wood or other material attached to the legs, which are two or three or four inches high. Two mirrors, at an angle of 45 degrees to each other, are attached to the legs; they reflect the table top giving the illusion that there's nothing there. The table is at an angle to the spectators: mirrors are attached to the two sides of the table facing the audience. They reflect the carpeting on the floor; they also reflect the two table legs — identical in appearance to the ones on the table — that are mounted behind the railings in such a position as to be reflected and seem to be the two rear legs of the table. The assistant sits or kneels, which ever is most comfortable.
The spectators can approach fairly closely, but not so as to touch the table of the mirrors under it. This is one of the functions of the railings; and they and the curtains keep the spectators from getting to the side of the tableau and figuring it all out!