The vanishing bird cage, also known as the flying birdcage, is a classic parlour magic effect that was invented by French magician Buatier De Kolta.
Often there is a bird, though in modern performances of the act it is usually fake, inside the cage.
The magician will offer the cage for inspection by an audience member, but he will never actually release his grip of it.
Two of the opposite corners of the cage pull away from each other so that the box becomes somewhat of a tube, about 18 inches long and only one or two inches thick, that resembles a bundle of wire that is thicker in the middle than at the ends.
An elastic cord attached to one end of the cage runs up the sleeve of the magician's jacket so that when the cage collapses, it is drawn up his sleeve and hidden from view.