Another thread mentions street magician David Blaine. He is a very talented fellow. I notice that he and a few other magicians now do on-the-street levitation. My conjecture about how it works is that someone has perfected a device that extends a thin rod from the magicians trouser leg and he momentarily appears to rise when this happens. (In Blaine's TV show he walked away a distance from his onlookers and turned his back to them. ) I don't know whether the device could operate on muscle power alone (the magicians always seem to raise their arms when they levitate) or whether it might be spring powered or air powered.
