The disk should be placed on a flat surface and spun. When you stare at the centre for 15 seconds and then look away, whatever you look at begins to swirl in a most disconcerting way. The disk was invented by magician and optical illusion expert Jerry Andrus and produced by Binary Arts Corporation, Alexandria, VA 22314, USA. Copyright 1998 Binary Arts Corp.

This is an amazing illusion in which, as you walk around a room looking at the dragon, it turns its head so that it appears to be following you. The design was downloaded from the web and constructed by John Davenport circa 2008. The design was originally produced for Gathering for Gardner 3 in Atlanta, Georgia, USA 16-18 January 1998. Copyright 1998 Binary Arts Corporation. It was inspired by the work of Jerry Andrus.