Optical illusion magic trick consists of bolt with head and shank terminating in a nut with a dummy shank extension

摘要

An entertaining optical illusion is created by a magic trick (1) consisting of a bolt (2) with a head (3) and a shaft (4). The treaded (4) bolt (2) is detachable from a nut (5). The nut is permanently attached to a threaded shank (7) which appears to be an extension of the bolt (2) which also has an open (10)--sided washer (9) that is able to slide over the thread (4) but not past the bolt head (3).