Page 228 - Turner J.C., P. Van De Griend "History and Science of Knots"

218 History and Science of Knots

Some time later, Henry Slade's psychic abilities were proved to be fraud-
ulent. It was shown that the phenomena he produced in the experiments were
achieved by trickery. Below [Fig. 91 we reproduce an illustration, by Zollner,
which shows the Overhand Knots produced by Slade's conjuring.

Fig. 9. Overhand knots on Zollner's sealed cord
There were some publications in which a mathematical explanation was
given for `conjuring' knots from apparently thin air. The first, by Oscar Si-
mony, was based on a prior discovery by Augustin Ferdinand Moebius (1790-
1868), that if one makes three or more likewise-handed twists in a flat strip,
and pastes the ends together, then on cutting along the centreline of this one-
sided surface a knot or knots may occur [80). In 1890 Friedrich Dingeldey, then