This most ancient of magical presence detectors is NOT the
genuine Egyptian scrying bowl (made in China and purchased at the
dollar store!) shown in the photo above.
It is that tiny sliver of metal floating in water in the bowl
... a magnetized steel needle stuck through a piece of Styrofoam.
In other words, a magnetic compass. Curiously enough, although
the sphinxes which carry it did not originate in China, the
compass apparently did, where it was used to guide caravans
through the deserts and steppes of Asia for hundreds of years
before being "rediscovered" by Europeans. This is just
some background information to help you weave your tale of truths
and deceptions before the demonstration.
The deception comes when you discuss how some people are said
to have "magnetic personalities." Is this truth or
fiction? You claim it is true and that you should be able to
prove it by locating someone among the onlookers with just such a
magnetic personality.
As the onlookers one by one place a hand over the compass,
you decide which ones have magnetic personalities by the effect
they have on the compass. Most people will have no effect
whatsoever. Others will have such a strong magnetism about them
that the compass needle spins wildly. It's all under your
control, or rather, controls.
It can also be done using an ordinary magnetic
compass as described in the article.