Two theories on loose pieces: If it is obvious to the visitor that if they
take it away the exhibit won't work, they tend to leave it there.  It seems
to generate a high guilt factor in them, or something.  Second theory is
if it has some intrinsic value by itself it is more likely to disappear.
This is best demonstrated with things li
 
 
 
 
 
ike magnets or rubber
balls.  They will definitely disappear.  I guess your sintra discs did look
like they would be useful for tiddlelywinks or hockey.  Those things you do
need to tie down use a weighted cable or braided rope with a fishing swivel
at the object.  (The weight goes up and down inside a tube, pulling the rope
and the object back when visitors let go).  It's engineering at it's best-
very simple.  I credit the orginal idea to the Exploratorium, but is there an in
dividual it can be credited to?  Clifford Wagner
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