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Water is a great visitor experience and a maintenance headache.   In my  
exhibit Contraptions A to Z I knew I had to include the kitchen sink in  
the exhibit so Kitchen Clutter does.  In place of water I used round  
glass beads as the media that flows beautifully, ladled out of the sink  
by ladles on belts that you hand crank, dumping into a wheel made with  
#10 food cans that, in turn, makes the Kitchen Clutter clatter.  The  
stuff looks like sugar.  It also creates rainbows if you have a point  
light source, for the exact same reason that raindrops do, though  
somewhat fainter.  It is sold by Grainger as sand blast media.  I buy  
the corser grade, still pretty small (.008 inch, I think).  I have it  
enclosed in my piece; it probably a good idea not to let visitors  
handle it, though it does not seem to make dust.  It's major hazard is  
that on a smooth floor a spill of it can be as slippery to walk on as  
ice, as all those beads act as roller bearings under your feet.   If  
you look carefully it also does some nice static electricity tricks.   
The ladles pass within an inch of the plexiglas sides of the piece and  
you can see quite a few of the beads jumping ship to marry their charge  
to the plexiglas.

  What you can do with it is create a riverbed that it would flow  
through, provided the riverbed was slanted at the angle of repose of  
the glass bead.  (The angle of repose is the angle of the sides of the  
"volcano" you would get if you pour the material from one spout onto  
one spot.   Since the beads are round it has a very low angle of  
repose.  Salt, tending to be squares, has a high angle of repose).   A  
conveyor belt or buckets could be used to return it to the top of the  
river.

There's an interactive in there, somewhere!   Let me know if anyone  
uses it for anything.

Somewhere about 20 years ago we had at the Franklin Institute a  
traveling exhibit picture show that was all about the angle of repose.   
  Anyone else remember it?  One of the things most dear to us working in  
science centers is that whatever exhibit topic we are covering we get  
to learn about that topic.   Here's a toast to fostering that joy of  
learning among our visitors.

Best,
Clifford Wagner
www.scienceinteractives.com

On May 2, 2006, at 3:42 PM, Jane Bard wrote:

> ISEN-ASTC-L is a service of the Association of Science-Technology  
> Centers
> Incorporated, a worldwide network of science museums and related  
> institutions.
> *********************************************************************** 
> ******
>
> Our museum is developing an exhibit related to our neighboring river  
> and we
> are looking for ways to represent the river in a hands-on way without  
> using
> water.  Has anyone ever seen an exhibit that uses another material to
> effectively take the place of water in showing a flow pattern?
> Thanks!
> Jane
> ________________________________________
> Jane Bard
> Director of Education
> The Children's Museum of Portsmouth
> 280 Marcy Street
> Portsmouth, NH  03801
> 603-436-3853
> 603-436-7706 fax
>
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