Where can I find this scientific toy?
January 13, 2004 6:09 PM   Subscribe

I need help finding a scientific-type toy. [more inside]

A few years back, a friend of mine had a really neat toy. It consisted of an hourglass inside a vertical liquid-filled tube (I suspect the liquid was water.) At the start, the hourglass would be floating at the top of tube, with all the sand in the bottom half of the hourglass. If you turned the tube over (and the hourglass with it), though, the hourglass would stay at the bottom of the tube until about half the sand had flowed to the bottom, at which point it would suddenly float to the top.

I've been trying to find one of these for my collection of "toys for grown-up geeks", but haven't been able to do so yet. Does anyone know where to buy such a gizmo, or have any good suggestions for places that would be likely to sell such things? (I'm in Chicago, if it matters.)

As an aside, my friend and I did eventually manage to agree on the answer to the following question, which I now pose to you: Why doesn't the hourglass float up immediately?
posted by Johnny Assay to Science & Nature (4 answers total)
I didn't look too hard, but I hope this Grand-Illusions.com page about it helps you narrow your search.
posted by riffola at 6:20 PM on January 13, 2004

Johnny: The hourglass doesn't float up right away because of bouyancy.

I was going to explain it, but this page does a better job of that. And with pictures.
posted by bshort at 8:32 PM on January 13, 2004

I guess what you are looking for is a Newton Gravity Glass . The explanation for what's happening gives even most scientists a headache.
posted by swordfishtrombones at 2:31 AM on January 14, 2004

There are some cheap versions of those floating around. I've seen them in a display at Walgreen's Drug along with Galileo thermometers.
posted by mmoncur at 5:18 AM on January 14, 2004

« Older Re-Download from iTunes   |   Is a random Windows update safe to install? Newer »
This thread is closed to new comments.