Kay,

My guess is that this device was simply to demonstrate wave propagation, 
and reflection at the ends (representing media boundaries). I doubt that 
the wave is torsional is important to the demonstration.

Another fact that might have been mentioned during a demonstration is 
that the motion of the end of each dowel appears up-and-down, for small 
amplitudes when viewed from the side. I have seen demonstrations using 
the same type of apparatus, where a few of the dowel ends are painted 
with bright colors so their motion can be more easily followed when 
observed from the side.

Karl


Kay Wyatt wrote:
> Dear friends,
> 
> John Lahr's wife, Jan, gave me much of John's earthscience activities 
> and experiements.  I'm familiar with most of them, but there is one in 
> particular that I could use some help on.  I have posted some pictures 
> at http://www.oregonshakes.com/temp/Lahr/ for your review.
> 
> The device appears to be a torsion wave generator but I'm not familiar 
> with torsion waves generated by earthquakes (which was John's primary 
> focus). Could this be something else related to earthquakes?
> 
> Be sure to look at the move link on the website so that you can see it 
> in action.
> http://www.oregonshakes.com/temp/Lahr/MOV04260a.MPG
> 
> If any of you have ideas, please let me know.
> 
> Thanks so much,
> Kay Wyatt

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