Dave,

Is there any force keeping the free mass centered?  Air flow changes? 
If so then you are back to having a natural period.

I'm not a fluids guy, but I wonder if small scale turbulence in air flow 
would cause an unpredictable wandering and the fall to the floor you 
mention.  Is there an active way to keep the thing centered, maybe 
radiation pressure from lasers?  Any active correction could be measured 
and removed from data.

Scott

David H. Youden wrote:
> All,
> 
> I have been thinking ( a dangerous thing, to be sure) about a 
> seismometer that has no natural frequency. Perhaps (probably) this idea 
> is not new, but never-the-less, here it is:
> 
> Imagine, if you will, a stack of, say 1" diameter aluminum tubes . . .
-- 
A day without math is like a day without sunshine.

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