Sean,
A question.  You mention the use of ceramic or glass plates for bases,
but a problem of slipping off in strong quakes.  In =93Building Scientifi=
c
Apparatus=94 by Moore, Davis and Coplan there is a discussion of kinemati=
c
design and in particular being able to replace (and replace) an item in
a stable position exactly.  The essense is to use three feet, each foot
being a ball bearing.  The plate they sit on is the trick.  One foot
rests in a three sided pyramidal depression, the second is in a V-groove
generally aimed at the pyramidal depression, and the last bearing rests
on a flat surface.  These resting points could easily be constructed out
of glass or ceramic tile pieces.  The result would be a very stable
mounting where the object mounted would be very resistant to sliding off
the pedestal except in the most violent episodes.  Do you think there
are other problems I=92m missing?
Charles R. Patton


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